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The life history and distribution of lampreys in the Salmon and certain other rivers in British Columbia,… Pletcher, Ferdinand Tony 1963

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THE LIFE HISTORY AND DISTRIBUTION OF LAMPREYS IN THE SALMON AND CERTAIN OTHER RIVERS IN BRITISH COLUMBIA, CANADA.  by Ferdinand Tony P l e t c h e r B . S c , U n i v e r s i t y of B r i t i s h Columbia, 195$.  A Thesis Submitted In P a r t i a l F u l f i l m e n t Of The Requirements For The Degree Of Master of Science  i n the Department of Zoology  We accept t h i s t h e s i s as conforming t o the required standard  THE UNIVERSITY OF BRITISH COLUMBIA October, 1963  In the  presenting  r e q u i r e m e n t s f o r an  British  for reference  for  extensive  p u r p o s e s may his  be  of  and  granted  written  Department  of  by  It  this thesis  w i t h o u t my  in partial  degree at  the  Library  study.  the  f  Head o f my  i s understood  Columbia,.  /?<^3  of  the U n i v e r s i t y  of  s h a l l make i t f r e e l y  this thesis  permission.  S" e^fc-eto^ L^r  fulfilment  I further  agree for  that  copying  shall  per-  scholarly  Department  that  for f i n a n c i a l gain  The U n i v e r s i t y o f B r i t i s h V a n c o u v e r 8, Canada. Date  that  copying of  representatives.  cation  advanced  Columbia, I agree  available mission  this thesis  not  i  or or  be  by publi-  allowed  ABSTRACT The a n a l y s i s of the l i f e h i s t o r y was c a r r i e d out from c o l l e c t i o n s that were predominantly Lampetra p l a n e r i from the Salmon River and Entosphenus t r i d e n t a t u s from the N i c o l a and Thompson Rivers and from Vancouver Island streams. The taxonomy of B r i t i s h Columbian lampreys i s reviewed and c h a r a c t e r i s t i c s determined f o r separating large ammocoetes. The duration of adult l i f e , d i s t r i b u t i o n w i t h i n streams, l e n g t h , sex r a t i o , and fecundity was determined f o r both species. The spawning behaviour of both species i s described from f i e l d and l a b o r a t o r y observations. Temperature a f f e c t e d length of spawning period, spawning behaviour, sex r a t i o , and r e l a t i v e abundance of L. p l a n e r i . Hatching of lamprey eggs was dependent on temperature and d i f f e r e d between the two species. Newly hatched ammocoetes emerged from the gravel nests during darkness, were c a r r i e d downstream by the current and were deposited i n mud beds of quiet pools where they buried. The bottom preference of small ammocoetes was mud> gravel> sand and was r e f l e c t e d i n f i e l d d i s t r i b u t i o n s where greatest concentrations of ammocoetes were found i n mud bottoms. The greatest concentration of ammocoetes of mixed age classes was i n the deep pool ammocoete beds w i t h sand, l e a f , and s i l t bottoms. Ammocoetes kept i n aquaria moved t h e i r burrows f r e q u e n t l y . Ammocoete i n t e s t i n e s contained predominantly diatoms whose abundance corresponded to the season of most r a p i d ammocoete growth.. Adult and ammocoetes were not eaten by salmonid and other f i s h e s of the Salmon  River p o s s i b l y because of a p r o t e c t i v e substance i n t h e i r s k i n . Transformation  to a d u l t s f o r both species occurred i n  the f a l l a f t e r at l e a s t f i v e years of ammocoete l i f e . P r o b a b i l i t y paper was used to analyse  length-frequency  d i s t r i b u t i o n and to construct growth curves. The growth curves of both species was very s i m i l a r and nearly l i n e a r . The average length of l i f e cycle f o r L. p l a n e r i was s i x years or more and that of E. t r i d e n t a t u s was seven years or more. Adult E. t r i d e n t a t u s p a r a s i t i z e d t r o u t i n E l s i e and Cowichan Lake t o the greatest degree during the e a r l y spring and attacked salmon and other f i s h i n the sea during the summer months.  xii ACKNOWLEDGEMENT The author wishes t o express h i s g r a t i t u d e t o the f o l l o w i n g persons: - to Professor P.A. L a r k i n f o r h i s encouragement, i n s p i r a t i o n , and s u p e r v i s i o n i n a n a l y s i n g r e s u l t s and preparing the manuscript. - to Professors W.A. Clemens, P. Ford, W.S. Hoar, T.G.  Northcote, N.J. Wilimovsky f o r t h e i r c r i t i c a l reading of  the manuscript. - t o Dr. J . Briggs and Dr. C.C. Lindsey f o r t h e i r s u p e r v i s i o n , suggestions, and advice during the p r e l i m i n a r y stages of the study. - t o the I n s t i t u t e of F i s h e r i e s f o r p r o v i d i n g f i n a n c i a l assistance to c o l l e c t data and f a c i l i t i e s f o r experimentation. - to the B r i t i s h Columbia F i s h and Game Branch personnel f o r t h e i r a s s i s t a n c e i n c o l l e c t i n g data: G. Hartman, D.R. Hurn, G. Vincent, and W. Fowkes. - t o Doctors G. P i l e , D. M i l n e , and P. Wickett of the P a c i f i c B i o l o g i c a l S t a t i o n at Nanaimo f o r data and suggestions. - to Dr. W. P f e i f f e r , M.A. Hafeez, and S.N. Ahsan f o r their h i s t o l o g i c a l assistance. - t o the many f e l l o w students f o r t h e i r a s s i s t a n c e and suggestions. - t o Frances L. P l e t c h e r f o r her encouragement throughout the study and i n preparing the manuscript. - t o Dr. J.R. S t e i n f o r her a s s i s t a n c e i n i d e n t i f y i n g  diatoms.  - t o W.E. Roberts f o r h i s a s s i s t a n c e i n c o l l e c t i n g data.  iv TABLE OF' CONTENTS LIST OF FIGURES  vi  LIST OF TABLES  xi  ACKNOWLEDGEMENT  xii  INTRODUCTION  1  DESCRIPTION OF THE STUDY AREA  6  A. P h y s i c a l d e s c r i p t i o n of the Salmon River 1. Mapping and s t a t i o n s 2. Drainage 3. Flow 4. Temperature  6 6 6 11 11  B. B i o l o g i c a l d e s c r i p t i o n of the Salmon River .1. Plant cover 2. Aquatic plants 3. Animal l i f e  15 15 15 16  METHODS AND PROCEDURES  17  A. C o l l e c t i n g methods f o r ammocoetes  17  B. C o l l e c t i n g methods f o r adults  18  RESULTS AND A REVIEW OF THE LIFE HISTORY  20  A. Review of the taxonomy of B.C. lampreys 1. I d e n t i f i c a t i o n of adults 2. I d e n t i f i c a t i o n of ammocoetes 3' Nomenclature 4. Comparison of European and B.C. L. p l a n e r i  20 20 23 25 27  B. Adult L i f e 1. Duration of adult l i f e 2. Length of adults 3. P a r a s i t i c l i f e of E. t r i d e n t a t u s 4. Sex r a t i o and length of spawners 5. Fecundity of B.C. lampreys 6. Spawning of lampreys a. Method of a n a l y s i s b. Spawning requirements c. Sexual dimorphism at maturity d. Prespawning a c t i v i t y e. F i r s t sign of spawning f. Nest b u i l d i n g  23 23 31 36 41 45 51 51 54 64 72 75 76  V  g. h. i. j. k. 1. m. n. o.  Combination rock l i f t i n g - d i g g i n g Digging a c t i o n Courting behaviour Spawning act Internal f e r t i l i z a t i o n Length of spawning period Communal spawning Displacement behaviour E f f e c t of temperature  C. Ammocoete L i f e 1. Method of hatching lamprey eggs 2. Embryonic and e a r l y l a r v a l l i f e 3. Hatching r e s u l t s 4. Burrowing and swimming a c t i o n of larvae 5. C o l l e c t i n g emergent ammocoetes 6. Bottom type preference • 7. I n t e s t i n e a n a l y s i s of ammocoetes 8. P r o t e c t i v e nature of lamprey skin 9. D i s t r i b u t i o n of ammocoetes w i t h i n stream 10. R e l a t i v e abundance of ammocoetes 11. Burrowing behaviour of ammocoetes 12. Movement of ammocoetes i n burrows 13- Growth of ammocoetes 14. Entosphenus ammocoetes 15. Age determination and growth 16. Transformation of ammocoetes D. Community r e l a t i o n s h i p and m o r t a l i t y  7$ 7$ 82 84 90 91 94 9$ 101 105 105 106 106 10$ 109 109 116 120 126 135 13 S 140 141 146 14$ 161 167  DISCUSSION  170  SUMMARY OF SPAWNING BEHAVIOUR  16*3  SUMMARY OF LIFE CYCLES  184  CONCLUSIONS  186  LITERATURE CITED  190  vi LIST QF FIGURES Figure 1. 2.  '  Page  P a c i f i c lamprey drying i n the sun at Moricetown on.the Bulkley River  5  Rivers and streams i n B r i t i s h Columbia where lampreys were c o l l e c t e d and studied  7  3 • C o l l e c t i n g s t a t i o n s on the Salmon River  8  4 . Section of the Salmon River below s t a t i o n 1  10  5 . Pool area of the Salmon River  10  6.  Mean weekly discharge and maximum water temperature (Salmon R i v e r , S t a t i o n 1, 1960-61)  12  7.  Mean weekly discharge and maximum water temperature (Salmon R i v e r ; S t a t i o n 1, 1961-62)  13  8.  Mean weekly discharge and maximum water temperature (Salmon R i v e r , S t a t i o n 1, 1962-63)  14  9.  C o l l e c t i n g equipment  1$  A standard scoop of substrate with some sand removed to.show the ammocoetes at the surface  19  10.  11 . Method used to c o l l e c t ammocoetes i n the mud  19  12.  Buccal d i s c and tooth morphology of the nonp a r a s i t i c lamprey L. p l a n e r i of the Salmon River  21  13.  Schematic drawings of the buccal disc of the European and Salmon River L. p l a n e r i  21  14.  Comparison of B r i t i s h Columbian and European Ammocoetes by area of pigmentation  21  15.  Buccal d i s c and tooth morphology of the p a r a s i t i c lamprey E. t r i d e n t a t u s from the Salmon River  22  16.  Schematic drawing of the d i s c and d e n t i t i o n of E. t r i d e n t a t u s from the Salmon River  22  Myotome number i n (a) ammocoetes (b) a d u l t s  24  17.  18 . Shows how the melanophore pattern can be used to d i s t i n g u i s h ammocoetes of Entosphenus from Lampetra  26  VI1  Figure 19.  Page Length-frequency diagrams of adult (a) Lampetra p l a n e r i (b) Entosphenus t r i d e n t a t u s  33  20.  Shows the s i z e d i f f e r e n c e i n Entosphenus  34  21.  Lamprey scar on the opercule of a 6 l b . pink salmon caught near Sooke Rainbow t r o u t g i l l netted i n E l s i e Lake  37  showing lamprey scar marks  39  23.  V e n t r a l view of i n t e s t i n e of adult Entosphenus  39  24«  Length-frequency d i s t r i b u t i o n of adult L. p l a n e r i i n the Salmon River 1961-62 Experimental spawning tank Spawning tank showing current and bottom arrangement Experimental trough to t e s t response of adults to current  22.  25' 26. 27. 28.  29.  Experimental trough i n the stream, and l a b o r a t o r y tanks to t e s t the preference of spawning adults f o r l i g h t  42 53 53 5& 59  A p a i r of a c t i v e l y spawning L. p l a n e r i on the Salmon River i n b r i g h t s u n l i g h t  61  30.  Lampetra spawning i n the shade of a l o g  6l  31.  L a t e r a l view of the u r o g e n i t a l p a p i l l a of a male L. p l a n e r i and the surrounding s t r u c t u r e s Dorsal view of the second d o r s a l f i n of L. p l a n e r i comparing the s w e l l i n g present i n the female to no s w e l l i n g i n the male  67  33«  L a t e r a l view of the s w e l l i n g s present i n the female  67  34«  Displays of the upward bend of the t a i l of females and the downward bend of the t a i l of males  68  V e n t r a l view of the u r o g e n i t a l opening of E. t r i d e n t a t u s showing the p a p i l l a and the pseudoanal f i n  70  32.  35-  67  V l l l  igure 36.  L a t e r a l view of the s w e l l i n g o f the female a t the p o s i t i o n s i n d i c a t e d by t h e arrows  37.  L a t e r a l v i e w and v e n t r a l view of the u r o g e n i t a l p a p i l l a o f t h e male E. t r i d e n t a t u s  38.  Salmon R i v e r spawning a d u l t s from a communal nest  39.  Lampetra removing r o c k s from a n e s t i n an aquarium  40.  Lampetra i n an aquarium n e s t d i s p l a y i n g digging action  41.  L o n g i t u d i n a l s e c t i o n through a nest constructed by a p a i r of l a r g e Entosphenus on the Salmon River  42.  Spawning sequence of L. p l a n e r i i n an aquarium  43.  Communal spawning showing t h e p o s i t i o n t a k e n by the male i n g r a s p i n g t h e head of t h e female  44.  Communal spawning showing the p o s i t i o n of t h e t a i l of b o t h sexes  45.  Spawning Lampetra showing t h e d i s t a n c e between the u r o g e n i t a l openings d u r i n g the spawning, a c t  46.  L e n g t h of the spawning p e r i o d a t d i f f e r e n t t e m p e r a t u r e s f o r L. p l a n e r i o f the Salmon R i v e r  47.  C o i l i n g a c t i o n d u r i n g communal spawning  48.  A female c o u r t i n g a male by g l i d i n g a l o n g h i s body  49.  E x p e r i m e n t a l tank used t o t e s t t h e bottom p r e f e r e n c e of l a r g e r ammocoetes  $0.  E x p e r i m e n t a l t r o u g h t o t e s t t h e bottom p r e f e r e n c e of l a r g e r ammocoetes  51.  The p o s i t i o n t h a t t h e ammocoetes burrowed i n the bottom of a t r o u g h w i t h a c u r r e n t of 1 f o o t per second a t the s u r f a c e  52.  E p i d e r m i s of L. p l a n e r i ammocoete from t h e Salmon R i v e r , Dec. 28, 1962  IX  Figure 53. 54«  55. '56. 57.  56*.  Page Large pool where ammocoetes are deposited at s t a t i o n 1  127  Ammocoete.. beds and spawning nests at station 1  128  S t a t i o n 4, Salmon River  129  S t a t i o n 1 pool, Salmon River Length-frequency diagrams of L. p l a n e r i i n d i f f e r e n t h a b i t a t s of the Salmon River on February 23, 1962.  130 132  Length-frequency diagrams of L. p l a n e r i i n d i f f e r e n t h a b i t a t s of the Salmon River on September 9, 1962.  133  59.  Length-frequency diagrams of L. p l a n e r i i n d i f f e r e n t h a b i t a t s of the Salmon River  134  60.  Concentration of ammocoetes per standard scoop i n d i f f e r e n t bottom h a b i t a t s of the Salmon River  136  Length-frequency d i s t r i b u t i o n of ammocoetes from c e r t a i n streams i n B r i t i s h Columbia  143  Length-frequency d i s t r i b u t i o n of ammocoetes from the Salmon R i v e r , 1960-1963 ."  144  Growth of ammocoetes ( L. p l a n e r i ) i n the Salmon River during the years 1960-62.  145  Length-frequency diagram of Entosphenus l a r v a e , August 19, 1961.  147  Length-frequency of Entosphenus larvae from the N i c o l a and Thompson Rivers  149  Separation of polymodal frequency d i s t r i b u t i o n s of L. p l a n e r i ammocoetes using p r o b a b i l i t y paper (Salmon R i v e r , Sept. 9, 1962)  151  Separation of polymodal frequency d i s t r i b u t i o n s of- L. p l a n e r i ammocoetes using p r o b a b i l i t y paper (Salmon R i v e r , February 23, 1962)  152  61. 62. 63. 64. 65. 66.  67.  68.  Separation of polymodal frequency d i s t r i b u t i o n s of E . t r i d e n t a t u s ammocoetes using p r o b a b i l i t y paper ( Thompson and N i c o l a R i v e r s , Aug. 19, 1961) 153  Figure 69.  70.  Page Separation of polymodal frequency d i s t r i b u t i o n of E. t r i d e n t a t u s ammocoetes using p r o b a b i l i t y paper ( N i c o l a R i v e r , Aug. 2, 1962)  156  Growth curve of E. t r i d e n t a t u s , N i c o l a and 157  Thompson Rivers 72. 73« 74. 75.  154  Growth curve of L. p l a n e r i from the Salmon River  71.  .  Growth curves of B r i t i s h Columbia lampreys 158  ( N i c o l a and Salmon Rivers) Length-frequency diagrams of transforming l a r v a e , ammocoetes and adults of Lampetra and Entosphenus  163  A comparison of the s i z e and shape of transforming larvae of L. p l a n e r i  165  A comparison of the head of L. p l a n e r i  165  1  /  xi LIST OF TABLES Table  Page 1. Salmon River stream bottom types  9  2. Incidence of lamprey scars on trout i n E l s i e Lake  37  3. Fecundity and egg s i z e of B r i t i s h Columbia lampreys  49  4. A n a l y s i s of the depth of water and current v e l o c i t y above nests occupied by spawning adults i n the Salmon River  79  5. C o l l e c t i o n of emergent larvae from the Salmon R i v e r , J u l y 25, 1962  110  6. Bottom type preference of emergent from the Salmon River  113  larvae  7. Ammocoete b u r i a l rate i n the sand and mud i n a trough suspended i n the Salmon River  115  8. I n t e s t i n e a n a l y s i s of ammocoetes from the Salmon River  118  9» Summary of p r o b a b i l i t y paper a n a l y s i s of two c o l l e c t i o n s of L. p l a n e r i and E. t r i d e n t a t u s  155  1 INTRODUCTION  A study of the l i f e h i s t o r y and d i s t r i b u t i o n of Lampetra p l a n e r i (Bloch) and Entosphenus t r i d e n t a t u s (Richardson) was undertaken because of an almost complete absence of informa t i o n concerning the biology of these two species i n B r i t i s h Columbia. Stomach a n a l y s i s , bottom preference, d i s t r i b u t i o n w i t h i n the stream, and a s t a t i s t i c a l a n a l y s i s of the l e n g t h frequency data f o r the two species of lamprey were c a r r i e d out on the Salmon River populations during 1961 to 1963• Adult morphological c h a r a c t e r i s t i c s , f e c u n d i t y , spawning behaviour, and seasonal d i s t r i b u t i o n were a l s o observed on the study stream during t h i s period. Duration of the various l i f e stages from egg t o adult was attempted from the data c o l l e c t e d . The e c o l o g i c a l r e l a t i o n s h i p between the various stages of lamprey growth and the other community members i s discussed as w e l l as the s i g n i f i c a n c e of parasitica and nonp a r a s i t i c l i f e h i s t o r i e s from an evolutionary point of view. The major part of the study was c a r r i e d out on the Salmon River lamprey population. This r i v e r drains d e l t a farmland and flows i n t o the Fraser River near Fort Langley. The lamprey population i s an abundant f i s h form i n t h i s r i v e r at a l l seasons of the year and occupies the bottom h a b i t a t of mud and sand i n the pool areas of the r i v e r . Monthly c o l l e c t i o n s of lampreys were made during most of the time between 1961 and 1963.  P r e l i m i n a r y spawning behaviour observations were c a r r i e d  out i n aquaria i n the l a b o r a t o r y as w e l l as i n the stream f o r both species. Specimens of Lampetra were examined from Sweltzer  2 Creek (Cultus Lake), Port John Creek, Whonnoch Creek, Roberts Creek, Scott Creek, Tsolum R i v e r , and the B i g Qualicum River f o r comparison with the Salmon River p o p u l a t i o n . Due to the small population of Entosphenus i n the Salmon River {10% of spawning population) and the d i f f i c u l t y i n separating  the  ammocoetes, samples of adults of t h i s species were obtained from the Thompson, N i c o l a , B i g Qualicum, Stamp, C wichan, 0  Sweltzer, and Port John systems. Ammocoetes of t h i s  species  were c o l l e c t e d from the N i c o l a , Thompson, Tsolum, and B i g Qualicum R i v e r s . The l i f e h i s t o r y of Lampetra p l a n e r i i n Washington State has been studied by Schultz (1930). A survey of L . p l a n e r i and E. t r i d e n t a t u s was made i n the Cowichan River by C a r l (1953)• Lampetra p l a n e r i has been e x t e n s i v e l y studied i n Europe by Ivanova-Berg (1931), Knowles (1941), Zanandrea(1951, 1954, 1961), MacDonald (1949), and Hardisty (1944, 1951, 1961). Many other major studies have been undertaken on other  species  of lamprey p a r t i c u l a r l y i n Eastern North America. A basic pattern of s i m i l a r i t y of l i f e c y c l e seems to run through the groups. Lampreys are a s i g n i f i c a n t and i n t e r e s t i n g vertebrate group because they represent the lowest form of v e r t e b r a t e found i n fresh water lakes and streams as w e l l as being c l o s e l y r e l a t e d to the oldest vertebrate f o s s i l forms- the Ostracoderms from f r e s h water S i l u r i a n and Devonian remains. They are d i s t r i b u t e d widely i n the temperate regions of the w o r l d , being found i n North America, A u s t r a l i a , New Zealand, Europe, and  3  A s i a . Lampreys are not d i s t r i b u t e d i n the t r o p i c a l regions of the world nor i n A f r i c a or South America. Lampreys can be found i n most streams and r i v e r s along the  West Coast of North America. However they are best known  from the migrating schools of P a c i f i c lamprey r e t u r n i n g to r i v e r s i n the l a t e spring and f a l l . Lampreys have been c l a s s e d as p a r a s i t i c or n o n - p a r a s i t i c by Hubbs (1924), Zanandrea (1961), and Hardisty (1963), but some workers do not agree that lampreys are true p a r a s i t e s . F a c u l t a t i v e e c t o - p a r a s i t e may be a better term, but the o r i g i n a l terms that appear i n the l i t e r a t u r e w i l l be used throughout t h i s t h e s i s . The n o n - p a r a s i t i c brook lamprey i s seldom seen. The strong swimming a b i l i t y and sucking buccal d i s c enable lampreys to scale v e r t i c a l dams, w a t e r - f a l l s , and gorges that present impassible b a r r i e r s to other f i s h . The common species , Lampetra p l a n e r i and Entosphenus t r i d e n t a t u s , are d i s t r i b u t e d e x t e n s i v e l y i n the Fraser River system, Skeena R i v e r , streams of Vancouver I s l a n d , and i n many other major c o a s t a l r i v e r s . A t h i r d species, Lampetra a y r e s i (Gunther), a p a r a s i t i c lamprey, i s common i n the S t r a i t of Georgia during the summer months but only one specimen has been taken from f r e s h water. The d i s t r i b u t i o n of lampreys i n the province has been studied and recorded by C a r l , Lindsey et a l . ( 1 9 5 9 ) . Renewed i n t e r e s t i n the b i o l o g y of lampreys has occurred i n the l a s t ten years due to lamprey p a r a s i t i s m apparently being d i r e c t l y responsible f o r the removal of the lake t r o u t population from the Great  4 L a k e s o f E a s t e r n Canada. I n c i d e n c e Cowichan  o f p a r a s i t i s m on t r o u t i n  and E l s i e L a k e on V a n c o u v e r  on t h e i n c r e a s e d u r i n g r e c e n t y e a r s  I s l a n d has been r e p o r t e d (D.R.  Hurn- B r i t i s h  Columbia  F i s h and Game B r a n c h - p e r s o n a l c o m m u n i c a t i o n ) . T h i s l i f e  history  and p o p u l a t i o n a n a l y s i s o f t h e l a m p r e y s o f t h e S a l m o n R i v e r and o t h e r s y s t e m s , w i l l  provide the basis f o r f u r t h e r research  and f u r t h e r management o f t h e HISTORICAL AND  predator.  COMMERCIAL VALUE OF LAMPREYS  For c e n t u r i e s the Native Indians of B r i t i s h  Columbia  h a v e u s e d l a m p r e y s as f o o d i n t h e smoked, s u n d r i e d , and form. Indians at Moricetown F a l l s and a t L i l l o o e t  on t h e S k e e n a R i v e r ( F i g . l )  on t h e F r a s e r R i v e r c a t c h l a m p r e y by  their traditional  salted  s a l m o n d i p n e t s w i t h f i n e meshed  lining  webbing.  The l a m p r e y a r e e a s i l y s c o o p e d f r o m t h e c a n y o n w a l l s as  they  c l i n g t o t h e w a l l s o r t o each o t h e r i n g r e a t numbers. I n  1948  i t was  the  r e p o r t e d t h a t m a s s e s o f l a m p r e y s f o r m e d mats a l o n g  w a l l s o f H e l l ' s G a t e Canyon and L i l l o o e t R a p i d s t o a d e p t h o f at  l e a s t a foot of entangled K i n g Henry  bodies.  I of England enjoyed e a t i n g the p r i m i t i v e  but  t a s t y l a m p r e y s t o s u c h an e x t e n t t h a t h i s i n g l o r i o u s d e a t h i s a t t r i b u t e d t o e a t i n g t o o many a t one Little  o r no c o m m e r c i a l use i s made o f t h e l a m p r e y s o f  B r i t i s h C o l u m b i a . A few European  immigrants at A l b e r n i catch  the a d u l t l a m p r e y s as t h e y m i g r a t e and c a n y o n . The m i g r a t i n g f i s h to  meal.  up Stamp F a l l s f i s h  a r e c a u g h t by h o o k s  a l o n g p o l e , much l i k e a h e r r i n g j i g . The  a r e o c c a s i o n a l l y used as b a i t  ladder  attached  l a r g e r ammocoetes  by t r o u t f i s h e r m e n  because  they  t  5 m a i n t a i n v i g o r o u s body movements f o r a l o n g time when b a i t e d on a hook. The Chinese community i n Vancouver m a i n t a i n t h a t ammocoetes are the b e s t b a i t f o r s t u r g e o n i n t h e F r a s e r S c h u l t z (1930) r e p o r t e d t h a t lamprey i n t h e S e a t t l e a r e a  River. are  s o l d e x t e n s i v e l y f o r t r o u t b a i t . P i k e (1953) r e p o r t e d t h a t Willamette F a l l s ,  at  (Oregon) up t o 200 t o n s o f lamprey a r e t a k e n  f o r r e d u c t i o n purposes d u r i n g t h e a n n u a l s p r i n g m i g r a t i o n . A s m a l l c a n n i n g o p e r a t i o n uses Petromyzon i n O n t a r i o t o spiced,  smoked, and f l a v o u r e d d e l i c a c i e s .  produce  Great numbers of  a d u l t lampreys can be o b t a i n e d a t w e i r dams i n t h e r i v e r s by i n s e r t i n g v e r t i c a l boards w i t h w a t e r r u n n i n g over t h e The lamprey c l i m b t h e s e boards and f a l l  boards.  i n t o baskets at  the  t o p . P o s s i b l y lamprey w i l l be more f u l l y u t i l i z e d as a food source i n t h e  Fig. 1  future.  P a c i f i c lamprey d r y i n g i n t h e sun at M o r i c e t o w n on t h e B u l k l e y R i v e r .  6  DESCRIPTION OF THE STUDY AREA Lampreys were c o l l e c t e d mainly i n the Salmon River and a d j o i n i n g streams and on Vancouver I s l a n d , as i n d i c a t e d by F i g . 2. Lampreys occur i n streams that have a large number of pool areas where sediments can s e t t l e , interspaced with areas of g r a v e l . Streams with a steep gradient and l i t t l e or no pool area are u s u a l l y not occupied by lampreys. However, the upper reaches of a stream may be f i l l e d with rapids and  no  sediment areas, yet the lower reaches, l e s s than one mile from the sea, may be occupied by lampreys as i s the case, f o r example, i n Roberts Creek. A. P h y s i c a l D e s c r i p t i o n of the Salmon River 1. Mapping and S t a t i o n s See Figures 2 and 3« 2. Drainage The Salmon River drains d e l t a and plateau farm and wooded area i n the Lower Fraser V a l l e y ( F i g . 2 and 3)«  The  drainage basin l i e s at an e l e v a t i o n of l e s s than 300 f e e t . The drainage area from Jardine to the r i v e r mouth ( F i g . 3) has been subject to p e r i o d i c f l o o d i n g by the Fraser River i n the recent past as the s o i l s are a l l u v i a l underlain by c l a y . This s e c t i o n of the r i v e r has stable banks and a mud  bottom.  Few lampreys are found i n t h i s s e c t i o n of the stream as i t contains no gravel areas f o r spawning and ammocoetes washed down by f l o o d i n g are u s u a l l y deposited f u r t h e r upstream. From Jardine to Coglan Creek j u n c t i o n the s o i l s are c l a y  7  l.  Salmon R i v e r 2. S c o t t C r e e k 3. Whonock C r e e k k.. S w e l t z e r C r e e k 5. S m i t h C r e e k 6 . Robert's C r e e k 7 . Stamp R i v e r o. E l s i e Lake Cowichan Lake . B i g Qualicum R i v e r . N i l e Creek . Tsolum R i v e r . Hook Nose Creek' . Moricetown F a l l s . H e l l s Gate R a p i d s . Nicola River . Thompson R i v e r . L i l l o o e t t Rapids . Bridge R i v e r Rapids . Fraser River , Alouette River R i v e r , L a k e o r Creek.  LANGLEY  Fig,. 2 Rivers and streams i n Br were c o l l e c t e d and studied  preys  8  FIG. 3. COLLECTING  STATIONS  ON THE  SALMON  R.  loams underlain by dense c l a y (KeHey and S p i l s b u r y 1939). Ammocoetes are very abundant i n the large pool areas of t h i s s e c t i o n of the r i v e r and adult Lampetra and Entosphenus are found above the r i f f l e areas during the spawning  season  ( F i g . 4 and 5). The stream bottom types are shown' i n Table 1. Table 1  Salmon River Bottom Types (McMynn and Vernon Section of Stream  T o t a l length of stream system  Miles . 22.3  1954)  Percent 100  Length of stream with unstable banks and no tree cover Length of semi-permanent portions Length of permanent p o r t i o n  11.8  53-0  4.3  19-4  18.0  80.6.  Length of permanent stream with unstable banks and no t r e e cover Length of permanent stream with s t a b l e banks and t r e e cover  7. 5  33-6  10.5  47.0  The s e c t i o n of the r i v e r from Coglan Creek j u n c t i o n to above s t a t i o n 5 c o n s i s t s of sand and gravel loams underlain with clays (Keely and S p i l s b u r y 1 9 3 9 ) . A moderate gradient e x i s t s and 30 to 40 percent of the bottom c o n s i s t s of g r a v e l and stones (McMynn and Vernon 1954). Small pool areas occur i n t h i s s e c t i o n of the stream where s i l t , sand, and f o r e s t debris are deposited.. Spawning was observed throughout t h i s s e c t i o n of the r i v e r and ammocoetes were found i n the pool and sand bar areas but they were not as densely concentrated.as at s t a t i o n 1. The stream bottom between s t a t i o n s 5 and 1 i s semi-  10  Fig. 5  Pool area o f the Salmon R i v e r below s t a t i o n 1. X = areas where ammocoetes may be c o l l e c t e d .  11 permanent as f l o o d i n g i s c o n t i n u a l l y s h i f t i n g i t s p o s i t i o n . The lower t r i b u t a r y from s t a t i o n 7 to the mouth d i d not contain lampreys. Many sediment deposits containing ammocoetes have formed and disappeared during the study period i n the stream above Jardine. 3. Flow A water gauge was located at s t a t i o n 1 and the Water Resources Branch of the Department of Northern A f f a i r s and National Resources recorded the d a i l y flow throughout the study period. The greatest discharge of water from the Salmon River u s u a l l y occurs between December and February. A maximum discharge of 720 cubic f e e t per second (Second-feet) was recorded on December 3 0 , 1962, at s t a t i o n 1, and the minimum discharge of 4-2 second-feet was recorded on A p r i l 28, 1963 (Figures 6, 7, and 8 ) . However, i n the two previous years the lowest discharge occurred i n the June t o September periods. Farms bordering the r i v e r pump water from the Salmon River during the summer which tends-to reduce the flow s t i l l f u r t h e r . 4. Temperature An automatic temperature recorder (Weksler) was maintained by the B r i t i s h Columbia.Fish and Game Branch during 1961 and 1962 at s t a t i o n 1. I n d i v i d u a l temperature readings were taken with a f i e l d thermometer whenever the stream was v i s i t e d i n 1963. The comparison of maximum weekly water temperature and mean weekly discharge i s graphed (Figures 6,7,and 3) f o r the three years of the study. The maximum water temperature  OCT.  NOV.  DEC.  JAN.  FEB.  MAR.  APR.  MAY  JUNE  JULY  AUG.  SEPT.  FIG.6. M E A N W E E K L Y D I S C H A R G E A N D M A X I M U M W A T E R T E M P E R A T U R E ( S A L M O N R., STATION I; I960 - 61)  FIG. 7. M E A N W E E K L Y DISCHARGE AND MAXIMUM FOR THE SALMON RIVER (STATION I, 1961-62 )  WATER  TEMPERATURE  15 u s u a l l y occurs i n June or J u l y and the lowest water  temperature  occurs i n January or February. B. B i o l o g i c a l D e s c r i p t i o n of the Stream 1. Plant Cover The e n t i r e drainage area was o r i g i n a l l y covered w i t h dense coniferous f o r e s t , except f o r a small f l o o d p l a i n near the mouth. The land above the f l o o d p l a i n was cleared f o r a g r i c u l t u r a l purposes during the l a s t h a l f century (McMynn and Vernon 1954)• The second growth Douglas F i r (Pseudotsuga t a x i f o l i a ) , Western Red Cedar (Thuja p l i c a t a ) , Western Hemlock (Tsuga h e t e r o p h y l l a ) , Broad Leaf Maple (Acer macrophyllum), and Red Alder (Alnus rubra) were replaced by crops of strawb e r r i e s and hay. The r i v e r banks are l i n e d w i t h Vine Maple (Acer c i r c i n a t u m ) , B i t t e r Cherry (Prunus emarginata), Cascara (Rhamnus purshiana), Northwest Willow ( S a l i x s e s s i l i f o l i a ) , Western Red Cedar and Red A l d e r . The undercover along the stream c o n s i s t s of Salmon Berry (Rubus s p e c t a b i l u s ) , Thimbleberry (Rubus p a r v i f l o r u s ) , T r a i l i n g Blackberry (Rubus V i t i f o l i u s ) , Red Elderberry (Sambucus C a l l i c a r p a ) , and S t i n g i n g Nettle (Urtica l y a l l i i ) . . 2. Aquatic P l a n t s Sewage b a c t e r i a (Sphaerotilus) were, very abundant during the summer months i n the Salmon River. Spirogyra and other filamentous pond algae were common i n the back water areas and stream bottom during the warmer period of the year. A great v a r i e t y of diatoms and some desmids were observed t o  16  i n h a b i t the r i v e r water throughout the year, as was  evident  from a n a l y s i s of lamprey i n t e s t i n e s . Rooted aquatics were represented  by  Anacharis,  Ranunculus, and Potamogeton i n the deeper permanent pools of the r i v e r . Great q u a n t i t i e s of plant debris accumulated p a r t i c u l a r l y i n the f a l l and was buried i n the pool area  and  sand bars. This m a t e r i a l decays at a slow r a t e , but o f f e r s a refuge and p o s s i b l e food source f o r l a r g e r ammocoetes. 3 . Animal L i f e McMynn and Vernon  (1954)  sampled the bottom fauna  of the Salmon River during the winter and summer and my r e s u l t s agree favourably w i t h t h e i r data. They found Ephemeroptera to be the most abundant group followed i n abundance by Plecoptera, D i p t e r a , Trichoptera, Annelida, and  Coleoptera,  Planorbidae.  They n o t i c e d (as was v e r i f i e d ) a r i s e i n numbers of bottom organisms a f t e r December with a peak i n numbers occurring i n A p r i l . A s c a r c i t y of bottom fauna was  p a r t i c u l a r l y noticed  during the winter f l o o d i n g period. Fresh water clams were p a r t i c u l a r l y abundant from s t a t i o n 2 to the mouth of the r i v e r . The c r a y f i s h (Pacifastacus l e n i u s c u l u s ) i s abundant, but c o l l e c t e d only during the summer and f a l l , and occupies  was a  h a b i t a t s i m i l a r to the lamprey l a r v a e . The Salmon River supports an abundant f i s h population. Lampreys are the most abundant vertebrate residents i n the r i v e r throughout the year. Coho Salmon (Oncorhynchus kisutch) are present i n f i v e times the density of the other salmonids combined (McMynn and Vernon  1954).  The s t i c k l e b a c k (Gasteroseus  17  .  aculeatus) i s a permanent resident throughout the  stream.  A number of other f i s h species that are r e s t r i c t e d to one part of the stream, or occur only during one part of the season are Steelhead t r o u t (Salmo g a i r d n e r i i g a i r d n e r i i ) , cut-throat t r o u t (Salmo c l a r k i i c l a r k i i ) , p r i c k l y s c u l p i n (Cottus asper), and the l a r g e s c a l e sucker (Catostomus macrocheilus). METHODS AND PROCEDURES A. C o l l e c t i n g Methods f o r Ammocoetes Emergent ammocoetes were c o l l e c t e d by using a modified Surber Sampler placed i n the r i f f l e area of the stream below a spawning l o c a t i o n . The sampler was  modified  by g l u i n g a l i n e r made from a knotted nylon stocking i n t o the c o l l e c t i n g mesh of the sampler. This produced f o l d s and a very f i n e mesh so that the water pressure d i d not f o r c e the d e l i c a t e bodies of the newly hatched ammocoetes through the mesh. The sampler was placed i n the stream and emptied every eight hours. F l a t aluminum t r a y s (25 mm. w i t h f i n e mud  by 38 mm.)  were f i l l e d  and placed i n various l o c a t i o n s i n pools and  gravel areas to catch ammocoetes that were being c a r r i e d downstream. The l a r v a e buried i n t o the mud  of the t r a y s and were  counted at eight hour i n t e r v a l s when the t r a y s were removed. The m a j o r i t y of the ammocoetes of a l l year c l a s s e s were' dug from the bottom of the r i v e r w i t h a sturdy scoop attached to a long handle ( F i g . 9 and 11). The dimensions of the frame of the scoop are 24 x 20 x 20 x 12 cm. and 1.5  mm.  p l a s t i c mesh served as screening. A standard scoop of bottom  18 ( F i g . 10) was obtained by digging 8 cm. of the surface over 1 metre of the bottom (approximately 2 l i t e r s of sand per scoop). The sediments were u s u a l l y placed on an i n c l i n e d plywood box and the ammocoetes were removed by hand and subsequently  preserved i n 2% f o r m a l i n .  Figure 9. C o l l e c t i n g equipment: A. ammocoete scoop. B. Adult scoop. C. Plywood box used to sort l a r v a e from bottom sediments. B. C o l l e c t i n g Methods f o r Adults A portable 400 v o l t p u l s a t i n g square wave d i r e c t current e l e c t r i c shocker (0-L E l e c t r o n i c Shocker, Oceanic Instruments Inc.) was used once to c o l l e c t prespawning a d u l t s hiding i n the gravel at the end of  l a r g e pools ( F i g . 11).  An eight foot siene was used to c o l l e c t the g r a v e l areas at the end of large pools and the r i f f l e areas. The  seine  was held downstream by one person while the other turned over rocks upstream with a shovel. Sweeps of the pools and bottom areas with the seine were also c a r r i e d out.  F i g . 11 Method used to c o l l e c t adults and l a r g e l a r v a e above a r i f f l e area. E l e c t r i c shocker being used.  20  Adults spawning i n nests were captured with a large scoop ( F i g . 9-B)  that was  q u i c k l y drawn over the nest removing  the lampreys and g r a v e l . P a r t i c u l a r care must be taken on b r i g h t sunny days to move slowly but to perform the  scooping  operation q u i c k l y as the animals are e a s i l y frightened at t h i s time. RESULTS AND  REVIEW OF LIFE HISTORY  A. Review of the Taxonomy of the B r i t i s h Columbia Lampreys 1.  I d e n t i f i c a t i o n of Adults By D e n t i t i o n The d i f f e r e n t i a t i o n between adults of Lampetra  p l a n e r i and Entosphenus t r i d e n t a t u s i s f a c i l i t a t e d by the presence of blunt degenerate teeth i n the n o n - p a r a s i t i c Lampetra while the p a r a s i t i c Entosphenus has sharp rasping teeth ( F i g . 12 and 1 $ ) .  Figure 1$ shows the v a r i a t i o n i n the  cusps on the l a t e r a l teeth of Entosphenus. The drawings ( F i g . 13 and 16)  schematic  show the d i f f e r e n c e i n number and  p o s i t i o n by d e n t i t i o n that appears commonly i n the two Salmon River species. The supraoral l a m e l l a of Entosphenus has  three  cusps; Lampetra has only two, while the i n f r a o r a l l a m e l l a i n the former has 5 cusps, but 7 cusps i n the l a t t e r . Entosphenus has 4 to 5 l a t e r a l teeth while Lampetra has three. By Myotomes The adult myotomes were counted under a d i s s e c t i n g microscope. The adults had to be skinned and stained with eosin on occasions when counting from e x t e r n a l features d i f f i c u l t . The count was taken between the l a s t g i l l  was  cleft  21  F i g . 12. Buccal d i s c and tooth morphology o f the n o n - p a r a s i t i c lamprey L. p l a n e r i from the Salmon R i v e r . Supra-oral(2A) and sub-oral(2Bj l a m e l l a with the d i s c and l a t e r a l teeth removed. S a g g i t a l section!3) through the buccal d i s c showing the l a t e r a l t e e t h , each with two cusps (3C).  SALMON  RIVER FORM  EUROPEAN FORM (REDRAWN ZANANDREA 1961)  F i g . 13. Schematic drawings o f the buccal d i s c o f the Salmon River and European L. p l a n e r i .  F i g . 14. Comparison of B r i t i s h Columbian and European ammocoetes of L. p l a n e r i by areas o f pigmentation.  22  F i g . 15 Buccal d i s c and tooth morphology of the p a r a s i t i c lamprey E. t r i d e n t a t u s from the Salmon River.  F i g . 16 Schematic drawing of the d i s c and d e n t i t i o n of E. t r i d e n t a t u s from the Salmon River.  23 and the a n t e r i o r edge of the u r o g e n i t a l opening. There was a s i g n i f i c a n t d i f f e r e n c e i n myotome counts between the adults of the two species ( Fig.1,7 mean L. p l a n e r i 63.9  and E. t r i d e n t a t u s 66.9;  T = 10.53, P <.001). This  represents a higher myotome range 62-69 f o r L. p l a n e r i compared t o a 60-65 range reported by Hubbs (1924) and C a r l et al.(195$). :  2. I d e n t i f i c a t i o n of Ammocoetes I d e n t i f y i n g ammocoetes of B r i t i s h Columbia lampreys has been very d i f f i c u l t as a myotome count has been the only c r i t e r i o n used (Carl et al.1959)• A l l ammocoetes were skinned on the r i g h t side and counts made under the microscope. Skinning was accomplished by making two p a r a l l e l cuts along the s i d e of the animal from the l a s t g i l l opening to j u s t past the vent. Then the s k i n was  s t r i p p e d from the side with forceps. S t a i n i n g  the ammocoete connective t i s s u e with eosin helped i n making accurate myotome counts. Vladykov (1955) reported that on the average ammocoetes possessed 1 or 2 fewer trunk myotomes than a d u l t s . Counts of myotomes are most d i f f i c u l t on a d u l t s . Adult Entosphenus do not increase t h e i r myotome numbers on reaching adulthood as i s common f o r Lampetra i n the Salmon River and i n other species reported by Vladykov (1955)-  Figure  17A and 17B shows the range of v a r i a t i o n i n the myotome number f o r the adults and ammocoetes from the Thompson-Nicola system ( e x c l u s i v e l y Entosphenus)and those of the Salmon R i v e r , a mixed population containing mainly Lampetra (90-95% of spawning a d u l t s ) . Myotome counts on 45 ammocoetes of t'  Entosphenus (range 65 to 71, mean 67.5)  showed a h i g h l y  s i g n i f i c a n t d i f f e r e n c e from Lampetra ( range 59 to 65,  mean  24 fl  60  65  NUMBER  OF  LAMPETRA  <K=62.3>  70 MYOTOMES  FIG.I7A.M Y O T O M E  NUMBER IN A M M O C O E T E S  NUMBER  OF MYOTOMES LAMPETRA  FIG.I7SMYOTOME  NUMBER  ENTOSPHENUS  IN  ADULTS  25  62.3)  T =  19-3,  P = .001,  95  df. •  The separation of the i n d i v i d u a l s with overlapping myotome numbers was accomplished by comparing the areas of the ammocoetes covered by melanophores ( F i g . 18). Vladykov . and F o l l e t t (1958) maintain t h a t , " one of the most important characters f o r the i d e n t i f i c a t i o n of l a r v a l lampreys i s the pigmentation of the head and t a i l region." Care must be taken to have the melanophores i n the same stage of c o n t r a c t i o n to make t h i s method c o n s i s t e n t . The increase i n melanophores on two areas of the head of Lampetra i s a d i s t i n c t c h a r a c t e r i s t i c i n separating the l a r g e r ammocoetes of the two species. Small ammocoetes do not show the same d i s t i n c t d i f f e r e n c e s and can not be separated on the basis of pigmentation. Figure 17B represents myotome counts of Lampetra from the Salmon River and Entosphenus from the N i c o l a , Thompson, and Cowichan R i v e r s . Four of the ammocoetes with higher myotome counts from the Salmon River ammocoetes proved to be Entosphenus when melanophores were observed ( F i g . 17A). 3 . Nomenclature A key t o Western North American lampreys appears i n C a r l et a l . (195$). The i d e n t i f i c a t i o n and nomenclature of Entosphenus t r i d e n t a t u s and Lampetra ayresi. produces no d i f f i c u l t y f o r the adult but separation of the ammocoetes i s not p o s s i b l e from the myotome counts given. The nomenclature a p p l i e d to L. p l a n e r i showed much discrepancy with the European form so.the o r i g i n a l naming was traced. The f i r s t d e s c r i p t i o n of the North Western Brook lamprey was attempted by Creaser & Hubbs (1922) and was based on the d e s c r i p t i o n of Regan (1911)  26  ENTOSPHENUS NICOLA  TRIDENTATUS  RIVER  100 mm.  101 mm.  Melanophores reduced below the g i l l s l i t s  COWICHAN  RIVER  95 mm.  85 mm.  Clear area above 1st gill slit  LAMPETRA SALMON  PLANERI RIVER  96 mm,  88mm.  Fig.  No c l e a r area above 1st g i l l slit  Melanophores extended below g i l l slit  18 Shows how the melanophore pattern can be used t o d i s t i n g u i s h large ammocoetes of E. t r i d e n t a t u s from L. p l a n e r i . )  27 from specimens taken from Europe, S i b e r i a , and Japan. The name Lampetra p l a n e r i was adopted because the middle l a t e r a l tooth has two or three cusps, according to Regan (1911). Since t h i s time the specimens w i t h two cusps have been renamed L. mariae and L. r e i s s n e r i i n Europe and Asia while L. w i l d e r i a p p l i e s i n Eastern North America (Berg, 1931)• However f o r the lampreys from Western North America the s p e c i f i c name p l a n e r i has been r e t a i n e d . A re-examination of the genus Lampetra would seem t o be d e s i r a b l e . 4- Comparison of European and B r i t i s h Columbia L. p l a n e r i The number of cusps on the middle l a t e r a l tooth of the Salmon River L. p l a n e r i ranged from none t o three w e l l developed cusps ( F i g . 1 2 ) . Three i n d i v i d u a l s from the Salmon River possessed two cusps of the middle l a t e r a l s on one side and three on the other s i d e , while on two others the l a t e r a l s were missing completely. However, two cusps on the middle l a t e r a l tooth was the average number f o r adults from the Salmon River and Sweltzer Creek.while adults from Port John Creek had an average of three cusps. The middle l a t e r a l tooth cusps always numbered three i n the European L. p l a n e r i . The myotome number of the adult European L. p l a n e r i v a r i e d from 60 t o 65 (mean 6 2 . 3 ) Vladykov (1955), while i t s ammocoetes ranged from 58 t o 64 (mean 60.7). The Salmon River population had higher counts of myotomes, 61 t o 65 (mean 63•4) f o r a d u l t s while the ammocoetes had 58 t o 65 (mean 6 2 . 3 ) . The melanophore area of the head and t a i l of the European L. p l a n e r i ammocoete was g r e a t l y reduced compared t o areas of the North American form ( F i g . 1 4 ) .  28 There'seemed to be a greater degree of sexual dimorphism i n the European form than i n the Salmon River form because d o r s a l f i n height, eye diameter, and buccal d i s c diameter showed only s l i g h t d i f f e r e n c e with sex compared t o marked sexual, d i f f e r e n c e s i n the European forms  (Vladykov,1955)•  B. Adult L i f e 1. Duration of Adult L i f e A d u l t . l i f e commences when metamorphosis i s complete and when the adult morphological c h a r a c t e r i s t i c s appear.  ^  Metamorphosis, i s the t r a n s i t i o n period when the ammocoete undergoes drastic.; body changes such as the formation of a sucking buccal d i s c with t e e t h , formation of f u n c t i o n a l eyes, development of two d o r s a l f i n s , atrophy of the endostyle, enlargement of the gonads, and abandoning of f i l t e r  feeding,  plus many other p h y s i o l o g i c a l and morphological changes. From length-frequency data adult l i f e apparently s t a r t s a f t e r at l e a s t f i v e years of l a r v a l l i f e . Further morphological changes take place during transformation and adult l i f e f o r at l e a s t one year. Leach (1940) i s of the opinion that there i s a r e s t period p r i o r t o metamorphosis, when the ammocoete does not grow i n l e n g t h . S t a u f f e r (1962) found evidence of a longer l i f e c y c l e than was i n d i c a t e d from length-frequency data when he allowed a Sea Lamprey population t o go t o e x t i n c t i o n . A r e s t period has been found i n a l l cases examined experimentally. It i s h i g h l y l i k e l y t h e r e f o r e that the Salmon River population and other B r i t i s h Columbia lampreys are at l e a s t one year older than i s i n d i c a t e d from the length-frequency a n a l y s i s of the population.  I  29  Lampetra Transforming  ammocoetes appear i n the c o l l e c t i o n s  from the Salmon River during August to November, with f u l l y transformed  adults appearing on the spawning gravel i n A p r i l .  No specimens of transforming adults have been found i n the r i v e r from December to A p r i l so l i t t l e can be said about the exact time adult l i f e s t a r t s . However, one p a r t l y metamorphosed female was obtained as l a t e as A p r i l 29. The d i s c was  buccal  incompletely formed and no female secondary sex  c h a r a c t e r i s t i c s were present. This specimen was kept i n an aquarium ( l 6 - 2 0 ° C ) . By the f i r s t of June the abdomen was distended from the enlarging eggs and a pseudoanal f i n had developed. However, the animal remained buried i n the gravel u n t i l the sexual development was complete, suggesting that transforming adults burrow deeply i n t o the g r a v e l during the winter and leave the g r a v e l only when sexual maturity i s completed i n the s p r i n g . C o l l e c t i o n from the Salmon River of four a d u l t s nearing sexual maturity but s t i l l burrowed i n the g r a v e l was accomplished May 1962.  by using an e l e c t r i c shocker i n  These specimens had j u s t a t t a i n e d sexual maturity  as one female had .not shed her eggs and her body was  distended.  When placed i n an aquarium, communal spawning s t a r t e d w i t h i n two days. Hence adult l i f e appears to l a s t for. only a matter of one or two weeks before spawning. Females u s u a l l y die w i t h i n a week of l a y i n g a l l eggs, but they can l i v e f o r one month at low temperatures (8-14°C) as w i l l be described i n the post spawning period observations. Males may two months a f t e r spawning.  l i v e as long as  Entosphenus  30  The Brook lamprey achieves sexual maturity  immediately  a f t e r transformation, spawns and d i e s ; but the p a r a s i t i c lamprey, Entosphenus, migrates t o sea at the s t a r t of adult l i f e . The migration t o sea takes place during the s p r i n g and summer i n B r i t i s h Columbia. Entosphenus begins to feed p a r a s i t i c a l l y on the blood of f i s h e s upon entry to the sea or lake and develops a l a r g e a b o r t i v e i n t e s t i n e . In the Salmon River population metamorphosis probably occurs during the summer and f a l l of the f i f t h year of l i f e or l a t e r . Specimens of transforming Entosphenus were taken from the Big Qualicum River during August 1961 and from the N i c o l a River i n December of the same year, i n d i c a t i n g that migration downstream occurs during the summer f o l l o w i n g transformation. Small mature adults apparently migrating downstream were c o l l e c t e d on the i r r i g a t i o n screens of the N i c o l a River during August. From the s i z e of adults attached t o f i s h i n the S t r a i t of Georgia and i n Cowichan Lake i t can be deduced that p a r a s i t i s m begins during the spring and summer f o l l o w i n g migration to the sea or l a k e . No evidence e x i s t s on the P a c i f i c Coast f o r p a r a s i t i s m by the lamprey during the f i r s t year of adult l i f e but they p o s s i b l y feed on species of f i s h that are slow swimming and bottom feeders r a t h e r than on salmonids which are preyed upon by l a r g e lampreys. The s i z e of scar marks on hosts and the s i z e of specimens c o l l e c t e d i n d i c a t e a f u r t h e r stay of one year i n the sea with migration upstream commencing during the summer and f a l l of the f i r s t or second year of sea  31 or l a k e l i f e .  P r e c o c i t y i s suggested  by s m a l l s i z e d members  of the p o p u l a t i o n s i n the Salmon R i v e r and N i l e Greek (Vancouver I s l a n d ) . M i g r a t i o n upstream may advance of spawning. Applegate  o c c u r one year i n  (1950) suggests  t h a t the  Sea  Lamprey o f E a s t e r n North America spends two years of a d u l t life  i n t h e s e a . Recent d i v i n g o b s e r v a t i o n s by Mansuet (1962)  suggest t h a t the Sea Lamprey, upon m i g r a t i o n t o the sea, spend the w i n t e r of the f i r s t year i n the shore f e e d i n g on s m a l l bottom and menhaden. Atrophy  e s t u a r i e s near the  shore f i s h e s such as  of the mid-gut and  the  i n t e s t i n e occurs upon  e n t r y t o f r e s h w a t e r , and no f e e d i n g o c c u r s d u r i n g the preceding  may  year  spawning. Some specimens of Entosphenus spend the w i n t e r  and  e a r l y s p r i n g among r o c k s and g r a v e l i n the upper reaches of B r i t i s h Columbia streams.  One  specimen was  collected  during  December, 196l, at M e r r i t t on the N i c o l a R i v e r w h i l e t h e w r i t e r was to  t u r n i n g over some l a r g e b o u l d e r s . A s h o r t m i g r a t i o n  l o c a t e spawning g r a v e l i s s u s p e c t e d o ,  i n A p r i l t o June, when  the t e m p e r a t u r e r i s e s above 10 C (from o b s e r v a t i o n s on Salmon R i v e r ) . Few  the  a c t u a l o b s e r v a t i o n s o f Entosphenus spawning  have been w i t n e s s e d and a p p a r e n t l y no d e s c r i p t i o n s of spawning behaviour  occur i n the  literature.  .2. Length o f A d u l t s Ammocoetes and a d u l t s were measured t o the mm.,  by p l a c i n g the a n i m a l s over a p l a s t i c r u l e r and  nearest reading  the d i s t a n c e from the t i p of the o r a l hood t o the t i p of the tail.  A s h r i n k a g e of 3 p e r c e n t o c c u r r e d a f t e r a p e r i o d of  p r e s e r v a t i o n of one month from the i n i t i a l  measurements.  32 The l i v e animals were f i r s t measured a f t e r a n a e s t h e t i s a t i o n with MS 222 (0.2 gr. per l i t e r ) . Lampetra Adult lampreys from the Salmon River are much shorter i n length than those of Smith Creek and Hooknose Creek (see F i g . 19A). The.mean length i s 120.mm. f o r the Salmon River and 143.8 mm. and 167-2 mm. f o r the other streams r e s p e c t i v e l y . Schultz (1930) c o l l e c t e d 126 adults (mean 110 mm.) near S e a t t l e , Washington. These.Lampetra are much smaller than any of the populations i n B r i t i s h Columbia. Hardisty (1944) found considerable v a r i a t i o n i n the s i z e of adults from d i f f e r e n t streams and even from d i f f e r e n t parts of the same stream f o r L. p l a n e r i i n England. He found a d i f f e r e n c e of 20 mm. between means of some populations but the mean over a ten year period was 132 mm. The v a r i a t i o n i n length over a wide range (83169 mm.) i n the Salmon River population seems to be a general c h a r a c t e r i s t i c of lamprey populations as reported by Applegate (1950) and Zanandrea (1954). Hardisty (I96la) suggests that t h i s spread i n s i z e represents mixed spawning classes as i s also i n d i c a t e d from the length-frequency  data. Two or three  modes may occur i n separate age c l a s s e s . However n u t r i t i o n a l or environmental e f f e c t s on length was i n d i c a t e d by the great range i n length i n L . p l a n e r i i n the Salmon River ( F i g . 24). The upstream a d u l t s are s i g n i f i c a n t l y smaller i n length than the downstream i n d i v i d u a l s which suggests d i f f e r e n c e s i n nutrition.  33  100 LENGTH  IN  120 MM  KO  LENGTH-FREQUENCY LAMPETRA PLANERI ,  FIG.isA.  160  180  DIAGRAMS OF ADULT  NILE C R E E K 7. - 2 0 4  STAMP X = 313  3 Q < U.  o UJ CD  RIVER  —i— 25  30  35  •L i  20  COWICHAN X = 284  LAKE  25  537  D Z  SALMON 7=  20  30  25 LENGTH  IN  35  RIVER  281  40  45  CM  LENGTH-FREQUENCY DIAGRAMS OF ADULT ENTOSPHENUS TRIDENTATUS  FIG.198.  34  Entosphenus The Entosphenus spawning population on the Salmon River a l s o shows a wide range i n s i z e when compared t o the migrating a d u l t s c o l l e c t e d on the Stamp R i v e r . Since t h i s species i s anadromous and p a r a s i t i c there i s greater n u t r i t i o n a l v a r i a t i o n than might be expected i n the sedentary Brook Lamprey. The v a r i a t i o n i n length i s from 193 to 450 mm. with a mean of 281 (See F i g . 16 & 19). Inadequate sample s i z e from t h i s rather small percentage of t h e Salmon R i v e r lamprey population (5-10%) l i m i t s the conclusions that can be drawn, but there i s an i n d i c a t i o n from the histogram ( F i g . 19) that two d i s t i n c t s i z e groups may be present. I t i s p o s s i b l e that some i n d i v i d u a l s return from the sea prematurely  F i g . 20: A. B. C. D. E.  Differences i n s i z e s of Entosphenus A distended 410 mm. specimen from Port John A 33O mm. migrating adult from the Stamp River A 183 spawning female from the Salmon River Metamorphosing adult from N i c o l a River Metamorphosing adult from B i g Qualicum River  35  because they may migrate to the Fraser River or e s t u a r i e s , while the- l a r g e r s i z e adults may spend a greater number of years l i v i n g p a r a s i t i c a l l y on f i s h e s i n the open sea. Examination of specimens caught i n the S t r a i t of Georgia suggest the p o s s i b i l i t y of a small s i z e group ( F i g . 1 9 ) . The s i z e of lamprey scars on whales (Pike, 1951) and from one large specimen (570 mm.) taken from the mouth of a f u r s e a l many miles o f f Cape F l a t t e r y , suggests that l a r g e r lampreys go many miles i n t o the open ocean. C a r l et a l .  (1959)  suspect that a dwarf race of  Entosphenus i s present i n the .Cowichan River system. An a n a l y s i s of 6 specimens attached to t r o u t from Cowichan Lake diswed a mean length of 226 mm. These animals were probably i n t h e i r second year of adult l i f e as i n d i c a t e d from t h e i r gonads and i n t e s t i n e s . They p o s s i b l y represent a land-locked race of lamprey that spends i t s e n t i r e l i f e i n Cowichan Lake and i s s i m i l a r to the land-locked lamprey of the Great Lakes. However, one specimen 537 mm. i n length was c o l l e c t e d attached t o a log  during June of 1961. On examination  i t was determined that  t h i s represented a migrating adult r e t u r n i n g from the sea (Fig.  23).  Carl  (195.3  ) reported a l a r g e migrating run of  Sea Lamprey that formerly ascended Scutt F a l l s i n August. No reports of t h i s l a r g e run have been made i n recent years. A landlocked p a r a s i t i c race of lamprey may be present i n the r e c e n t l y impounded E l s i e Lake near A l b e r n i (D.R. ,Hurn, personal communication). Hurn reported a 76 percent incidence of lamprey p a r a s i t i s m on the t r o u t population i n t h i s lake i n May (Table 2 ) . His n e t t i n g of t r o u t showed an  36  increase of f r e s h lamprey scars during the spring and e a r l y summer. Recruitment from the sea has been cut o f f by the impoundment and a landlocked race i s l e f t to continue the c y c l e . The s i z e of the scars i n d i c a t e a dwarfed race of lamprey or immature s i z e lengtk A s i m i l a r dwarf lamprey occurs i n an impoundment i n C a l i f o r n i a (Coots 1955). The greater length of migrating anadromous P a c i f i c lamprey that ascend H e l l ' s Gate on the Fraser, Moricetown F a l l s on the B u l k l e y , and Bridge River Rapids and Stamp F a l l s on Vancouver Island seem t o agree with Lack (1954) who states that greater length and fecundity i s associated with longer migratory journey. Five specimens obtained from N i l e Creek, a short, small stream, have a mean s i z e of 217 mm. The reduction i n s i z e and f e c u n d i t y of the landlocked lampreys of the Great Lakes gives added support t o t h i s theory. The length of the adult Entosphenus of the N i c o l a Thompson system was not determined. Recently  transformed  a d u l t s of mean length 122 mm. were c o l l e c t e d during December 1961 and A p r i l 1962.  One specimen 300 mm. long c o l l e c t e d i n •  December 1961 represented the w i n t e r i n g migratory year c l a s s which would spawn the f o l l o w i n g s p r i n g . Large adult s i z e of lampreys i s suspected from the greater length of the ammocoetes c o l l e c t e d and from the p h y s i c a l and chemical p r o p e r t i e s of the N i c o l a River system. 3• P a r a s i t i c L i f e of Entosphenus t r i d e n t a t u s Recently transformed  Entosphenus feeds  parasitically  soon a f t e r transformation and migration to the sea or l a k e . Small P a c i f i c Lampreys were c o l l e c t e d i n June attached t o  37  Table 2. Incidence of lamprey scars on trout i n E l s i e Lake. D.R. Hurn, 1 9 6 3 , B r i t i s h Columbia F i s h and Game Branch. •  Date  No. of f i s h sampled  Percent o l d & new scars  1  Percent Percent old scars > new scars  20 May  59  47  76.63  6 May  60  80  57.5  27.5  30.0  6 June 60  24  66.67  29.17  37.5  13 J u l y 62  110  40.91  13.64  27.27  19  52.63  21.05  31.58  117  15.20  8.77  6.43  3 A p r i l 63 5 June 63  F i g . 21  2.13  74.5  Lamprey scar on the opercule of a 6 l b . pink salmon caught near Sooke August 2 1 .  3$  shore feeding and spawning h e r r i n g i n Howe Sound. Predation i s common on salmon i n the Gulf of Georgia and the S t r a i t of Juan de Fuca during June t o September ( F i g 21). Numerous reports of lamprey attached t o h e r r i n g b a i t t r o l l e d from a l i n e have been reported from the same area at t h i s time. Landlocked  P a c i f i c Lamprey migrate t o the lakes where they  begin to feed on the resident t r o u t population. Hurn (personal communication) i n d i c a t e d a high incidence of p a r a s i t i s m (15-76 %) from a n a l y s i s of t r o u t bearing scars i n E l s i e Lake during the March t o J u l y period. In Cowichan Lake the period of greatest predation on t r o u t extended from January t o June ( F i g . 23 and Table 2 ) . Wigley (1959) reported that Sea Lamprey o f Cayuga Lake, New York, reached a peak of p a r a s i t i s m during August and September w i t h an incidence of 66 t o 70 % of the t r o u t bearing wounds. He found the greatest number of lamprey scars on the l a r g e s t t r o u t , but found no preference by lampreys f o r t r o u t of a c e r t a i n s i z e . A n a l y s i s of covariance revealed that the lake t r o u t with the greatest number of lamprey wounds are the t h i n n e s t , and smaller t r o u t suffered"more severeweight l o s s than d i d l a r g e t r o u t . Lampreys l o c a t e prey by vigorous swimming and o r i e n t a t i o n toward a chemical stimulus released i n t o the water from the prey (Kleerkoper 195$) • > The chemical stimulus i s perceived by the o l f a c t o r y organ l o c a t e d i n the lamprey's s i n g l e n o s t r i l . The f i n a l l o c a t i o n of the prey i s  accomplished  by an e l e c t r i c f i e l d that surrounds the head region of the lamprey (Kleerkoper 1958). This e l e c t r i c f i e l d (200-300 _u> v o l t )  39  F i g . 22  Rainbow t r o u t (Salmo g a i r d n e r i i ) g i l l netted i n E l s i e Lake showing lamprey scar marks. A- pointers i n d i c a t e o l d scars. B- f r e s h scar.  F i g . 23  V e n t r a l view of i n t e s t i n e (pin i n s e r t i o n ) of adult Entosphenus. A- Spawning male, N i l e Creek, June, complete atrophy. B- Female one year p r i o r t o spawning, Cowichan Lake, January, feeding reduced, atrophy s t a r t e d . C- Male, Cowichan Lake, January, a c t i v e l y feeding.  comes Into use 5-10  40 cm. from the prey and enables the lamprey  to make f i n a l attachment to the prey. Suction and the horny teeth enable the buccal d i s c to be f i r m l y attached. A hole i s rasped through the s k i n and i n t o the f l e s h by a toothed tongue and the blood and body j u i c e s are extracted by s u c t i o n . A powerful anticoagulent i s i n j e c t e d that keeps the blood f l o w i n g , helps to corrode the f l e s h , and thus enlarges the wound (Kennedy 1956). Duration of Attachment C a r l (1953) reported that a c t i v e l y feeding Entosphenus 200 mm.  i n length from Cowichan Lake kept i n a  tank attached to cutthroat t r o u t , brown t r o u t , char and coho salmon f o r a period of one day to s e v e r a l weeks. Kennedy (1956) reported that Sea Lamprey i n the Great Lakes remained • attached to prey f o r at l e a s t one day to a week. Hurn (personal communication) found that Entosphenus i n E l s i e Lake attached most f r e q u e n t l y below the l a t e r a l l i n e and p o s t e r i o r to the opercule ( F i g . 22). Wigley (1959) analysed lamprey scars and found 49% i n the p e c t o r a l , 25% i n the p r e p e l v i c , 23% i n the p e l v i c , and 5% i n the head region. Wigley found few scars above the l a t e r a l l i n e of the prey. This seems to i n d i c a t e that the lamprey attacks the f i s h from behind  and  below i n the region very near the heart. No dead or dying f i s h have been reported from lakes or the sea as a r e s u l t of lamprey attacks i n B r i t i s h Columbia. However, i t i s evident that the s u r v i v i n g and attacked f i s h are s e r i o u s l y weakened. Kennedy (1956) found that Sea Lamprey i n aquaria k i l l e d t h e i r prey i n most cases.  41 4. Sex Ratio and Length of Spawners I' Lampetra The o v e r a l l sex r a t i o f o r the Salmon River proved to be n e a r l y even 1.2:1 f o r 1960-1963 (Males/females see F i g . 24). Schultz (1.930). recorded the sex r a t i o at 2-32:1 f o r the same'species i n Washington. The sex r a t i o i n the upstream and downstream samples i s s i g n i f i c a n t l y d i f f e r e n t , as there i s a l a r g e r proportion o f females downstream, 1:2, and a l a r g e r proportion of males upstream, 2.5:1 ( F i g . 24^). There i s a l s o a s i g n i f i c a n t d i f f e r e n c e i n lengths between males (mean 113-4) and females (mean 126.8  t=  3-1  p =J>.0l) f o r the adults c o l l e c t e d during the spawning season ( F i g . 2 4 A ) . Schultz (1930) found the opposite r e l a t i o n s h i p , the males were l a r g e r than the females (means of 112 and 107.8 r e s p e c t i v e l y ) . The e f f e c t s of sex and stream l o c a t i o n are confounded on the Salmon R i v e r . The  upstream  i n d i v i d u a l s of both sexes are smaller and males preponderate, while downstream the animals of both sexes are l a r g e r and females are the more abundant sex ( F i g . 24B, 24C, and 24D). Hardisty (1961) found no s i g n i f i c a n t d i f f e r e n c e between the length of the sexes f o r L. p l a n e r i i n England over a ten year period. These sex r a t i o s and d i f f e r e n c e s i n s i z e o f f e r some food f o r s p e c u l a t i o n . The l a r g e s i z e of the a d u l t s downstream suggests that there i s a g r e a t e r growth due t o a b e t t e r food source. Since the stream increases i t s flow downstream and the gradient decreases, more diatoms and other algae w i l l be a v a i l a b l e to the l a r v a e . The greater number of females i n the  42  5 X = 126.8  DOWNSTREAM  i  14 0  120  100  S E X RATIO 1.3:1  O  O  r  UPSTREAM  0* 7=113.6  ID.  100  110  120  LENGTH FIG. 2 4 A . L E N G T H  130  140  100  IN MM  120  140  LENGTH  DISTRIBUTION  OF  FIG. 2 4 B .  ADULTS.  LENGTH  160  IN MM DISTRIBUTION  OF  SEXES.  •  1961-62 1963  a  DOWNSTREAM in.  DOWNSTREAM S E X RATIO U2  in  CN-  o  Ji  ,_• 110  P I , 120  • 130  l  rJOL  140  O  120  14 0  O  -z. m  100  150  z  UPSTREAM  IJJL 100  110  120  130  K0  100  L E N G T H IN MM FIG. 24 C . L E N G T H MALES FIG. 2 4 .  RIVER , 1961 — 6 3 .  120  LENGTH  DISTRIBUTION  LENGTH-FREQUENCY  SALMON  UPSTREAM S E X RATIO- 2.5:  in.  OF  F I G . 2 4 D . LENGTH FEMALES.  DISTRIBUTION  OF  ADULT  140  IN MM DISTRIBUTION  L. P L A N E R I  IN  OF  THE  43 downstream c o l l e c t i o n suggests a greater reproductive p o t e n t i a l f o r the downstream population. This trend occurred i n three separate years so i t does not i n d i c a t e sampling  variability.  Thus the downstream population would have a d e f i n i t e advantage i n a greater number of eggs and a greater number of females. Observations  on a d u l t s held i n aquaria at d i f f e r e n t  temperatures o f f e r some explanation f o r the sex r a t i o . At low temperature (<O-0°C) the females are the aggressive  nest  b u i l d e r s and are a c t i v e on the g r a v e l , while the males are u s u a l l y a c t i v e f o r short periods only. Males spend most of the time hidden under rocks near the spawning area. Thus a greater proportion of the females would be sampled during the e a r l y part of the season when the temperature i s c o l d . When spawning lampreys are t r a n s f e r r e d from a cold tank (3-10°G) to a warm tank (14-16°C) the behaviour changes. The male becomes the aggressive nest b u i l d e r while the female spends more time away from the nest h i d i n g under stones. C a r e f u l temperature a n a l y s i s i n the stream c o r r e l a t e d with sex r a t i o throughout the season and at various times of the day should prove rewarding. was  There  a two degree higher temperature i n the upper part of the  stream i n 1963, which would i n d i c a t e a higher proportion of males and an e a r l i e r spawning i n the upper reaches. However, spawning adults were f i r s t discovered downstream i n 1961 1962.  Upon more c a r e f u l sampling during 1963  and  the upstream  population was recorded spawning just as e a r l y , or e a r l i e r . Dead adults upstream and spawned out females i n d i c a t e that the upstream population may  have s t a r t e d to spawn e a r l i e r than the  downstream population. I f a spawning migration takes place i n  44 the  lower reaches of the r i v e r i t seems reasonable that the  females are more a c t i v e i n cold temperatures than the males and would thus move to the upper gravel areas of the downstream area ( s t a t i o n l ) before the males. Thus they would appear on the  nest f i r s t and i n greater proportion than the males. As  the  season progresses and the temperature r i s e s there would  seem to be an increase i n the number of males, as i s the case. However, aquarium holdings of spawning a d u l t s (S-14 C) G  i n d i c a t e that the males l i v e d f o r at l e a s t s i x weeks a f t e r spawning s t a r t e d while a l l the females died w i t h i n four weeks of c o l l e c t i o n . However, when adults are kept at higher temperatures (16-20°C) females s t i l l d i e f i r s t but males u s u a l l y d i e w i t h i n two weeks of c o l l e c t i o n . Therefore, behaviour of a d u l t s at d i f f e r e n t temperatures and l o P g i v i t y of each sex a f t e r spawning may e f f e c t the sex r a t i o of collections. Hardisty (1954) analysed L., p l a n e r i sex r a t i o i n many streams i n England over more than ten years and reported great v a r i a t i o n i n d i f f e r e n t streams from year to year. Zanandrea  (1961) and Hardisty (I96l) found that the sex r a t i o  upon reaching the adult stage was even but as the season progressed the number of males always outnumbered the number of females. Applegate (1950) and Surface (1897) found s i m i l a r conditions f o r Petromyzon  marinus.  Greater l o n g i v i t y of males was suspected by the above workers as a p o s s i b l e explanation f o r the greater number of males as the season progresses. Hardisty (1954) made weekly a n a l y s i s of sex r a t i o throughout the season and found that  45  .  the s m a l l e s t p r o p o r t i o n of males was  found i n the l a s t week  of the spawning season. H a r d i s t y (1961) found a d i s t i n c t correlation The  between the sex r a t i o and the r e l a t i v e  y e a r s , w i t h the lower r e l a t i v e  w i t h a sex r a t i o of 1.8  abundance.  abundance were a s s o c i a t e d  or l e s s while r a t i o s  higher than  2.2  were a s s o c i a t e d w i t h g r e a t e r numbers of a d u l t s . S i m i l a r c o r r e l a t i o n s were r e p o r t e d by A p p l e g a t e ( 1 9 5 0 a , 1950b) f o r . P. marinus. W i g l e y (1959) found t h a t when sea lampreys were abundant t h e r e was  a h i g h e r p r o p o r t i o n of males ( 3 2 ) and i n ;  y e a r s o f low abundance the r a t i o was  n e a r l y 1:1. H a r d i s t y (1954)  suggests t h a t t h e d i f f e r e n c e i n sex r a t i o may environmental  be caused  by  c o n d i t i o n s as t e m p e r a t u r e and n u t r i t i o n  ~~  i n f l u e n c i n g the ammocoetes. Because of the l o n g ammocoete l i f e he c o n s i d e r e d the t r a n s f o r m a t i o n year as b e i n g c r i t i c a l the e n v i r o n m e n t a l  effect  on the sex  to  ratio.  Entosphenus S m a l l sample s i z e of the adult's prevents  drawing  r e l i a b l e c o n c l u s i o n s about the p o p u l a t i o n . From the 11 a d u l t s collected,  the sex r a t i o i s 1:1.8  which i n d i c a t e s a s m a l l  p o p u l a t i o n s i z e a c c o r d i n g t o H a r d i s t y s t h e o r y . A sample of T  12 m i g r a t i n g a d u l t s on the Stamp R i v e r r e v e a l e d a 1:1  relation.  5• F e c u n d i t y o f B r i t i s h Columbia Lampreys The number of eggs i n a one  gram or l e s s  the ovary were counted and weighed ( b l o t t e d remainder of the ovary was eggs o b t a i n e d  s e c t i o n of  d r y ) . Then the  weighed and the t o t a l number of  by s i m p l e c a l c u l a t i o n  (Vladykov  1955).  46 Lampetra A l a c k of mature but unspawned females from the Salmon R i v e r makes e s t i m a t i o n of f e c u n d i t y d i f f i c u l t f o r t h i s p o p u l a t i o n . Only two  distended  were f o u n d . These c o n t a i n e d  or n e a r l y unspawned females  1136  and 1900  eggs. However,  samples from C u l t u s Lake ( S w e l t z e r Creek f e n c e ) produced estimates  of f e c u n d i t y between 2300 and  Hooknose Creek p o p u l a t i o n had  a s l i g h t l y higher  w i t h a mean of 2900 f o r the two H a r d i s t y ( I 9 6 0 , 1963) production  and  3000 w h i l e  populations  fecundity  (see Table 3 ) .  Zanandrea (1961) r e c o r d e d  at 1000-2000 (mean 1500)  the.  egg  f o r L. p l a n e r i i n  Europe. Zanandrea found a s l i g h t l y h i g h e r number of eggs (mean 1$50)  f o r L. zanandrea of T r e v i s o , ' I t a l y . E x a m i n a t i o n  of spawned out dead a d u l t s from t h e Salmon R i v e r r e v e a l s v e r y few  eggs l e f t i n the body Hardisty  (1-7).  (196ljl9°3) suggests reduced f e c u n d i t y i n  dwarf f o r m s ' i s c o u n t e r b a l a n c e d  by a reduced m o r t a l i t y . In h i s  I960 paper he uses oocyte number i n ammocoetes as a means of s e p a r a t i n g L. p l a n e r i from L. f l u v i a t i l u s . He suggests t h a t t h e brook lamprey evolved i t s s i z e and  from the r i v e r lamprey by  reducing  egg number but t h i s i s b a l a n c e d by a reduced  m o r t a l i t y a s s o c i a t e d w i t h abandonment of anadromous m i g r a t i o n . Hardisty estimated  the oocyte number of L. p l a n e r i ammocoetes  a t 5000-10,000; d u r i n g metamorphosis the g r e a t e r p a r t of  the  ovary a t r i f i e s as o n l y 1000-2000 eggs are l a i d . Svardson  (1949)  has  suggested t h a t reduced f e c u n d i t y i n f i s h e s i s accompanied  by an i n c r e a s e i n egg  s i z e , but t h i s does not o c c u r i n lampreys  47 ( H a r d i s t y 1963)• H a r d i s t y a l s o suggests t h a t p r e c o c i o u s  sexual  m a t u r i t y w i t h reduced p o t e n t i a l f e c u n d i t y occurs i n p a i r e d r e s i d u a l and andromous lampreys. Rensch (1959) r e p o r t e d t h a t i n f i s h and  reptiles  i n c r e a s e d body s i z e r e s u l t s i n g r e a t e r egg number r a t h e r than l a r g e r eggs. However, Lack (1954) suggested t h a t the e x t e n t  of  the spawning journey t h a t the female undertakes and the number of primary The  o o c y t e s present  large.lampreys  i n t h e o v a r i e s determines f e c u n d i t y .  w i t h t h e g r e a t e s t number o f eggs c o u l d  c o n c e i v a b l y r e p r e s e n t t h e i n d i v i d u a l s t h a t migrate  the  greatest  d i s t a n c e , thus compensating f o r the g r e a t e r m o r t a l i t y w i t h i n c r e a s e d egg number. Egg  s i z e of Lampetra i s not v e r y v a r i a b l e i n the  Salmon R i v e r . The  G u l t u s Lake specimen was  t a k e n i n the  S w e l t z e r Creek fence so complete m a t u r i t y of the eggs cannot be d e t e r m i n e d , but the eggs were not c o m p l e t e l y o v a r i e s which i n d i c a t e s  f r e e from the  immaturity.  Entosphenus No mature unspawned Entosphenus were c o l l e c t e d from the Salmon R i v e r but from s i z e a l o n e a h i g h p o t e n t i a l e x i s t s i n p a r t of t h e p o p u l a t i o n . A n a l y s e s  of unspawned Stamp R i v e r  and Hooknose Creek p o p u l a t i o n s r e v e a l an average f e c u n d i t y of 34,000 eggs w i t h the h i g h e s t number b e i n g 106,000 eggs i n the l a r g e s t i n d i v i d u a l examined. The  sample s i z e i s not  sufficient-  l y l a r g e t o w a r r a n t a r e g r e s s i o n a n a l y s i s . Applegate found t h a t the number of eggs produced i n c r e a s e d q u i t e r a p i d l y w i t h i n c r e a s e i n t o t a l l e n g t h , but t h a t i n c r e a s e d weight was  more  48  d i r e c t l y p r o p o r t i o n a l t o egg p r o d u c t i o n . W i g l e y (1959) r e p o r t e d a l i n e a r r e l a t i o n between body l e n g t h and egg number f o r Cayuga Sea Lamprey. H a r d i s t y r e p o r t e d a r e d u c t i o n i n egg number i n l a n d l o c k e d Sea Lamprey  (mean 6 2 , 0 0 0 , V l a d y k o v 1951)  from t h e p a r e n t Sea Lamprey t h a t l e d an adromous l i f e  (mean  171,000 eggs, V l a d y k o v 1 9 5 1 ) • B e t t e r c o l l e c t i o n s o f unspawned' Entosphenus o f t h e s m a l l e r s i z e g r o u p i n g s from t h e Salmon and Cowichan R i v e r s may r e v e a l from f e c u n d i t y d a t a a p a r a l l e l t o l a n d l o c k e d and e s t u a r i n e r a c e s of P a c i f i c Sea  Lamprey.  The number o f unspawned eggs i n dead spawned out specimens o f Entosphenus from t h e Salmon R i v e r were 3 5-13 5 eggs. A p p l e g a t e (1950) r e p o r t e d a 5% r e t e n t i o n of eggs a t d e a t h . He n o t i c e d an i n c r e a s e i n t h e r e l a t i v e p e r c e n t a g e of unspawned eggs i n f e m a l e s a t t h e v e r y end of t h e season i n Lake Huron Sea Lamprey. Thus a g r e a t e r r e p r o d u c t i v e  potential  e x i s t s f o r eggs t h a t a r e produced by females a t the b e g i n n i n g o f t h e season. The egg d i a m e t e r of Entosphenus i s v e r y s i m i l a r t o Lampetra ( T a b l e 3-) • The eggs of b o t h s p e c i e s a r e e l i p t i c a l i n shape; immature m i g r a t i n g Entosphenus p o s s e s s i n g eggs t h a t a r e one h a l f t h e s i z e o f mature eggs. Ten eggs o f Entosphenus were c r o s s - f e r t i l i z e d w i t h Lampetra and development proceeded t o n e u r u l a but development stopped a t t h i s s t a g e . T h i s s u g g e s t s t h a t h y b r i d i z a t i o n may be p o s s i b l e . From aquarium o b s e r v a t i o n s , male Lampetra were seen spawning w i t h female Entosphenus when no Entosphenus male was a v a i l a b l e . Male Lampetra a l s o t o o k t h e spawning p o s t u r e on male Entosphenus. However, Entosphenus u s u a l l y p r e f e r l a r g e r g r a v e l s i z e a r e a s and deeper w a t e r f o r  49 • Table 3. Fecundity and Egg; Size of B r i t i s h Columbia Lampreys Unspawned Entosphenus t r i d e n t a t u s Location  Date June 20, 1961  Stamp River It it  IT Tt  it tt  tt  t t  tt  tt  tt  Tt  tt  it tt  tt  Hooknose Creek tt  Tt  tt  May  1959  tt  Mean  Length  No. Eggs  325  18,600 10,100 30,500  310  308 375 311 406  35,400  262  15,500 106,100 24,800  175 170 196 166 171 156 153 127 111 118  3,700 3,300 3,700 2,900 1,700 3 ,000 2,900 2,300 1,100 1,900  194 204  35 135  100  4 7 6 8 2 1  34,400  Unspawned Lampetra p l a n e r i Hooknose Creek  Feb.  1957 Tf  tt  tf  it  tt  it  TT  tf  Tf  tt  tt  tt  tt  Tt  Sweltzer Creek tt  tt  Tt  Tt  Salmon River  tt  TT  May 30, . 1942 tt  It  Tf  Tf  tt  Tf  May 27, Tf  Tt  1962 Tf  Mean Eggs remaining i n spawned out females Entosphenus . Salmon River Tt  June 2, 1962  Tt  Lampetra Salmon River tt  Tf Tf tt Tf  May 2 7 , tf  Tt  Tf  tf  1962 it  tt  1962 May 6, A p rTf i l T20,1962 f  96  110 105  130  135  Table 3 continued and completed on next page.  50 Table 3 Fecundity and Egg Size of B r i t i s h Columbia Lampreys Egg Size (ocular micrometer measurement of 10 eggs from each adult) Lampetra Location Salmon River tr  tr  Smith Creek  Date  Length  Width mm.  Length mm.  June 3, 1962 May 27, 1962 June 9, 1961  110 111  138  1.07 1.09 .98  May 1959 May 31, 1962 June 4, 1962 June 20,1962  406 214 193 204  1.09' 1.09 1.06 1.09  1.24 1.14 1.12 1.17  June 20,1961  375  .57  .69  . •  1.12  ' 1.13 1.05  Entosphenus Hooknose Creek Salmon River Tt  t!  tf . tf  Stamp River immature  51 nest b u i l d i n g while Lampetra w i l l occupy an area downstream from that preferred by Entosphenus. The difference i n s i z e seems to offer no obstacle as f e r t i l i z a t i o n takes place i n the water and sperms remain v i a b l e f o r some time as i n d i c a t e d from a r t i f i c i a l f e r t i l i z a t i o n of Sea Lamprey, P i a v i s (I960), Lennon (1955). 6. Spawning of Lampreys •.(a) Methods of A n a l y s i s Observations of lampreys spawning under n a t u r a l conditions were made i n 1961 and 1962 at weekly i n t e r v a l s when the stream was not f l o o d i n g . Occasional observations were made during 1963. Surface current was measured over the nest using a cork attached to a 10 foot length of nylon l i n e . Laboratory observations of lampreys were made during the same p e r i o d . S t i l l water aquarium observations were undertaken i n 1961 and 1962 when 7 g a l l o n standard s t a i n l e s s . s t e e l aquaria were f i l l e d with 8 inches of water above a 3 inch l a y e r of g r a v e l which was obtained from lamprey spawning beds. Two. a i r stones i n each tank kept the water c i r c u l a t i n g and the tanks were placed i n the e a s t - f a c i n g window of a basement during the f i r s t two years and under flourescent l i g h t i n g near the laboratory windows during the l a s t year. The temperature i n these s t i l l water tanks ranged from 15°C to 20°C. When the temperature of the tanks .in the basement window rose i n .the . e a r l y summer they were removed from the window l o c a t i o n to a t a b l e f o u r . f e e t from the window to prevent excessive heating. . .• Running water tanks were e s t a b l i s h e d i n 1963 using  52  dechlorinated water flowing through a large 60 inches by 20 inches by 30 inches tank with 5 cm. of bottom type and 20 cc. of water above t h a t . The tank had glass s i d e s , wooden ends, and a metal bottom ( F i g . 25). A continuous current was maintained i n the tank (.2 t o -35 f e e t per second) and with a flow of 300 to 400 cc. per second ( F i g . 2 6 ) . A temperature of 8 to 10°G was maintained throughout the spawning season. During A p r i l the temperature was 8°C, during June i t was 10°C. One t h i r d of the bottom was covered with sand, the remainder of the tank was covered w i t h g r a v e l taken from the Salmon R i v e r . Current speed was tested with a Leopold Stevens current meter. The second running water tank was constructed of white f i b e r glass over plywood with one glass side and a glass top.  A small i n f l o w of water (5-7 cm. per sec.) was maintained o 0  i n order t o keep the temperature between 11 C and 14 C  The  water depth was 8 inches and 3 inches of spawning gravel covered the bottom. Motion p i c t u r e s were taken of the 1963 spawning, i n order to analyse behaviour; 35 mm. photographs were taken throughout the time to analyse the p o s i t i o n s and a c t i o n s of the lampreys. During the 1962 spawning season one of the wooden tanks 60 inches by 30 inches was darkened with black p l a s t i c on a l l sides which allowed only d i f f u s e d and r e f l e c t e d  light  to s t r i k e the bottom of one side of the aquarium. The a i r stones kept the water c i r c u l a t i n g  so that there was no  temperature d i f f e r e n c e between the two sides of the aquarium.  53  F i g . 25 Experimental spawning tanks. A (16-20°G.)contains s t i l l aerated water; B (11-15°C) and C (8-10°C.) contain c i r c u l a t i n g water.  Top view of a spawning tank (C) showing current v e l o c i t y i n feet per second. A - water i n l e t ; 0 - water, o u t l e t .  .35 .3 .25 GRAVEL  _L  SAND  Side view of spawning tank (C). Figure 26 Spawning tank (C above) (8-10 C ) showing current and bottom arrangement.  54 Another tank 20 inches by 40 inches had an aluminum p a r t i t i o n separating-the  two halves of the aquarium, and g r a v e l  from the n a t u r a l spawning bed was placed i n the bottom of one . and sand i n the other. stones.)  (Later the sand was replaced by f i n e  Observations of bottom preference f o r nest b u i l d i n g  were made. An experimental trough was a l s o placed i n the stream with one h a l f of i t covered with a black p l a s t i c sheet' while the other end was kept i n the s u n l i g h t on a r i f f l e area with a current flow s i m i l a r to that of the a c t u a l spawning r i f f l e s . (b) Spawning Requirements of Lampetra M a t u r i t y of Sex Products The prime requirement for spawning a c t i v i t y i s the presence of mature reproductive products. Evidence f o r t h i s conclusion i s shown i n the f o l l o w i n g two examples. On A p r i l 29, 1963, an immature Lampetra from the Salmon River was introduced i n t o a 16-20°C. tank c o n t a i n i n g g r a v e l . The animal immediately burrowed i n t o the g r a v e l and remained concealed u n t i l i t reached maturity on June 2. During t h i s time other mature L . p l a n e r i used the tank for spawning but the immature specimen remained beneath the g r a v e l . The specimen appeared to be a male when f i r s t introduced i n t o the tank, but a f t e r three weeks i t s abdomen began to s w e l l and d i s t e n d , and the pseudoanal f i n began to enlarge. On June 2,the animal l e f t the gravel and began to swim a c t i v e l y around the tank and at the surface of the water. Mature eggs' could be seen c l e a r l y through the transparent  and distended abdomen.  55  Two male Lampetra were c o l l e c t e d from the f i s h fence at Sweltzer Creek on A p r i l 4, 1963, and placed i n an 8-10°C the  tank f o r observation. They remained burrowed under  rocks f o r the f i r s t three weeks but i n the f o u r t h week  they made exploratory swimming excursions around the tank and began to l i f t rocks and d i g p e r i o d i c a l l y . They became more a c t i v e and spawned with females that were introduced i n t o the  tank. One died on June 4, and the other was k i l l e d  May 27 as the v i a b l e sperm was used t o f e r t i l i z e  on  eggs.  Spawning temperature and gravel were present i n each of the above instances but the animals d i d not mature and move from the g r a v e l u n t i l t h e i r sex products and secondary  sex c h a r a c t e r i s t i c s were mature. In the Salmon R i v e r , the  d i f f e r e n c e s i n maturity date between i n d i v i d u a l s accounts f o r . the  long spawning period- from A p r i l to J u l y .  Temperature  Effects  Brook lamprey of the Salmon River were observed spawning and l a y i n g eggs under l a b o r a t o r y and f i e l d conditions w i t h i n the temperature range of 8-20°C . Hardisty (I96l) states that temperatures of 10-11°C  are. c r i t i c a l to appearance  of spawning a c t i v i t y i n Lampetra p l a n e r i i n the r i v e r l e o . He recorded i s o l a t e d animals on the spawning s i t e at temperatures below 10°C. the  A marked r i s e i n numbers of animals occurred as  temperature rose above 10-11°C  and showed a high degree  of c o r r e l a t i o n with temperature. This behaviour was v e r i f i e d i n l a b o r a t o r y observations on Salmon River lampreys i n a cold tank (8°C  ) where most animals h i d beneath the g r a v e l ,  but when the temperature rose above 10°C.  a l l the animals  56  l e f t the g r a v e l . In 1961 the f i r s t adults were seen i n May. However, the  temperature was above 10°C, f o r some time before t h i s  ( i n d i c a t e d by F i g . 6 ) therefore f i r s t spawning could have occurred during the l a s t two weeks i n A p r i l . In 1962 the f i r s t s i g n of spawning was observed on A p r i l 20, at a temperature of 9°G. •. High i n t e n s i t y  spawning  i n a number of communal nests was observed. The temperature, and flow data which i n d i c a t e s f l o o d i n g c l e a r l y shows that spawning probably s t a r t e d near the 1 0 t h of A p r i l .  (Fig.7).  This was v e r i f i e d by examination of some of the females that were i n a spawned out c o n d i t i o n . By analysing flow and temperature data f o r 1961 and 1962 i t i s p o s s i b l e to conclude that spawning could s t a r t i n the Salmon River as e a r l y as the  1 0 t h of A p r i l and extend u n t i l the f i r s t week i n J u l y . In 1963 the r i v e r was checked i n l a t e March and  oh A p r i l 7, but the temperature was low and no a d u l t s were obtained w i t h s e i n i n g or on the gravel areas. Spawners were f i r s t seen on A p r i l 20 when the temperature was 11°C. at s t a t i o n 1, and 11.5°C. at s t a t i o n s 4 and 6. When these spawners were d i s s e c t e d i t was found that some were spawned out, ~ e s p e c i a l l y the upstream i n d i v i d u a l s . In general i t appears that' i n the Salmon River spawning commenced i n m i d - A p r i l . Schultz (1930) found L. p l a n e r i spawning i n Washington State streams during a s i m i l a r time to that reported for  B r i t i s h Columbia. C a r l ( 1 9 5 3 ) reported Lampetra  spawning  i n Holmes Creek i n May. The Sea Lamprey prefers a much higher  57 temperature ( 1 8 - 2 l ° C , ) f o r i n i t i a t i o n of spawning (Applegate 1950,  Scott 1957, and Wigley 1959). The above workers found,  that i f the temperature dropped below 18°C. the Sea Lamprey stopped spawning'. This does not occur i n Lampetra of the Salmon River f o r as temperature dropped the spawning d i d not stop, but spawning behaviour i s d e f i n i t e l y affected by temperature as w i l l be discussed i n d e t a i l l a t e r . • Flooding Flooding l i m i t s spawning after the temperature r i s e s above 10°C. because the increased current prevents the adults . from occupying a p o s i t i o n on the g r a v e l . . Seining over the gravel areas during f l o o d i n g d i d not produce any adults although adults were common on the same s t r e t c h of gravel two days before f l o o d i n g occurred. Temperature and f l o o d i n g c o n d i t i o n s i n 1962 i n d i c a t e that spawners should appear on the gravel during the second week i n A p r i l . Current  Preference A l a r g e trough f i l l e d w i t h g r a v e l was placed i n a  r i f f l e area of the Salmon River where the current was 3 feet per second ( F i g . 27)• A board over the end screen c o n t r o l l e d the current i n the tank. A current of 1 f t .  sec. was maintained  and 8 adults were introduced i n t o the rear of the trough. The p o s i t i o n of the adults was observed a f t e r one hour. Then the current was increased to 2 f t .  per sec. and the p o s i t i o n of  the adults recorded again. The experiment was repeated with eight new adults introduced i n t o the front of the trough and the same procedure was- followed as i n the previous run. The  58  experiments were performed on A p r i l 27, 1962, with a water temperature of 11°C .  *  F i g . 27 Experimental trough t o t e s t response of a d u l t s to current A current i s a requirement f o r spawning i n the stream h a b i t a t . In the Salmon River spawning always occurred i n g r a v e l over which a current flowed. Lampetra constructs i t s nest above r i f f l e areas i n current from 1 to 1.6 f t . per sec. v e l o c i t y at the surface. Current seems to be r e l a t e d t o depth of water over the nest since 8-15 inches i s the range of water depth observed (See Table 4 ) • In n a t u r a l conditions current and correct depth of water are more e s s e n t i a l than l i g h t to spawning requirements. However, the presence or absence of a current d i d not a f f e c t spawning behaviour or f e r t i l i z a t i o n of eggs i n aerated aquarium water. Spawned eggs i n the gravel of the aquarium hatched without extra care or c o n s i d e r a t i o n i n 1962 and 1963. Kennedy (1957) and Scott (1956-57) have a l s o found that Sea Lamprey can spawn i n p e r f e c t l y s t i l l water  59 i f the correct temperature and substratum are present. They were able to obtain f e r t i l e eggs from such spawnings. Current seems of l i t t l e importance i n aquaria, but when a l a r g e spawning tank was  constructed i n 1963 with a small c i r c u l a t i n g  current the nests were always constructed i n g r a v e l under the greatest current flow. Therefore, although f e r t i l e eggs have been spawned^ i n s t i l l aquarium water, i n d i c a t i o n s are that lamprey seek gravel over which a current flows. Current seems to f u n c t i o n i n mixing the egg and sperm during the release of sex products, and i n i n s u r i n g a ready supply of oxygen f o r the eggs i n the g r a v e l . Shade Preference The trough  ( F i g . 28-1)  of the Salmon ^ i v e r on May adjusted to 1.5  was  10, 1962,  placed i n a r i f f l e and the current  area  was  f t . per s e c . A large black p l a s t i c sheet  was  placed over h a l f the trough and 9 adult lamprey were introduced  Fig.  23 Experimental trough i n the stream ( l ) and l a b o r a t o r y tank (2) to t e s t the preference of spawning a d u l t s for l i g h t . A- s u n l i t s e c t i o n ; B- shaded s e c t i o n .  60 i n t o the downstream end ( l i g h t ) of the tank. The p o s i t i o n of the a d u l t s was recorded a f t e r 2 hours (1200-1400 hr.) of exposure to the apparatus. The p l a s t i c sheet was then moved to the opposite end of the trough and the p o s i t i o n of the lampreys was recorded two hours l a t e r (1400-1600 n r . ) . One week l a t e r s i x adults were introduced to the upstream  half  of the trough (dark) and the above procedure was repeated. A 10 g a l l o n wooden aquarium  (glass 2 s i d e s , Fig.28-2)  was set up i n a basement window and h a l f of the aquarium  was  covered w i t h black p l a s t i c . Twelve spawning Lampetra were introduced to the tank and observations were made at 0700 and 1700 hours d a i l y . Light' Sunlight seems to have some i n f l u e n c e on the choice of nest s i t e . Spawning lampreys g e n e r a l l y seek shaded areas i n the g r a v e l f o r nest c o n s t r u c t i o n . However, many nest occupied by spawning adults were observed i n open r i f f l e s during b r i g h t s u n l i g h t ( F i g . 29). Therefore other f a c t o r s such as c u r r e n t , bottom composition, and water depth seem more important f a c t o r s than s u n l i g h t . Laboratory experiments showed s i g n i f i c a n t l y that lampreys p r e f e r r e d the shaded area of the tank i n d a y l i g h t . Less than one t h i r d of the 14 experimental animals were seen on the sunny side of the aquarium during the week study period,, and on 10 occasions no animals were observed on the sunny side of the aquarium. Hagelin and S t e f f n e r (195$) state that bottom  61  F i g . 29  A p a i r of a c t i v e l y spawning L . p l a n e r i i n the Salmon River i n bright s u n l i g h t . The p a i r i s occupying a crude nest constructed between the l a r g e r rocks.  F i g . 30  Lampetra spawning i n the shade of a l o g i n the Salmon River.  62 c o n d i t i o n s are more i m p o r t a n t than l i g h t , They performed s i m i l a r o b s e r v a t i o n s t o those above and found t h a t L. f l u v i a t i l u s p r e f e r r e d the shade as a s i t e f o r n e s t c o n s t r u c t i o n . In  the r i f f l e n e s t s of the Salmon R i v e r Lampetra are found i n  both shaded and s u n l i t  areas.  These o b s e r v a t i o n s l e d t o f u r t h e r stream and a t r o u g h experiment  observations  i n the stream where a l l spawning f a c t o r s  were p r e s e n t . Ten spawning Lampetra p r e f e r r e d the shaded p a r t of the t r o u g h when t h e y were a l l o w e d t o d i s t r i b u t e for  themselves  a two hour p e r i o d . The g r a v e l , c u r r e n t , and depth o f water  were i d e n t i c a l t o t h a t of n a t u r a l r i f f l e a r e a s . A b l a c k cover was  plastic  then- moved to the o p p o s i t e end of the t r o u g h . A l l but  one p a i r of the animals moved from the s u n l i t g r a v e l t o the shaded a r e a . T h i s p a i r which had s t a r t e d t o c o n s t r u c t a n e s t remained on the g r a v e l i n the open s u n l i g h t and c o n t i n u e d w i t h the n e s t c o n s t r u c t i o n . T h i s suggests  that nests t h a t are  o c c u p i e d i n the sun are p r o b a b l y c o n s t r u c t e d i n the n i g h t but the a n i m a l s . w i l l remain i n the n e s t or h i d i n g beneath t h e r o c k s i n the n e s t i n b r i g h t s u n l i g h t . Near s t a t i o n 1 where the g r a v e l was  s m a l l and produced l i t t l e shade of i t s own,  n e s t s were b u i l t u s u a l l y i n the shade. Upstream where the l a r g e g r a v e l produced more shade of i t s own,  n e s t s were common  •in open s u n l i g h t . On one o c c a s i o n s i x communally spawning a d u l t s were seen t a k i n g r e f u g e i n the shade of a l o g ( F i g 3 0 ) . H a r d i s t y (1944) found t h a t Lampetra showed a p r e f e r e n c e f o r spawning i n the shade and u s u a l l y b u i l t n e s t s under a b r i d g e . or i n a p o s i t i o n p a r t l y shaded by t r e e s or b u i l d i n g s . -  63  In b r i g h t s u n l i t nests, the animals are e a s i l y f r i g h t e n e d and w i l l swim extemely s w i f t l y at the surface of the water to hide downstream i n the r i f f l e s  or upstream i n  the pool area. Males show a greater awareness, of t h e i r surroundings than do females. The body of a female can be touched i n the nest without causing her to leave the nest, but males respond immediately to the same a c t i o n . The animals i n the shade are not as e a s i l y f r i g h t e n e d from the nest. Bottom Preference One h a l f of the compartments of the trough ( F i g . 27) were f i l l e d w i t h sand and the other compartments were f i l l e d with gravel.. S i x adults were introduced to the sand end of the tank and the animals were allowed to d i s t r i b u t e themselves f o r a one hour period. The p o s i t i o n of the bottom type was reversed and the same s i x adults were introduced to the gravel end of the trough, and t h e i r p o s i t i o n recorded a f t e r the one hour period. The temperature, when these experiments were performed, of the Salmon River was 12°C.  on A p r i l 25, 1962.  Half the bottom of a 5 g a l l o n aquarium was f i l l e d to a depth of 3 inches w i t h sand and the remainder  of the tank  was f i l l e d w i t h spawning gravel from the Salmon River. The tanks were placed i n an e a s t - f a c i n g basement window and two d i f f e r e n t groups of 6 adults used the tank f o r spawning at temperatures of 16 to 18°C  . Spawning a c t i v i t y i n the two parts  of the tank was recorded. Gravel seems to be an important i n g r e d i e n t of the habitat f o r spawning lampreys. Lamprey p a i r s never spawned i n the sand area of an experimental.tank. On  64  occasion s i n g l e i n d i v i d u a l s would hang onto the glass and dig v i o l e n t l y i n the sand. This i s probably a form of low i n t e n s i t y spawning behaviour s i m i l a r t o the spawning a c t . However, two females released eggs when kept i n a sandbottomed- aquarium. Hagelin'(1959) found that L. f l u v i a t i l u s i n aquarium conditions selected a mixture of sand and g r a v e l over other bottom types. Scott (1956-57) reported that Sea Lamprey i n v a r i a b l y choose a mixture of coarse sand, g r a v e l , and small rocks over other bottom types f o r a nest s i t e . Dendy and Scott (1953) found that no spawning occurred i n a bare aquarium but as soon as coarse sand, g r a v e l , and stones were placed i n the aquarium immediate stone moving and spawning •followed. Hagelin confirmed the same r e a c t i o n i n L. f l u v i a t i l u s . Applegate (1950) showed a c o r r e l a t i o n between amount of spawning g r a v e l present i n the stream and the number of spawning lamprey. L. p l a n e r i i n B r i t i s h Columbia displayed no signs of spawning when kept i n a bare aquarium. Entosphenus Entosphenus has s i m i l a r spawning requirements t o Lampetra. They appear t o be l e s s s e n s i t i v e to sunlight but n nest c o n s t r u c t i o n i s l i m i t e d t o a few s i t e s i n the stream. During the 1962 and 1963 spawning, the same nest l o c a t i o n s were used. (c) Sexual Dimorphism at M a t u r i t y Lampetra Recently transformed lampreys can not be separated s e x u a l l y on the basis of e x t e r i o r morphology. The two d o r s a l  65 f i n s are s e p a r a t e d  i n the t r a n s f o r m i n g a d u l t and grow  c o n t i n u a l l y together' as m a t u r i t y approaches (Vladykov 1955)• The  i n t e s t i n e reaches i t s maximum s t a t e of d e g e n e r a t i o n a t  the ohset of spawning. No f o o d i s consumed f o r at l e a s t one year or p o s s i b l y two years p r i o r t o spawning (Leach I94O). A f t e r spawning commences the d o r s a l f i n s , a r e a  surrounding  t h e u r o g e n i t a l opening, and the b u c c a l d i s c of both sexes may  become i n f i l t r a t e d w i t h b l o o d . These are some of the  g e n e r a l i d e n t i f y i n g c h a r a c t e r i s t i c s of a r r i v i n g at t h e a d u l t stage. Zanandrea (1961) r e c o r d e d neoteny i n I t a l i a n Brook Lamprey ammocoetes. T h i s c o n d i t i o n was  Similar  to sexual  dimorphism w i t h t h e growth of a p s e u d o f i n , t r a n s p a r e n c y  of the  body w a l l but the e r i d d s t y l e arid naso-pharynx remained i n the l a r v a l - form. T h i s c o n d i t i o n was  never r e c o r d e d  i n the Salmon  River population. No exact time o f s e x u a l m a t u r i t y o c c u r r e d i n the Salmon R i v e r p o p u l a t i o n , but the appearance of s e x u a l dimorphism and m a t u r i t y o c c u r r e d throughout t h e spawning season. H a g e l i n  (1959) found the p e r i o d between s e x u a l m a t u r i t y  arid the appearance o f s e x u a l dimorphism was  two weeks. He-  observed d e c r e a s e s i n s i z e d u r i n g and a f t e r t r a n s f o r m a t i o n , as w e l l as a c o n t i n u a l l o s s of weight as spawning  progressed.  Four a d u l t s o b t a i n e d w i t h an e l e c t r i c shocker May  of 1962 r e v e a l e d them t o be i n the e a r l y a d u l t  in  stage.  T h e i r o r a l hoods were reduced i n s i z e and no pseutioanal f i n or body s w e l l i n g was  observed on the female.  A f t e r a period  of from one t o two weeks i n t h e aquarium these  animals  66  matured, developed secondary sex c h a r a c t e r i s t i c s and began to show spawning behaviour. This was also observed on one female c o l l e c t e d i n e a r l y May i n 1963 yet i t remained burrowed i n a warm tank (16-20°C ) u n t i l the end of May when the eggs and other sex c h a r a c t e r i s t i c s were mature. A l l recent  research  i n d i c a t e s that a l l spawning p a r a s i t i c and n o n - p a r a s i t i c lampreys develop secondary sex c h a r a c t e r i s t i c s at sexual maturity. The o l d idea that some specimens show no sex d i f f e r e n t i a t i o n i s no longer correct when complete information of l i f e h i s t o r y i s a v a i l a b l e (Zanandrea 1961). There appears to be no d i f f e r e n c e i n c o l o u r a t i o n between the sexes. Two colour phases i n the Salmon River population, one y e l l o w i s h golden-brown, the other a greyblack phase on the d o r s a l surface, are not c h a r a c t e r i s t i c of e i t h e r sex. A l l spawning adults can be d i s t i n g u i s h e d from transforming larvae by the presence of yellow or brown pigment i n the f i n s (Zanandrea 1 9 6 l ) . Male C h a r a c t e r i s t i c s Twenty male L . p l a n e r i (mean length 110.2 mm.) twenty females (mean length 110.0 mm.)  and  were s e l e c t e d at  random from the Salmon River adult c o l l e c t i o n s f o r measurements and comparison of sexual c h a r a c t e r i s t i c s . The f o l l o w i n g external c h a r a c t e r i s t i c s are those that appear on a s e x u a l l y mature male (Figures 31 and 32). 1. A slender u r o g e n i t a l p a p i l l a i s present i n a l l males with a range i n s i z e from 5.6  to 0.15 mm.  However d i f f e r e n t degrees  of p r o t r u s i o n make exact measurement d i f f i c u l t . Hagelin and  Fig. 31  Lateral view of the urogenital papilla of a male L. planeri and the surrounding structures (Salmon River)  Fig. 33  Lateral view of the swellings present in the female (A, B, G) Salmon River specimen  68 S t e f f n e r (195$) r e p o r t e d t h e maximum l e n g t h i n t h e R i v e r Lamprey as 6 mm  ( F i g . 31).  2. The two d o r s a l f i n s of the male a r e s l i g h t l y h i g h e r t h a n f e m a l e s ( 1 s t . d o r s a l 3.8: 3.06, 2nd. d o r s a l 6.3: 6.03, to  males  f e m a l e s ) . The base of t h e second d o r s a l f i n i s not s w o l l e n  as i s t h e case of the female ( F i g . 3 2 ) . 3 . No s i g n i f i c a n t d i f f e r e n c e was observed between eye d i a m e t e r , yet  Vladykov found a l a r g e r eye d i a m e t e r i n European Lampetra  males. 4. The o r a l hood of males i s l a r g e r than t h a t of f e m a l e s ( x 5.73:5.13). 5.  S l i g h t o r l i t t l e h y p e r t r o p h y was noted around t h e vent as  d e s c r i b e d by H a g e l i n and S t e f f n e r (1958). 6. The t a i l o f t h e male bends downwards w h i l e t h a t o f t h e female bends upwards ( F i g . 3 4 ) .  Fig.  34 D i s p l a y s t h e upward bend o f t h e t a i l of f e m a l e s and the downward bend of t h e t a i l of males o f L. p l a n e r i from t h e Salmon R i v e r , (m - males, f = females)  69  7.  The trunk of the males are shorter than the females, while  the t a i l of the male i s longer than that of the  female.  Female C h a r a c t e r i s t i c s The f o l l o w i n g c h a r a c t e r i s t i c s appear on a s e x u a l l y mature female: 1.  A pseudoanal f i n appears p o s t e r i o r to the vent ( F i g . 33)  i n the mature female. This f i n may  become f i l l e d with blood  due to rupture of c a p i l l a r i e s during the digging of the nest. 2. The second d o r s a l f i n i s markedly swollen at the a n t e r i o r edge ( F i g . 32)..  The semitranslucent oedema often becomes  f i l l e d with blood as spawning progresses. The swollen f i n i s a l l e g e d to serve as a stop f o r the male's t a i l as i t c o i l s around the lower body of the female and thus d i r e c t s the sperms on the eggs during the spawning act (Hagelin and S t e f f n e r 1958). 3. The a n t e r i o r edge of the vent i s u s u a l l y swollen i n a s i m i l a r manner to the pseudoanal f i n . 4. The sucking d i s c i s s l i g h t l y smaller i n the female. 5. The trunk of the female i s longer than that of the male, while the t a i l i s u s u a l l y shorter. 6. The abdominal body w a l l becomes transparent  and.distended  so that i n d i v i d u a l eggs can be seen w i t h i n . However, spawned 1  out or n e a r l y spawned out females may have very slender bodies. 7.  The t a i l of the female i s u s u a l l y turned upwards and i s  p a r t i c u l a r l y n o t i c e a b l e i n the w e l l preserved specimens and l i v e animals. 8. The u r o g e n i t a l p a p i l l a of the female i s reduced i n s i z e  70  F i g . 35  V e n t r a l view of the u r o g e n i t a l opening of E. t r i d e n t a t u s showing the p a p i l l a (A) and the pseudoanal f i n (B). Salmon River specimen.  F i g . 36  L a t e r a l view of the s w e l l i n g of the female E. t r i d e n t a t u s at the p o s i t i o n s i n d i c a t e d by the arrows.  F i g . 37  L a t e r a l view (A) and v e n t r a l view (B) of the u r o g e n i t a l p a p i l l a of the male E. t r i d e n t a t u s , showing the absence of the v e n t r a l s w e l l i n g .  71 ( l e s s than 2 mm.) and i s u s u a l l y enclosed by a f o l d of swollen skin. Entosphenus Entosphenus possess the same major sexual dimorphic c h a r a c t e r i s t i c s found i n Lampetra (Figures 35, 36, and 37). The males are u s u a l l y a red brown colour while the females are a darker brown or grey colour. The female body w a l l never becomes transparent as i t does i n Lampetra. The u r o g e n i t a l p a p i l l a of the male i s much shorter i n length compared t o Lampetra. The body i s u s u a l l y very much distended i n the unspawned female ( F i g . 38A and 38C).  F i g . 38 Salmon River spawning a d u l t s . Lampetra (E) and Entosphenus (A, B, & D) were taken from a communal nest. The distended female (C) contains over 106,000 eggs (Hooknose Greek) The rocks (F) from a Lampetra nest. The rocks (G) from an Entosphenus~nest.  72 (d) Prespawning A c t i v i t y Lampetra Few specimens were c o l l e c t e d and observed during t h i s stage because lampreys burrow i n t o the gravel and thus • become d i f f i c u l t to c o l l e c t by conventional s e i n i n g and digging methods. Several attempts to c o l l e c t adults during the winter months when Lampetra should be i n the prespawning c o n d i t i o n produced no specimens. A portable e l e c t r i c shocker was used i n May, 1962 to c o l l e c t four adults that were burrowed i n t o the gravel above a r i f f l e area of the Salmon R i v e r . These specimens were not captured when the area was dug over and swept with a seine the day previous. Two males were c o l l e c t e d from' the f i s h fence at Sweltzer Creek i n 1963 i n e a r l y A p r i l . One female was c o l l e c t e d from the Salmon River i n e a r l y May, 1963, by digging and s e i n i n g at n i g h t . The e l e c t r i c shocker method seemed to be most productive i n obtaining specimens of adults i n the prespawning c o n d i t i o n during the winter and e a r l y spring. The animals appear to burrow i n t o gravel areas at the lower end of large pools during the prespawning period. They seem to be i n a c t i v e and are not seen unless disturbed. Lampreys appear to spend t h i s period i n dormancy while maturity develops. C o l l e c t e d specimens observed i n an aquarium burrowed beneath the g r a v e l and were not seen u n t i l they emerged i n spawning c o n d i t i o n w i t h sexual dimorphic c h a r a c t e r i s t i c s f u l l y developed. In the prespawning stage the males cannot be d i s t i n g u i s h e d from the females.  73 A s l i g h t migration i n the Salmon River i s suspected p r i o r to spawning, from the muddy lower reaches to above s t a t i o n 1. No spawning gravel i s a v a i l a b l e below s t a t i o n 1 and the f l o o d i n g conditions of the stream during the winter c a r r i e s ammocoetes to the lower s i l t e d regions of the stream. On A p r i l 20, 1962, and 1963, a migration of spawning adults was observed above s t a t i o n 1. One, mile above the s t a t i o n and at s t a t i o n 2 no a d u l t s were seen but spawning adults and adults moving upstream were captured on the gravel at s t a t i o n 1 ( F i g . 3 ) . P. Wickett (personal communication), c o l l e c t e d lampreys at the f i s h fence on N i l e Greek from 1948 t o 1954 and recorded movement of lampreys down the creek from A p r i l to J u l y with the peak movement occurring i n May and June. These f i g u r e s r e v e a l some movement during the prespawning period but the greatest movement w i t h i n the stream occurs with the onset of J.  • spawning. Leach (1940) observed l a b o r a t o r y - h e l d I . f o s s o r to be semi-sedentary u n t i l January when some specimens d i d not bury themselves while others were seldom out of the sand u n t i l A p r i l . Leach measured seven i n d i v i d u a l s kept i n a cool c e l l a r during the winter and found that they reduced t h e i r length by 10 percent during the prespawning period. These animals seemed t o lack the normal spawning stimulus t o spawn n a t u r a l l y , but the sex products proved v i a b l e when f e r t i l i z e d artificially. Schultz (1930) n o t i c e d an apparent tendency f o r the males to appear on the spawning grounds before the a r r i v a l of  74 f e m a l e s f o r Lampetra p l a n e r i . However no evidence of t h i s  was  found on the Salmon R i v e r . A p p l e g a t e (1950), Gage (1928), and W i g l e y (1959) m a i n t a i n e d  t h a t males a r r i v e d on the spawning-  a r e a b e f o r e the f e m a l e s ,  chose the l o c a t i o n , and s t a r t e d " t o  dig  the n e s t . The  l a t e r and  females were observed t o j o i n the males  a s s i s t w i t h c o n s t r u c t i o n . The above a u t h o r s  t h a t t h e r e may  suggest  be a form of t e r r i t o r i a l i t y s e t up by t h e males.  Thus, the prespawning p e r i o d i s g e n e r a l l y a time o f l i t t l e a c t i v i t y t h a t s t r e t c h e s from the end of t r a n s f o r m a t i o n to  the b e g i n n i n g  of t h e f i r s t  s i g n s of spawning. T h i s p e r i o d  i s from one month t o two weeks i n d u r a t i o n as the exact of c o m p l e t i o n  of t r a n s f o r m a t i o n and the b e g i n n i n g  spawning i s extremely  time  of p r e -  d i f f i c u l t t o d e t e r m i n e . Prespawning  extends from March t o June i n t h e Salmon R i v e r and depends on t h e m a t u r i t y of the i n d i v i d u a l Lampetra. Entosphenus L e s s i s ' known about the w i n t e r l i f e of Entosphenus t h a n Lampetra as' few have been c o l l e c t e d o r observed d u r i n g t h i s t i m e . One  specimen was  dug from between b o u l d e r s  December on t h e N i c o l a R i v e r ; a n o t h e r was  in  removed from the  g r a v e l a t n i g h t on March 15 from t h e A l o u e t t e R i v e r . Three a d u l t s n e a r i n g spawning c o n d i t i o n (sperm a c t i v e ) were  captured  a t the f i s h f e n c e a t S w e l t z e r Greek on t h e f i r s t of A p r i l . Thus a sedentary  burrowed e x i s t e n c e i s i n d i c a t e d d u r i n g the  greater  p a r t of the prespawning and w i n t e r p e r i o d w i t h m i g r a t i o n  and  movement w i t h i n the stream s t a r t i n g i n A p r i l . From aquarium o b s e r v a t i o n s  of b e h a v i o u r  during  April  75  p r i o r to spawning, the males are more a c t i v e at lower temperatures than Lampetra. Entosphenus spends part of the prespawning period r e s t i n g attached to the bottom rocks or the aquarium glass while Lampetra spends more time burrowed i n the g r a v e l , (e) F i r s t Sign of Spawning The animals leave the gravel and move to the r i f f l e areas of the stream. They were observed l i f t i n g rocks  and  moving about on the nests. They are u s u a l l y seen h i d i n g i n the shade or under rocks during t h i s e a r l y p e r i o d , while l a t e r when spawning i s more intense they are seen on the g r a v e l i n b r i g h t s u n l i g h t . I t was d i f f i c u l t to determine the f i r s t sign of spawning as the stream was not v i s i t e d d a i l y . However a form of low i n t e n s i t y nest c o n s t r u c t i o n or "play with stones" was  observed. Both males and females l i f t e d and dropped  stones haphazardly without c o n s t r u c t i o n of a nest i n any  one  l o c a l i t y . There seemed to be considerable movement w i t h i n the gravel area before nest c o n s t r u c t i o n was s t a r t e d . When adults i n the spawning or prespawning c o n d i t i o n are introduced to an aquarium they burrow i n t o the g r a v e l f o r a number of hours. The f i r s t spawning signs i n v o l v e the adult l e a v i n g the gravel and r e s t i n g attached to rocks.  Searching  the aquarium and f r a n t i c swimming around the surface of the aquarium u s u a l l y f o l l o w and rock l i f t i n g and digging by i n d i v i d u a l s occurs l a t e r . I n d i v i d u a l s may  leave the g r a v e l f o r  a short time to d i g and l i f t rocks, and swim at the surface but spend the remainder of the day r e s t i n g under the rocks. There i s a greater frequency of a c t i v i t y on the g r a v e l during  76 the  darkness hours before a c t u a l spawning  starts.  Hagelin (1959) observed a s i m i l a r r e s t l e s s behaviour i n the River Lamprey. The male often plays with stones by l i f t i n g and dropping them immediately or by a combination of l i f t i n g and swimming on the side of the body with the body arched l i k e a bow; i t g l i d e s along the bottom. These low i n t e n s i t y a c t i v i t i e s of "play with stones" and digging probably prepare the adult f o r the more vigorous behaviour of a c t u a l spawning that i s to f o l l o w . The f i r s t signs o of spawning s t a r t when the temperature r i s e s t o 11 C, IHardisty 1944 and' Schultz 1930) while the temperature f o r i n i t i a t i o n of spawning i s 12-13°C, as reported by Wigley and Hagelin (1959). o In Salmon River lampreys a temperature of l e s s than 10 G. w i l l i n i t i a t e females t o s t a r t spawning while a temperature above 10°C-  has a h i g h l y s t i m u l a t i n g e f f e c t on males. (f) Nest B u i l d i n g  Normal nest b u i l d i n g by Lampetra i n the Salmon River o commenced a f t e r the temperature rose above 10 C. but spawning o . and nest b u i l d i n g was observed at a temperature of 9 C (low temperature f o r spawning) on A p r i l 24, 1962. However, the temperature had p r e v i o u s l y r i s e n above the 10 to 11°C. apparently necessary t o i n i t i a t e the a c t i o n (Hardisty 1954). The male (above 10°C.) was the i n s t i g a t o r of nest c o n s t r u c t i o n and contributed at l e a s t two-thirds of the e f f o r t of c o n s t r u c t i o n . The female helped the male complete the nest a f t e r i t had been s t a r t e d . She contributed much l e s s to the endeavour e s p e c i a l l y a f t e r spawning had s t a r t e d , f o r much of  77  her time was spent with her body draped i n the nest with o r a l hood attached t o a rock at the edge of the nest. Nest c o n s t r u c t i o n involved three d e f i n i t e a c t i o n s on the part of e i t h e r adult:'' 1. Rock l i f t i n g was s i m i l a r to the rock play already mentioned. Small rocks l e s s than 3/4 inch i n diameter were removed t o the side of the nest. Most often the rocks were removed t o the downstream edge of the impression, but o c c a s i o n a l l y rocks were c a r r i e d upstream or to the sides of the nest, a distance of u s u a l l y not more than s i x inches. Hardisty a l s o observed  this  (1944). Rocks weighing up to 30 grams were r o l l e d or p r i e d from the nest, but rocks l e s s than 15 grams were removed e a s i l y by a lamprey swimming with i t . A lamprey needs three swimming movements per second i n order to l i f t a 2 to 4 cn. stone (Hagelin 1959)•  F i g . 39 Lampetra removing rocks from a nest i n an aquarium, (a i s removed rock)  78  In an aquarium t h e n e s t was round but i n t h e stream i t was u s u a l l y w i d e r than i t was l o n g (See Table 4 f o r s i z e s of n e s t s ) . I n an aquarium a male u s u a l l y b u i l t a nest where he s t a r t e d c o n s t r u c t i o n , but i n t h e stream he would o f t e n s t a r t /  a n e s t , p a r t i a l l y complete  i t , and then wander away t o a n e s t  o c c u p i e d by a number of o t h e r lampreys. completed  The f i r s t nest was  l a t e r by another a n i m a l o r group o f a n i m a l s .  (g) Combination  Rock L i f t i n g and D i g g i n g  T h i s a c t was performed  by lampreys  i n removing l a r g e  r o c k s from t h e n e s t . The b u c c a l f u n n e l was a t t a c h e d t o t h e r o c k , t h e body was arched i n a p r y i n g motion, and t h e t a i l performed  v i g o r o u s swimming movements. The a c t i o n was so  v i g o r o u s t h a t sand and s m a l l stones were s t i r r e d up from the bottom of t h e n e s t . H a g e l i n a n a l y s e d t h i s and found t h a t the swimming movements were a t a f r e q u e n c y of f i v e o r s i x per second.  I f t h e r o c k was v e r y l a r g e i t was r o l l e d o r c a r r i e d  a l o n g t h e bottom and out o f t h e n e s t . The lamprey o c c a s i o n a l l y t u r n e d on i t s back o r s i d e t o p r y a l a r g e stone l o o s e ; i t s body would r e s t on t h e bottom. The muscular movements  of the  head dragged o r r o l l e d t h e r o c k a s h o r t d i s t a n c e . On a number of o c c a s i o n s two lampreys were seen a t t a c h e d t o one r o c k and removed i t from t h e n e s t but t h i s was a p p a r e n t l y a chance o c c u r r e n c e r a t h e r than c o - o p e r a t i o n . (h) The D i g g i n g A c t i o n T h i s a c t i o n f o l l o w e d when t h e n e s t reached a depth of one i n c h o r when, some o f t h e s u r f a c e stones had been removed. The b u c c a l d i s c was a t t a c h e d t o a l a r g e r stone a t t h e edge of  79 Table 4. A n a l y s i s of the depth of water and current v e l o c i t y above nests occupied by spawning; adults on the Salmon River. T  f  A  B  f C  Cross-section through a Lampetra nest. Depths tabled below. SURFACE  CURRENT -  ft./sec-  H  J  T  E  "I  F  RIFFLE  POOL  .Longitudinal s e c t i o n through a Lampetra nest. Depths and current tabled below. Water Depth i n inches. Current i n f t . per sec. Lampetra  A p r i l 20/62 " 25/62 May 20/62 " 27/62  June 10/ 62 it  tt  tt  tt  tt  tt  tt  t t  t t  June 14/ 62 tt  tt  tt  June 22/ 62 it  tt  tt  Mean  A  B  C  D  15 12 12 6  15  12 12 11 5 10  15 13 12 4 5 . 11 12 6 6 8 12 9 10 9 9 7 7 5  13 13  10 12 • 10 11 10 10 7 15 13 10 14 8 7 9 9 9 9  9 9 9  8 12 11 7  9.8  11.7 9.5  16  17 18  13  E  13  F .  G  H  13  12 11 6 8  15 3 5 7 7 9  8 8 13 7  10 6 4 10 24 5  1. 5 1. 6 1. 5 1. 5 1. 6 1. 6 1. 5 1. 2 1. 2 1. 0 1. 0 1. 5 1. 4  9 9  18 9  11 7  9.7  9.6  9.4  8.8  21 21  16 12  6 15  22 23  9  Entosphenus A p r i l 20/62 A p r i l 28/62  (Abandoned).  13  11 15  1. 2-1.6 <1 ..6  80  the nest and while the animal was on i t s side the t a i l v i b r a t e d r a p i d l y at a frequency greater than seven movements per second. The sand and small rocks were l i f t e d from the bottom of the nest and f l i p p e d out of and to the sides of the nest, thus making the nest deeper ( F i g . 40).  This behaviour was undertaken  by both male and female but i n the stream at higher temperatures i t was more f r e q u e n t l y p e c u l i a r to the male. Rock l i f t i n g can f o l l o w digging but u s u a l l y digging immediately preceded the spawning act when the nest i s completed or a f t e r spawning has started.  Fig.  40 Lampetra i n an aquarium nest d i s p l a y i n g digging a c t i o n . ( a i s a digging adult) Digging serves to loosen the bottom and l i n e the  bottom of the nest with sand which i s important f o r anchoring the eggs i n the nest. From observations i t i s apparent that the vigorous digging a c t i o n a l s o serves to move the sex products to the u r o g e n i t a l opening as only a few eggs are l a i d and released from the main egg mass at a time, s t a r t i n g from the p o s t e r i o r end and proceeding forward.  81 Entosphenus The behaviour of Entosphenus d i f f e r s from.that of Lampetra only i n the i n t e n s i t y of the a c t i o n s , the s i z e of the nest, and i t s l o c a t i o n i n the stream. Table 4 shows the l a r g e r dimensions of the nest and F i g . 41 shows a cross section of an Entosphenus nest. A comparison between Salmon R i v e r lampreys taken from the nest and the nest stones i s shown i n F i g . 38. A spawning p a i r was observed f o r a f i v e hour period i n the Salmon River on A p r i l 20, 1962. They.deposited eggs r e g u l a r l y every two to f i v e minutes throughout the observation period. Nest c o n s t r u c t i o n and digging was c a r r i e d on between spawning acts w i t h the-males c o n t r i b u t i n g the m a j o r i t y of the e f f o r t . However, the female contributed some rock l i f t i n g and digging between every spawning. Rocks weighing 660 grams were  SURFACE  CURRENT  1.6  ft./sec.  RIFFLE II  POOL 16 17  F i g . 41 L o n g i t u d i n a l s e c t i o n through a nest constructed by a p a i r of large Entosphenus (2> 400 mm.) on the Salmon River.  82  observed being r o l l e d from the nest. Both adults were observed l i f t i n g together a l a r g e rock from the nest, but as with Lampetra t h i s i s apparently a chance matter of both lampreys a t t a c h i n g to the same rock at. one time. ( i ) Courting  Behaviour  This behaviour i s u s u a l l y confined to the nest s i t e and i s most often e x h i b i t e d by the male, but females do d i s p l a y a s i m i l a r behaviour. The male and the female are u s u a l l y seen j o i n t l y b u i l d i n g the nest. The female, j u s t p r i o r to release of eggs, r e s t s i n the nest with her buccal d i s c attached to rocks at the upper edge of the nest while the male continues to d i g and l i f t rocks from the nest. Her body l i e s curved i n the bottom of the nest and. undulates slowly back and f o r t h . The male passes over and under her body as he digs. She may d i g , r e s t , and undulate again. Usually just a f t e r d i g g i n g , followed by a short r e s t , the male moves to the bottom of the nest and touches the female's body with h i s buccal d i s c and moves, with a " g l i d i n g - f e e l i n g " motion , up her body t o the top of her head. Hagelin (1959) describes a c o u r t i n g or prespawning behaviour i n L. f l u v i a t i l u s i n which the.female  swims i n  c i r c l e s over the n e s t - c o n s t r u c t i n g male. As she passes over the nest she sinks down so that part of her abdomen passes over the male's head at f i v e or s i x second i n t e r v a l s at each excursion. These c o u r t i n g c i r c l e s were not observed i n L. p l a n e r i , nor was there any•violent shaking by the female i n the nest; Hagelin may have i n t e r p r e t e d the digging behaviour as  83  s h a k i n g . However, a s h a k i n g b e h a v i o u r was observed  when t h e  female was a t t a c h e d t o t h e aquarium g l a s s . The Salmon R i v e r female  lampreys were a l s o  observed  c o u r t i n g w i t h g l i d e - f e e l i n g advances t o a male not on a n e s t . T h i s was observed  toward  o t h e r females  i n the nest at v a r i o u s  t i m e s , as i s shown i n F i g . 42A. This shows t h r e e  females  o c c u p y i n g one nest but no male i s p r e s e n t on t h e day which f o l l o w e d h i g h communal spawning. The two o u t s i d e females i n the f i g u r e a r e u n d u l a t i n g and t h e c e n t r e female has completed a c o u r t i n g g l i d e up t h e female  attached t o the g l a s s . This  method o f attachment o f a female t o a n o t h e r lamprey was not as f o r c e f u l and o n l y on r a r e o c c a s i o n s was t h e r e a r c h i n g of the f o r e b o d y  or v i g o r o u s v i b r a t i o n s . However, when two  are a l l o w e d t o spawn w i t h o u t t h e presence  females  of a male t h e y  u s u a l l y both a t t a c h t h e b u c c a l d i s c t o t h e g l a s s or a r o c k and v i b r a t e v i g o r o u s l y w i t h t h e i r bodies t o u c h i n g . Eggs were observed  b e i n g r e l e a s e d w i t h each v i b r a t i o n u n t i l a l l eggs  were spawned i n a week's t i m e . A low i n t e n s i t y , of c o u r t i n g i n v o l v e s t h e r u b b i n g of the body o f one s e x a g a i n s t , under, o r over t h e body o f a n o t h e r . T h i s a p p a r e n t l y tends t o s t i m u l a t e t h e l e s s r e c e p t i v e p a r t n e r i n t o a c t i v i t y , o r i t may i n c r e a s e t h e g e n e r a l p i t c h o f spawning a c t i v i t y o f a communal nest.. A s i m i l a r b e h a v i o u r was  observed  when one male had j u s t dug a n e s t but no females were t o be found on t h e g r a v e l . Here t h e male went t o t h e c o r n e r o f t h e tank where t h e o t h e r a d u l t s were and burrowed under t h e rocks., t w i s t i n g h i s body about and a g a i n s t t h e o t h e r s , thus a p p a r e n t l y e x c i t i n g them i n t o a c t i o n .  84 Entosphenus Observations of paired and one communal spawning of Entosphenus showed that the courting a c t i o n of the male i s very pronounced. The female courted or g l i d e d over the male only on one or two occasions. Usually spawning followed the f i r s t or second c o u r t i n g g l i d e of a male over a female. The buccal d i s c i n male Entosphenus seemed to be used more i n grasping and courting than i n Lampetra. The i n t e n s i t y of courting i n the one instance of communal spawning was that of f i v e adults nest b u i l d i n g only. No spawning a c t u a l l y took place during the observation period, (j) Spawning; Act A few courting movements immediately precede spawning. Here the male g l i d e s and f e e l s up the female's body to a p o s i t i o n above her buccal d i s c . He attaches h i s buccal d i s c to the  top of her head ( F i g . 42C) and arches h i s forebody. This  i s followed'by the same behaviour from the female,, plus undulation of her body. The male t w i s t s h i s t a i l around the body of the female and both lampreys v i b r a t e v i g o r o u s l y . Both lampreys stop v i b r a t i n g and the male r e l i n q u i s h e s h i s head and t a i l hold on the female ( F i g . 42D) . The eggs and sperms are released by the animals during t h i s short i n t e r v a l . The a c t i o n of the v i b r a t i o n s may be so vigorous that the rock to which the  female i s attached i s p u l l e d from the edge of the nest,  or the female may be dislodged from the glass i n an aquarium. The t a i l of the female i s forced i n t o the loose sand, or against i t i n a v e r t i c a l p o s i t i o n , at the bottom of the nest  35  F i g . 42  Spawning sequence of L . p l a n e r i i n an aquarium. A- females undulating i n nest w a i t i n g f o r a male. B- male courting or g l i d i n g up the body of female. C- male grasps female by the head and t w i s t s h i s t a i l around her body, both v i b r a t e and release sex products. D- male releases the head hold, both stop v i b r a t i n g .  86 as t h e eggs and sperms a r e r e l e a s e d ( F i g . 43A, 43B, 43C). The f o r c e d v i b r a t i o n s cause t h e sand i n t h e n e s t t o be s t i r r e d up i n a c l o u d . The eggs, h e a v i e r than w a t e r , a r e a d h e s i v e and become a t t a c h e d t o g r a i n s o f sand which s i n k t o t h e bottom o f the  n e s t and a r e covered by t h e c l o u d o f sand. When t h e n e s t  was examined the  a f t e r a spawning a c t , no eggs c o u l d be seen a t  s u r f a c e . The p a p i l l a o f b o t h a n i m a l s may be c o m p l e t e l y  b u r i e d i n t h e sand so t h a t t h e eggs a r e a c t u a l l y r e l e a s e d below t h e s u r f a c e o f t h e n e s t bottom  1  ( F i g . 43A, 4 3 ) . The t a i l c  p o s i t i o n o f t h e female i s i n a v e r t i c a l p l a n e ( F i g . 45)  which  i s q u i t e d i f f e r e n t from t h e p o s i t i o n o f d i g g i n g , and t h e sand i s n o t sucked from t h e n e s t as i n t h e l a t t e r c a s e . The i n t e n s i t y of t h e v i b r a t i o n s i s g r e a t e r i n t h e spawning a c t than i n t h e digging action. More t h a n one p a i r o f lampreys have been observed i n the  spawning a c t a t one time..One male has been observed  spawning w i t h two females s i m u l t a n e o u s l y . The male g r a s p s one of two females t h a t a r e u n d u l a t i n g s i d e by s i d e ; he throws h i s t a i l around one female t h a t he has a t t a c h e d t o and b e g i n s t o v i b r a t e , as do b o t h f e m a l e s . I t was not seen whether both f e m a l e s r e l e a s e d eggs o r n o t . Two males were a l s o observed t o g r a s p t h e same female a t t h e same t i m e . Both grasped h e r on the  head and wrapped t h e i r t a i l s around her body as i s c h a r a c -  t e r i s t i c o f t h e p a i r e d b e h a v i o u r . A l s o , t h e males a r c h e d t h e i r b o d i e s and v i b r a t e d v i o l e n t l y , w i t h r e l e a s e o f s e x p r o d u c t s . There was no e v i d e n c e o f p a i r bond f o r m a t i o n as males and f e males spawned f r e e l y w i t h any p a r t n e r o f t h e o p p o s i t e s e x t h a t  87 was a v a i l a b l e a f t e r the required p h y s i o l o g i c a l and behaviour stimuli. Hagelin (1958) found that L. f l u v i a t i l u s males always approached, the females from the l e f t side but t h i s d i d not prove to be true f o r L. p l a n e r i or E. t r i d e n t a t u s i n the Salmon R i v e r . These males appeared to approach the female from whichever side was convenient ( F i g . 43 & 4 4 ) . More approaches were from the r i g h t than from the l e f t but t h i s i s due to the current coming from the l e f t and the glass prevented advances from the  l e f t with ease. A f t e r each spawning by a p a i r there i s a short r e s t  period during which the female u s u a l l y r e s t s i n the nest while the  male u s u a l l y leaves the nest f o r a short time. He u s u a l l y  wanders i n a c i r c l e around the nest, or he may j o i n another nest to spawn with another female. On occasions both animals remain i n the nest with the male r e s t i n g beside the female or attached to her. When the male'returns to the nest he s t a r t s rock l i f t i n g again and the digging motion. The nest i s u s u a l l y enlarged i n an upstream d i r e c t i o n ; the eggs deposited are not disturbed by f u r t h e r spawning. The sequence of spawning, r e b u i l d i n g the nest, and c o u r t i n g can be predicted and analysed with p r e c i s i o n as a s e r i e s of steps. A c t i v e spawning f i r s t takes place at i n t e r v a l s of about f i v e minutes. Later the a c t i v i t y i s reduced and  may  occur only every few days or not a i a l l a f t e r the major deposi t i o n of eggs. Most of the eggs from one female are l a i d w i t h i n 12 hours. A f t e r t h i s the spawning a c t i v i t y i s reduced and the  88  F i g . 43  Communal spawning showing the p o s i t i o n taken by the male i n grasping the head of the female, tf and C- three a d u l t s spawning at once.  89  F i g . 44  Communal spawning showing the p o s i t i o n of the t a i l of both sexes. A rock i s being r o l l e d from the nest i n D.  90 female slowly d i e s . However, a c t i v e spawning has not been observed very f r e q u e n t l y because females with egg-swollen bodies are seldom seen. Spawned out and p a r t l y spawned out females are quite commonly observed spawning i n the f i e l d  and  i n the l a b o r a t o r y . This tends to i n d i c a t e that the i n i t i a l  and  most a c t i v e spawning takes place at night e a r l y i n the season. Entosphenus The a c t u a l spawning, as nest b u i l d i n g , was more intense f o r Entosphenus than was  observed i n Lampetra. The  male grasps the female very f i r m l y on the top of the buccal d i s c or head l e a v i n g tooth impressions from h i s sharp t e e t h . The v i b r a t i o n s that f o l l o w the t w i s t i n g of the t a i l around the female and the arching of both bodies are very intense. Sex products are released i n t o the cloud of sand p a r t i c l e s . and small stones. I t was d i f f i c u l t to see the exact number of eggs released at each spawning, but 100-500 eggs was  the  estimated number released. (k) I n t e r n a l F e r t i l i z a t i o n Much controversy e x i s t s as to whether or not i n t r o m i s s i o n occurs i n lampreys as reported by Dean, Basford, and Surrjner (1897) and Loman (1912). Observations  on Salmon  River lampreys agree favourably with Hagelin (1959) and show c l e a r l y that i n t e r n a l f e r t i l i z a t i o n  i s impossible because of  the p o s i t i o n of the bodies during the spawning act ( F i g . 42D, 44D,  and 45). The f a r t h e s t distance p o s t e r i o r that the t a i l  of the male can s t r e t c h , yet s t i l l e n c i r c l e the female's body, i s to the second d o r s a l f i n s w e l l i n g . When the t a i l i s wound  91 i n t h i s p o s i t i o n the u r o g e n i t a l openings are s t i l l several centimeters from each other. This i s so i n both Lampetra and Entosphenus ( F i g . 45, distance A). Intromission does not occur i n B r i t i s h Columbia lampreys.  F i g . 45 Spawning Lampetra showing the distance (A) between the u r o g e n i t a l openings during the spawning a c t . (1) Length of Spawning and Post Spawning Period I t was d i f f i c u l t to d i f f e r e n t i a t e between the spawning period and the post spawning period. I t was p o s s i b l e to t e l l when females had released most of t h e i r eggs because t h e i r abdomens became transparent during spawning. Most females died w i t h i n two weeks of the release of a l l t h e i r eggs, but spawning and post spawning period duration depended upon water temperature ( F i g . 4 6 ) . Usually l e s s than ten eggs remained i n the body c a v i t y when the female died (Table 3 ) . The time when males released a l l t h e i r sperms could not be determined without d i s section.  The post spawning period could not be  differentiated  92  DYING  PERIOD MALES  80  FEMALES  70  MEAN  60  \  50  \ n  cn  Q O  g cc  £30  o z z <  0.  U)20  u.  o  5 10  16-20 (9? I6<3» ) 8-10 (6? 3*) JI-15 U $ 5* ) TEMPERATURE IN °C FIG. 46.LENGTH OF THE SPAWNING PERIOD AT DIFFERENT TEMPERATURES FOR LAMPETRA PLANERI OF THE SALMON RIVER.  93  from the spawning period i n males. Most males died with much of the sperm s t i l l remaining w i t h i n t h e i r bodies. Hagelin and S t e f f n e r (1958) reported that a l l r i v e r lamprey died about one week a f t e r the l a s t eggs were deposited These researchers a t t r i b u t e death t o a long f a s t i n g period p r i o r to spawning and a r a p i d use of energy during spawning. Numerous dead adults i n a spawned out c o n d i t i o n were c o l l e c t e d from the 20th. of March to the f i r s t week i n June from the Salmon R i v e r . A l l Salmon River lampreys kept i n aquaria died. The spawning period, and post spawning period f o r L. p l a n e r i from the Salmon River extended from the middle of A p r i l t o the second week i n J u l y . Animals were c o n t i n u a l l y reaching maturity and dying throughout t h i s period. Dying and spawned out adults are c h a r a c t e r i z e d by marked reduction i n the abdomen diameter, f a d i n g and blotched c o l o u r a t i o n , and blood f i l l i n g the t i s s u e s of t h e f i n s , buccal d i s c , and region of the vent. A.number of dying a d u l t s have been observed going through r a p i d t w i s t i n g movements and convulsions. The bodies of dead lampreys are covered with .fung w i t h i n a day of death i n the r i v e r and i n the aquarium. Gage (1928) and Applegate (1950) observed that dead and dying Sea Lampreys are deposited i n deep and s i l t e d pools. Entosphenus The spawning period seemed t o extend from A p r i l 20 to June 22 during 1962 according t o specimens observed on the Salmon R i v e r . N i l e Creek specimens were caught i n spawning c o n d i t i o n as l a t e as the f i r s t week i n J u l y while spawning  94  movement was recorded as e a r l y as March from 1948 to 1954. Mattson (1949) reported Entosphenus spawning on the Willamette R i v e r , Oregon, i n June and J u l y . Aquarium spawning and holding experiments were not c a r r i e d out f o r Entosphenus. (m) Communal Spawning. The communal and gregarious sharing of spawning nests and partners i s extremely i n t e r e s t i n g to analyse as to f u n c t i o n and s i g n i f i c a n c e . This behaviour of L. p l a n e r i has u s u a l l y been observed during the beginning of the season or when a number of r i p e animals have j u s t been introduced i n t o an aquarium. S i x communal spawnings have been observed i n the stream during A p r i l and e a r l y May,' but none were observed during June or e a r l y J u l y . This may be due to a decrease i n the  d e n s i t y of the spawners i n the l a t e r part of the season. As many as twelve'adults have been observed i n one  nest and a l l seemed to be p a r t i c i p a t i n g i n the spawning. There was u s u a l l y much m o b i l i t y w i t h i n the.group, and when communal spawning was observed f o r a number of hours, the group broke up i n t o three or more groups, each spreading out to neighboring nests with spawning occurring i n each group. Ten minutes l a t e r the m a j o r i t y of them were back -in the f i r s t communal nest. There seemed t o be some rhythm of spawning where two or three p a i r s would be spawning very close to each other. Then most of the  group would leave the nest to v i s i t other nests, but they  would return i n about f i v e minutes to resume digging and spawning. Aquarium observations bear out the notion of rhythmic  95 communal spawning. The males are- the a c t i v e p a r t i c i p a n t s i n n e s t c o n s t r u c t i o n and enlargement o f t h e n e s t between spawnings, and the females u s u a l l y t a k e a l e s s a c t i v e p a r t i n the p r o cedure. Communal spawning r e p r e s e n t s the h i g h e s t a c t i v i t y  level  i n spawning w h i c h o c c u r s f o r a p e r i o d of one day or l e s s . A p a r t i c u l a r b e h a v i o u r i s a s s o c i a t e d w i t h communal spawning t h a t has never been r e p o r t e d b e f o r e . That i s the c o i l i n g of e i t h e r a male o r female around a spawning p a i r o r around two spawning p a i r s , or c o i l i n g near a p a i r ( F i g . 4 7 ) . T h i s b e h a v i o u r was examined w i t h the a i d o f a motion, p i c t u r e and i t was  c o n c l u d e d t h a t i t may  s e r v e t o b i n d a group o f  s t i m u l a t e d b o d i e s t o r e l e a s e sex p r o d u c t s at one t i m e , but whether o r not t h e c o i l i n g a d u l t d i d r e l e a s e sex p r o d u c t s i s not known. However, t h e c o i l i n g i n d i v i d u a l was  seemingly  s t i m u l a t e d by the v i b r a t i o n s . I t c o u l d s e r v e t o h o l d t h e sex p r o d u c t s t o g e t h e r and ensure f e r t i l i z a t i o n , o r i t may  be  s i m p l y a v i b r a t i n g and c o i l i n g r e a c t i o n o f a number o f h i g h l y s t i m u l a t e d a n i m a l s when one p a i r s e t s o f f the t r i g g e r mechanism of t h e spawning a c t . I t i s s u s p e c t e d t h a t . d u r i n g communal spawning a c h e m i c a l r e l e a s e r s t i m u l a t e s lampreys t o congregate a t a communal n e s t . A r i p e unspawned female was i n t r o d u c e d i n t o a t a n k c o n t a i n i n g f o u r males and she was removed a f t e r a f i v e  v  minute s t a y . The presence of the female a p p a r e n t l y caused the males t o become v e r y a c t i v e and t h e y l i f t e d r o c k s and dug f o r a two hour p e r i o d a f t e r t h e female was removed from the t a n k . R i p e unspawned females seemed t o  be always p r e s e n t i n t h e  96  F i g . 47  C o i l i n g a c t i o n during communal spawning. A male or a female c o i l s around the spawning p a i r ( centre of each p i c t u r e ) .  97 communal nest. This suggests that females may give o f f a chemical r e l e a s e r that congregates a number of lampreys to one nest for communal spawning. Communal spawning has been recorded f o r P. b r a n c h i a l i s , brook lamprey of New York, by Gage (1893 and 192$) when eight to ten animals spawned i n one nest. Hubbs and Trautman . (1937) reported from f i v e to nine i n d i v i d u a l s per nest f o r Ichthyomyzon greeneyi. Schultz observed nine L . p l a n e r i i n a communal nest i n Washington State near the s t a r t of the spawning season. Dendy and Scott (1953) reported from f i v e to twenty lampreys i n a communal nest f o r Ichyomyzon gagei but they observed great v a r i e t y i n numbers. Entosphenus Communal spawning was observed i n the Salmon River on one occasion when two l a r g e Entosphenus ( l a r g e r than 5 5 0 mm.) were seen i n one nest w i t h three smaller i n d i v i d u a l s (less than 2 5 0 mm.). However, the spawning act was not observed although rock l i f t i n g and digging were. L a t e r d i s s e c t i o n revealed the animals were i n a spawned out c o n d i t i o n . The difference i n s i z e between the two s i z e ranges seemed to have no effect on communal spawning. A large female and a small male were c o l l e c t e d and spawned a r t i f i c i a l l y the f o l l o w i n g day. The few < eggs that were obtained hatched i n the l a b o r a t o r y . Communal spawning does occur i n Entosphenus but u s u a l l y the population on the Salmon River was so small that i n some years only p a i r s or s i n g l e i n d i v i d u a l s were c o l l e c t e d .  98  (n) Displacement  Behaviour  Spawning "displacement" behaviour occurs most f r e q u e n t l y "when a c e n t r a l nervous mechanism has been s t i m u l a t e d but cannot use i t s normal o u t l e t because the p a r t i c u l a r a c t i v i t y i s not p o s s i b l e . " (Baerends 1957). In lamprey spawning behaviour there i s a normal s e r i e s of steps that each animal goes through before the sex a c t . I f the, animal s t a r t s spawning by proceeding through one or more steps, as digging a nest, but i s prevented from completing the s e r i e s , t h e n a d i f f e r e n t "displacement" behaviour i s observed. This "displacement" behaviour i s q u i t e d i f f e r e n t from the normal sequence of spawning behaviour. I t u s u a l l y takes the form of r e v e r t i n g to a lower step of the normal s e r i e s , when the other partner i s e i t h e r not ready to complete the sex act at a p a r t i c u l a r time, or i s absent. One partner i s p h y s i o l o g i c a l l y ready t o spawn yet the other does not complete the necessary response when the sign stimulus i s a p p l i e d by the other partner. The energy i s u s u a l l y channeled i n t o an a c t i o n that i s s i m i l a r t o , or r e v e r t s t o , e a r l y spawning behaviour. One form of displacement behaviour occurs when a s i n g l e male or female has completed nest c o n s t r u c t i o n alone and no partner of the opposite sex i s present i n the nest t o complete the spawning a c t . The i n t e n s i t y of d i g g i n g i s u s u a l l y increased u n t i l the animal swims a c t i v e l y around the tank as i f searching f o r a spawning partner. I f the a c t i v e l y swimming adult i s a male, he w i l l seek out another lamprey and court the animal by moving h i s buccal funnel up the animal's body. I f the  99  r e c e i v e r i s a male he w i l l move away from the advancing male with quick swimming and w r i g g l i n g motions. I f the r e c e i v e r i s a female she w i l l move from the gravel and swim around the tank and s e t t l e i n the nest i f she i s ready t o spawn. I f the female i s not ready t o spawn she w i l l remain burrowed or attached t o the  rock. The male responds by c o n t i n u a l l y courting or g l i d i n g  over her body with f e e l i n g motions with the buccal d i s c ( F i g . 42B). On a number of occasions the male attached h i s buccal d i s c t o the head, or b r a c h i a l region of the female and swam or p u l l e d her to the nest. Two spawned out and nearly dead females were observed being c a r r i e d by the male t o the nest. Once at the nest, the male proceeded t o court and stimulate the  female f o r ten minutes. The male attached t o the female's  head and wrapped h i s t a i l around her abdomen but the female did not respond with the undulations or v i b r a t i o n s of normal spawning. The i n t e n s i t y of the male's c o u r t i n g and attachments increased u n t i l the male went through the v i b r a t i o n s of spawning and t a i l t w i s t i n g w i t h sperm release without any female response or r e l e a s e . This continued f o r one hour the  until  female f i n a l l y d i e d , but the male continued t o c a r r y the  female on t o the nest and around the tank. The male l e f t the dead female and burrowed deeply i n t o the g r a v e l on a number of occasions but returned to carry the female about the tank again. He f i n a l l y l e f t the female and reverted t o c o n s t r u c t i o n of the nest by r a p i d digging. Females were observed "searching" f o r a male a f t e r completing nest c o n s t r u c t i o n . When she located a male she  100  would court him with g l i d i n g motions s i m i l a r to those used by the male ( F i g . 48). Males u s u a l l y responded by r e t u r n i n g to the female's nest, but i f not responsive they would  burrow  deeper under the rocks. Once i n the nest, a responsive male would take the i n i t i a t i v e and perform the spawning a c t .  F i g . 4 8 A female c o u r t i n g a male by g l i d i n g along h i s body. Females ready to spawn were observed c o u r t i n g other females by g l i d i n g up t h e i r bodies or a t t a c h i n g t o the head of the other female and undulating the body. On one occasion one female arched the b r a c h i a l region and v i b r a t e d r a p i d l y while attached to another female, but the female never wrapped her t a i l around another lamprey. Two females kept i n one tank released t h e i r eggs by grasping the glass and v i b r a t i n g both bodies r a p i d l y and close together i n the sand. Females ready to spawn and unable to arouse a male l i e f o r long periods with t h e i r bodies curved i n the nest and undulating slowly. Occasionally the female w i l l d i g up the bottom of the nest, l i f t rocks or attach to the glass of the tank and v i b r a t e her  101 body r a p i d l y as i n the spawning or digging a c t i o n . Males kept i n a tank without females b u i l t nests and rested i n them. A common behaviour during t h i s time was the crooking of the t a i l as described by Hagelin (1959). Separated males t r i e d t o court other males but the r e c e i v e r always moved out of the g r a v e l q u i c k l y . Hagelin (1959) describes t h i s a c t i o n as one male r e p e l l i n g the other from the nest but i t seemed more an a c t i o n of one male not responding to the sexual advances of another male. Males kept together also displayed f r a n t i c swimming and searching of the tank. Males separated from females f o r a week immediately -became a c t i v e and s t a r t e d digging and rock l i f t i n g when a female was introduced i n t o the tank f o r a. short period. (o) The E f f e c t of Temperature on Spawning E f f e c t on Behaviour Three tanks were set up to t e s t the e f f e c t of d i f f e r e n t temperatures on behaviour. The f o l l o w i n g temperature ranges were e s t a b l i s h e d i n the three tanks: 8-10°C., 11-15°C , and 16-20°C . The two cold tanks were arranged w i t h c h l o r i n e f r e e c i r c u l a t i n g water to cool the tanks to the correct temperature. The warmest tank was a closed system'with aerated •water at room temperature. A l l the animals i n the warmest tank (16-20°C ) began to d i g nests a f t e r the f i r s t day of r e l o c a t i o n from t h e i r Salmon River spawning area. Communal spawning was observed a f t e r the f i r s t day of i n t r o d u c t i o n as r i p e females were present. Nest c o n s t r u c t i o n was u s u a l l y i n i t i a t e d by the males w i t h the females o f f e r i n g some a s s i s t a n c e a f t e r the nest was s t a r t e d .  •102. The males u s u a l l y l e f t the nest f o r short periods a f t e r each spawning act while the females remained i n or near the nest. Displacement behaviour was very common i n the males. The males buried i n t o the g r a v e l f o r the f i r s t day i n the 11-15°C. tank while the females rested attached to rocks or the aquarium g l a s s . Rock l i f t i n g and digging was observed i n most females during t h i s time. The males l e f t the g r a v e l on the second day f o r short periods to help the females with nest c o n s t r u c t i o n . The males' a c t i v i t y was spasmodic as they spent most of each day buried i n the rocks. Females d i s p l a y e d displacement behaviour when males were buried or i n a c t i v e . Spawning was observed i n pairs, and communally on the second  day  a f t e r i n t r o d u c t i o n . Paired spawning and nest c o n s t r u c t i o n i n i t i a t e d by both sexes was observed at frequent i n t e r v a l s during the f i r s t week. Two females died at the end of the f i r s t week and the two remaining females were i n a spawned out and emaciated c o n d i t i o n and showed no more spawning a c t i o n u n t i l death. The remaining males e x h i b i t e d displacement behaviour a f t e r the a c t i v e females died. The males remained hidden under stones i n the coldest tank (8-10°C\) f o r two weeks a f t e r i n t r o d u c t i o n . Females h i d under rocks f o r the f i r s t week but then they began to take p e r i o d i c exploratory excursions around the tank. O c c a s i o n a l l y nest c o n s t r u c t i o n was s t a r t e d by females during the second week. At the end of the second week a male o c c a s i o n a l l y l e f t the g r a v e l to spawn with females that were a c t i v e l y occupying and digging n e s t s . Females e x h i b i t e d c o u r t i n g and displacement  103  spawning behaviour toward both males and females at t h i s time. Communal spawning was observed and f i l m e d on the 1 4 t h . day a f t e r i n t r o d u c t i o n and i t occurred between s i x females and three males. Occasionally one of the males burrowed i n the gravel would j o i n the spawning group only to return to the gravel s h o r t l y . The females i n i t i a t e d . t h e nest b u i l d i n g and contributed most of the labour while the males undertook l i t t l e rock l i f t i n g and digging. A f t e r each spawning act the female, l e f t the nest while the males remained i n the nest which i s d i r e c t l y opposite to the behaviour at high temperatures. The spawning act was observed every 3 to 30 minutes depending on the number of males i n the communal nest. The females l e f t the  communal nest a f t e r each spawning act or c o i l i n g a c t i o n  while the males remained i n the nest. A l l the females returned to the nest at r e g u l a r i n t e r v a l s to d i g and spawn. A c t i v e communal spawning took place over a 1 4 hour period and began to decrease i n i n t e n s i t y a f t e r t h i s because most of the males went i n t o h i d i n g again and the r i p e females had released most of t h e i r eggs. Paired spawning was observed f o r the week f o l l o w i n g communal spawning with displacement behaviour being displayed very f r e q u e n t l y by the females. L i t t l e digging and no spawning was observed during the 1 2 - 1 6 of May f o r the males and the females i n the cold tank. Two of these i n a c t i v e males and females were removed from the c o l d tank and placed i n cold water that was allowed to warm g r a d u a l l y to room temperature (16-20°C  ) . The two males became very a c t i v e when the  104 o temperature reached 14-16 C . They swam around the tank and immediately began f r a n t i c a l l y t o d i g two separate nests. Spawning was observed immediately upon nest completion and f o r the next day. The males l e f t the nest a f t e r each spawning a c t while the females remained i n the nest. However, the females were i n a spawned out c o n d i t i o n during the second day and d i d not have much energy to c o n t r i b u t e to spawning during t h i s time. Both females died the second day a f t e r t r a n s f e r to the warm tank. Displacement behaviour was f r e q u e n t l y displayed, between the two males and between the males and the dying or dead females. On the second day the males were returned t o the cold tank. Their a c t i v e behaviour stopped immediately and they burrowed i n t o the g r a v e l f o r the next two days. The females i n the c o l d tank were n e a r l y a l l dead a f t e r one month from c o l l e c t i o n ; only o c c a s i o n a l digging or spawning was observed. The males displayed frequent d i s p l a c e ment behaviour a f t e r the females died. P e r i o d i c a c t i v e swimming at the surface was observed at i n t e r v a l s - as was hiding i n the g r a v e l . A f t e r 50 days from i n t r o d u c t i o n the a c t i v i t y of the males decreased and a l l d i g g i n g . a c t i v i t y stopped. The low temperature had a d e f i n i t e e f f e c t on reducing the a c t i v i t y and changing the behaviour of the lampreys. E f f e c t on Length of Post Spawning Period ' H a r d i s t y (1961) and Zanandrea  (1961) suggest that  Brook Lamprey d i e soon a f t e r spawning and that males l i v e longer than females during the spawning season. Lampreys from the Salmon River were placed i n  105  experimental l a b o r a t o r y tanks at three d i f f e r e n t temperatures and the date of death was recorded f o r each i n d i v i d u a l (as described above). The s i x females kept at the coldest temperature (8-10°C.) died from 14 t o 36 days a f t e r c o l l e c t i o n , but those kept at 11-15°C>  died from 4 to 23 days a f t e r  c o l l e c t i o n , and those kept at 16-20°C. died from 3 to 10 days a f t e r c o l l e c t i o n ( F i g . 4 6 ) . The males l i v e d f o r a s i g n i f i c a n t l y longer time than the females over a l l three temperature ranges. At cold temperature (8-10°Cj the males survived f o r more than twice the length of the post spawning period as shown by the females. Low temperature increases^the post spawning period of both males and females, while warm temperatures shorten the post spawning period ( F i g . 4 6 ) . C. Ammocoete L i f e 1. Method of Hatching Lamprey Eggs Lampetra eggs were c o l l e c t e d from the gravel of the spawning tank i n 1 9 6 2 , and placed i n nylon c l o t h baskets. These 4 x 4 x 4-inch baskets were suspended i n a f i v e - g a l l o n  aquarium  at' room temperature (l6-20°C ) and an a i r stone c i r c u l a t e d the water i n each container. The time of hatching and general behaviour of the young ammocoetes was observed. Some eggs were allowed to hatch and develop i n the g r a v e l . In 1 9 6 3 , g g e  s  from mature Lampetra and a spawned out  Entosphenus were f e r t i l i z e d and placed i n nylon baskets i n a f i v e - g a l l o n g l a s s aquarium (16-18°C temperature), and i n a 15°C. t h e r m o s t a t i c a l l y c o n t r o l l e d f i f t e e n - g a l l o n plywood tank.  106 Air  stones were supplied to the baskets at each temperature  and f i v e days a f t e r hatching, a one-inch l a y e r of r e c e n t l y c o l l e c t e d Salmon River s i l t was added to the baskets. Observations of hatching time, absorption of yolk sac, and behaviour of young ammocoetes were recorded. 2. Embryonic and E a r l y L a r v a l L i f e The lamprey egg, when l a i d , i s s u f f i c i e n t l y dense to sink quite r a p i d l y i n f r e s h water (Hardisty 1957). The  egg  i s adhesive at t h i s time and attaches i t s e l f f i r m l y to any surface that i t contacts. The p e r i v i t e l l i n e space between the chorion and the ovum f i l l s with water and the egg loses i t s adhesiveness two hours a f t e r i t i s released. F e r t i l i z a t i o n w i l l not take place a f t e r one hour from the release of the egg (Hardisty 1957). Cleavage takes place r a p i d l y i n lamprey eggs, the b l a s t u l a forming during the f i r s t three days ( P i a v i s I960, Hardisty 1957). P i a v i s (I960) describes 18 stages of the sea lamprey embryo before i t developed i n t o a l a r v a at 33 to 40 days. The development of Lampetra embryos was  compared to the  stages and d e s c r i p t i o n o u t l i n e d by P i a v i s . 3. Hatching  Results  The 1962 Lampetra eggs hatched.after 15 days at l6-20°C , and at 30 days the larvae were a c t i v e l y burrowing i n t o the bottom of the containers. The recently-hatched  and  older larvae were very s e n s i t i v e to l i g h t , as digging and movement could be i n i t i a t e d by exposing them to a b r i g h t l i g h t or a r t i f i c i a l l i g h t . Young (1935) and Harden-Jones (1955) have shown that the ammocoete's t a i l and other parts of the body  107 are  p a r t i c u l a r l y s e n s i t i v e t o l i g h t and that the animals show  a photokinesis.  This i s a locomotory r e a c t i o n to l i g h t ,  bearing no d i r e c t i o n a l r e l a t i o n s h i p to the source of stimul a t i o n , and the movement i s random when exposed to l i g h t . The young embryo remained at the bottom surface of containers f o r the  f i r s t two weeks before development was complete, where-  upon i t burrowed i n t o the mud t o begin the l a r v a l f o s s o r i a l l i f e . Two larvae remained a l i v e u n t i l November 8 (hatched May 29) and a t t a i n e d a length of 18  mm..  In 1963 a b e t t e r c o n t r o l of temperature was obtained and eggs of both Entosphenus and Lampetra were hatched. Lampetra hatching s t a r t e d a f t e r 13 days at 17°C  and a f t e r  15 days at 15°C. . Hatching was u s u a l l y complete a f t e r 3 days from the f i r s t sign of hatching. Entosphenus eggs s t a r t e d hatching a f t e r 19 days at 15°C- and the larvae were 1 to 2 mm. longer than Lampetra a f t e r 40 days i n the same temperature bath. N a t u r a l l y spawned eggs were hatched at 8-9°^  i n 25 days.  C a r l (1945) reported that i t took 28 days to hatch Lampetra at 10-20°C  from Holmes Creek near Cowichan Lake. Hardisty  (1957) performed extensive hatching experiments on E n g l i s h Brook Lamprey eggs, and found that they hatched i n 17 days at 11-12°C.. and i n 21 days at' 9-10°C , . He hatched eggs successf u l l y i n 3-5°C  conditions a f t e r 8 weeks. The stages of  embryonic development of Entosphenus and Lampetra were very s i m i l a r to that described by P i a v i s (I960) f o r the sea lamprey. Gage (1928) hatched sea lamprey i n nine days at 60°F , Wigley (1959) i n 14 days at 60°F , and L©nnon(l955) i n 10 to  108 16 days at 70°F . Therefore,  temperature d i r e c t l y c o n t r o l s  lamprey egg hatching time and development, but there seems to be only s l i g h t d i f f e r e n c e s i n hatching time and development between the two  species.  The developing  Entosphenus and Lampetra embryos, one  week a f t e r hatching, became more s e n s i t i v e to l i g h t . The  yolk  i n the i n t e s t i n e began to disappear a f t e r the second week from hatching  ( 2 0 - 3 5 days).  The mouth became connected to the.  d i g e s t i v e t r a c t and the b r a n c h i a l pouches formed. The embryos developed  b i l a t e r a l eye spots and the animals began to  burrow, marking the end of .the embryonic stages and the s t a r t of the l a r v a l or ammocoete stage ( P i a v i s I 9 6 0 ) . 4. Burrowing and Free Swimming Action of Larvae Observations on larvae i n the l a b o r a t o r y showed that they began to burrow a f t e r 20 days, but 'in the stream they are already burrowed i n the g r a v e l . In the stream, the larvae leave the gravel a f t e r two or three weeks from hatching, are c a r r i e d downstream by the current and are deposited  i n the f i n e mud  of  pools. Gage ( 1 9 2 8 ) believed that the larvae leave the gravel a f t e r the yolk i s used up, and then migrate downstream to the mud  banks where the microscopic  food supply i s more abundant.  Thomas (1963) shows that there i s a c i r c a d i a n a c t i v i t y rhythm i n ammocoetes kept under 3 d i f f e r e n t day lengths. He found that ammocoete a c t i v i t y occurred during the second hour of darkness. Enequist (1937) showed that some free-swimming a c t i v i t y took place at n i g h t . Kleerekoper et a l . (1962) showed that ammocoetes e x h i b i t a d i u r n a l p e r i o d i c i t y w i t h i n the  mud  109  and at the mud  surface.  5. C o l l e c t i n g Emergent Ammocoetes Below Spawning Nests C o l l e c t i o n s were made i n the Salmon River to determine when newly-hatched larvae leave the gravel and migrate downstream. Table 5 summarizes the r e s u l t s of c o l l e c t i n g larvae i n d i f f e r e n t bottom conditions on the Salmon R i v e r during J u l y 26-28,  1962. Larvae (7-10  mm.)  emerge from the g r a v e l c h i e f l y  during'the dark (22 and 51 larvae were c o l l e c t e d with the Surber sampler; Table 5 ) .  overnight  None were c o l l e c t e d by the  same device during the four d a y l i g h t periods. . Trays f i l l e d with mud  and placed'in the stream i n  various places c o l l e c t e d more l a r v a e during the night than during the day  (Table 5 ) .  This s u b s t a n t i a t e s the r e s u l t s of  the Surber Sampler i n i n d i c a t i n g a d e f i n i t e migration or emergence of r e c e n t l y hatched l a r v a e from the g r a v e l during the dark hours. The t r a y c o l l e c t i o n s seem to i n d i c a t e that the l a r v a e , a f t e r being swept from the g r a v e l i n t o a pool, bury i n t o the mud  bottom throughout the pool area during  darkness,  regardless of the bottom type present. I t appears that some rhythmic  stimulus i n i t i a t e s swimming a c t i v i t y to remove the  l a r v a e from the g r a v e l . The current then c a r r i e s the l a r v a e downstream u n t i l the current i s reduced and the l a r v a e then bury themselves i n t o the bottom. 6. Bottom-type Preference Emergent Ammocoetes A p l a s t i c t r a y with compartments f i l l e d with d i f f e r e n t bottom sediments was  placed i n the Salmon R i v e r  110  Table 5  C o l l e c t i o n of emergent larvae from the Salmon River J u l y , 1962. Temperature 10 to  Pool tray #  Surface current speed  Water depth  Bottom type  19°C. No. of larvaei c o l l e c t e d 600  hr. 1 4 0 0 h r . 2200 hr.  July: 1  .5 f t / s e c: »  11"  3  .2 "  2'  4  .5 "  2'  2  1  1'  .5-1  Modified Surber Sampler  "  3 ft/sec  2'  1.5'  27  28  26  27  26  Mud  2  3  1  0  0  0  Sand  8  5  0  0  0  3  Leaves & mud Rocks & mud Rocks &. mud  5  1  0  2  0  2  21  5  0  0  0  0  0,  0  0  0  0  22*  0  0  0  0  0  Riffle 51 & gravel  27  * a one year larvae was taken i n the Surber sampler.  with no current flowing over the bottom m a t e r i a l s ( F i g . 4 9 ) . Lamprey larvae (8-12 mm.)  were placed i n the h o l d i n g t r a y s  ( F i g . 49E) and the apparatus was allowed to adjust to stream temperature f o r a 30-minute period. I n d i v i d u a l ammocoetes and water were taken from the h o l d i n g trays w i t h a suction tube and the contents were released i n t o the centre of each t r a y . The time taken f o r each ammocoete to burrow i n t o the bottom was recorded by a stop watch and a d d i t i o n a l burrowing behaviour was noted. S i m i l a r procedure was followed w i t h a current of 0.5 f t . / s e c . The observations were made from J u l y 2 6 - 2 8 ,  1962.  Table 6 summarizes the r e s u l t s of the bottom preference by larvae that have r e c e n t l y hatched i n the Salmon River. The  Ill  F i g . 49  Experimental trough used to t e s t the burrowing capacity of small ammocoetes. E- holding t r a y A- mud B- sand C- small g r a v e l D- no cover (measurements i n cm.)  F i g . 50  Experimental trough to t e s t the bottom preference of l a r g e r ammocoetes i n the Salmon R i v e r . A- mud B- sand C- holding t r a y .  112 tanks were placed in'the Salmon River t o t r y to d u p l i c a t e n a t u r a l c o n d i t i o n s , but as the emergence, observations showed, movement of ammocoetes u s u a l l y takes place i n the dark. I t should be borne i n mind that f o r these observations the time to bury would be much shorter i n the l i g h t because the ammocoetes show a photokinesis. .  '  A current greater, than 1 f t . / s e c . c a r r i e d a l l larvae from the tank regardless of the bottom type present. The larvae buried e a s i l y i n t o the mud when no current was present, but the sand and gravel o f f e r e d r e s i s t a n c e to the l a r v a e . They burrowed with great d i f f i c u l t y p a r t i c u l a r l y i n the sand. The bare bottom of the tank and continuous  exposure t o l i g h t  caused the l a r v a e to swim about continuously w i t h t h e i r heads pointed to the bottom and t h e i r t a i l s v i b r a t i n g perpendicular to the bottom. At currents of 0.5 f t . / s e c . larvae  maintained  t h e i r p o s i t i o n and buried t h e i r heads e a s i l y i n the mud, but did not bury the whole body u n t i l l a t e r because of the e f f e c t of current drag on the body. In sand, the l a r v a t r i e d to maintain p o s i t i o n by f o r c i n g the head i n t o the sand, but t h i s was impossible, so the l a r v a was u s u a l l y swept from the tank soon a f t e r l i b e r a t i o n . The gravel bottom i n the current enabled the larvae to maintain p o s i t i o n b e t t e r than i n the sand because they could force t h e i r heads and bodies i n t o the spaces between the. rocks and thus escape the f o r c e of the current. Later they could squeeze between the rocks. They tend to bury themselves more q u i c k l y when the current i s present because the current appears to stimulate the t a i l and thus forces the l a r v a e to burrow completely below the surface.  113 Emergent larvae showed a d e f i n i t e preference f o r mud  bottom  i n a current or i n i t s absence. Larvae had the greatest d i f f i c u l t y burrowing i n t o sand and most were unable to enter t h i s bottom type. Gravel o f f e r e d s h e l t e r f o r the larvae from current and they could burrow slowly i n t o t h i s bottom-type. Table 6  Bottom type preference of emergent larvae from the Salmon R i v e r . Time: s = seconds; m = minutes  Bottom type  Time to bury completely  Mud (.004cc) No current  30s, 10s, 3s  Current of 0.5 f t . / s e c .  5s, 10s.  5s,  Time to bury head only  Time i n which animal swam or was swept from tank  8s.  5s, 15s, 10s.  Sand (.005cc) No current I+m, 5m, 5m, 4m, 3 m• Current of 0.5 f t . / s e c . Small gravel (l-;.5cc) No current Current of 0.5 f t . / s e c . Bare bottom No current Current of 0.5 f t . / s e c .  5s, 15s,  5s.  10s.  5s.  5m, 2m, lm, 4m, Jm. 15s, 10s, 10s.  5s, 5s.  A c t i v e swimming around the tank f o r more than f i v e minutes (5 t r i a l s ) . Swept out of tank i n l e s s than 5 seconds (5 t r i a l s ) .  114 Harden-Jones (1955) performed experiments with glass rods i n an aquarium containing ammocoetes that seem to i n d i c a t e that a thigmotaxic response by the ammocoetes may  play some  r o l e i n bottom preference. S c h o l l (1959) reported that water v e l o c i t y over ammocoete burrows was 2.07  f t . / s e c . This appears  i n c o r r e c t because sediments do, not form at such a v e l o c i t y and can only be found over ammocoete . beds during f l o o d i n g . Thomas (1959) reported, "no ammocoete could burrow i n t o an i n f i n i t e l y s o f t bottom i f i t could not breast the current over i t . " Ammocoetes from the Salmon River l e s s than 40 mm.  can not  penetrate the s o f t e s t bottom with a current over 1 f t . / s e c , while adults of L. p l a n e r i cannot maintain t h e i r p o s i t i o n i n the stream w i t h current above 2 f t . / s e c . Larger Ammocoetes . Ammocoetes (10-15 mm.)  were introduced i n t o the  centre of the middle p a r t i t i o n of an aluminum trough with no current ( F i g . 50). A current of 1 f t . / s e c was introduced i n t o the trough and ammocoetes were introduced 4 inches from the upstream end of the tank. The time and p o s i t i o n f o r each ammoi  coete to bury i n t o the bottom substrate was recorded and F i g . 51). Sand (.005  (Table 7  cc.) and.mud ( l e s s than .004  were used as the bottom types f o r the observations. The vations were recorded on September 15,  cc.) obser-  1962.  With no current in-the trough the small and medium sized larvae buried i n t o the mud  quicker than the l a r g e r larvae.  In the sand substrate the l a r g e larvae buried the quickest and the small l a r v a e had the greatest d i f f i c u l t y i n penetrating the  115 Table 7  Ammocoete b u r i a l r a t e i n the sand and mud In a trough suspended i n the Salmon River (10°C.) Time: s = seconds; m = minutes  Mo current  Time to bury i n the substrata 40-50 mm. larvae  10-15 mm. larvae  2 5-30 mm. larvae  Sand  lm, 2m, 2m, lm, 2m  Ids, 7 s , 7s, 12s, 9 s , 10s, 9 s , 8s, 10s 10s  Mud  9s, 8s  7 s , l i s , 7s, 10s, 8s  8 s , 8 s , 10s,  l i s , 2 8 s , 15s 20s, 14s  Current Ift./sec. 3m, lm  Sand Mud  46s, 16s, 14s, 30s, 17s, 13s, 32s, 14s  14s, 16s, 20s, Ids, 15s  lm, 18s  Time i n which animal swam or was swept from tank by currenl (  Sand  7s, 8 s , 6 s , 7s, 7s, 8s, 7s, 6 s ,  5s, lm, 6 s , 18s, 4 s , 8 s , 7s, 2m, 41s, 20s  10s, 6 s , 10s  7s, 8s, 6 s , 8s,  6s,  6s,  8s,  Mud  8s  7s •  3s  5s  116  sand. However, one and one h a l f months p r i o r to t h i s , the young of the year could not penetrate  the sand. When the current was  introduced only the l a r g e s t larvae could penetrate the sand. Some of the smallest larvae could penetrate the bottom of mud with a current i n the tank but the medium larvae could bury b e t t e r i n the current. The l a r g e r larvae seem to swim some distance before they bury themselves while the smaller larvae seek the bottom immediately on release. Thomas (1963) found s i m i l a r swimming movements i n ammocoetes of the sea lamprey. Macdonald (1957) performed substratum preference  experiments  on sea lamprey larvae using seven d i f f e r e n t bottom types and three s i z e s of ammocoetes. He found that extremely coarsegrained or extremely f i n e - g r a i n e d substrata were seldom used by ammocoetes. The smallest ammocoetes selected the coarsergrained s u b s t r a t a , e s p e c i a l l y the g r a v e l , while the l a r g e r ammocoetes selected the f i n e r - g r a i n e d s u b s t r a t a , e s p e c i a l l y the sand and s i l t . These are contrary observations- to those based on c o l l e c t i o n s taken i n the stream. Macdonald d i d not have a current i n the tank so the smaller larvae probably sank to the bottom and f e l l between the large p a r t i c l e s of the gravels and hence could not seek f u r t h e r f o r a s u i t a b l e bottom. 7. I n t e s t i n e A n a l y s i s of Ammocoetes F i v e ammocoetes d i f f e r i n g i n s i z e (3O-I3O mm.) were selected from each of the A p r i l , June, October, and December c o l l e c t i o n s . A v e n t r a l s l i t was made i n the body w a l l along the length of the body. The i n t e s t i n e was cut p o s t e r i o r t o  117  •  X  •  MUD  !»  X .  x  X  • CURRENT 1 ft/sec. •  • x  •  X  X X  >  SAND  X X  • ••••  • #••• XXXXX xxxxx  F i g . 5 1 ' The p o s i t i o n that the ammocoetes burrowed i n the bottom of a trough with a current of 1 f t . per second at the surface. « - 1 0 - 1 5 mm. l a r v a ©Point of i n t r o d u c t i o n of x - 2 5 - 3 0 mm. l a r v a larva • - 4 0 - 5 0 mm. l a r v a Swam from tank without seeking bottom  the l i v e r and the complete i n t e s t i n e removed. The contents of the i n t e s t i n e were scraped; from the t i s s u e and c o l l e c t e d on a g l a s s s l i d e . The contents were mixed with two drops of water, covered with a cover glass and observed under a microscope ( o i l emersion). An exact q u a n t i t a t i v e estimate of abundance was not determined because the organisms could not. be randomlyd i s t r i b u t e d throughout the f i e l d . However, an estimate of r e l a t i v e abundance was made with 1 0 representing the greatest abundance and 1 representing l e s s than 1 0 organisms i n each i n t e s t i n e . I d e n t i f i c a t i o n of the genera of the organisms was done with the assistance of Dr. J.R. S t e i n of the Department of Biology and Botany, U n i v e r s i t y of B r i t i s h Columbia. Ammocoetes d i f f e r from most l a r v a l f i s h e s i n that they are f i l t e r feeders and have no d i s c r e t e stomach. The organisms found i n the ammocoete i n t e s t i n e are l i s t e d i n Table 8. Diatoms were more than twenty times more prevalent than desmids and other Chlorophyceae. Fine organic m a t e r i a l  118 from decaying plant remains was prevalent i n the f a l l and winter samples. Nematode and mollusc l a r v a e , r a d i o l a r i a n s , and other protozoans were observed on rare occasions. Sand p a r t i c l e s observed i n the i n t e s t i n e of ammocoetes were smaller i n s i z e than the smallest diatom (6, u ) . The l a r g est p a r t i c l e s i n the i n t e s t i n e s were desmids such as Cosmarium (20 u). Table 8  I n t e s t i n e - a n a l y s i s of ammocoetes from the Salmon River Apr. 28  June 10  Oct. 28  Dec. 16  8  10  3  1  R e l a t i v e abundance (Scale 1-10) Diatoms (Cyanophyceae) Navicula Cymbella Synedra Tabellaria Nitzchia Hydrosera Gomphonema . Stephanodiscus Diatoma Melosira Surirella Cocconeis Frustulia Pinnularia  jje  *  #  *  >><  *  *  if  if  if.  if.  if  if  if  if  if.  if  *  >)e  if  3{c  if  if  #  if  >'f  Desmids (Ghlor ophyceae) Closterium AnkistrOdesmus Protococcus Cosmarium Gloeobotrys Scenedesmus Nematode and Clam l a r v e  if  119 Digestion of the contents of the i n t e r i o r of diatoms occurs i n the ammocoete i n t e s t i n e because c h l o r o p l a s t s are. absent from the c e l l s i n the p o s t e r i o r i n t e s t i n e while they are present i n the a n t e r i o r i n t e s t i n e . B a c t e r i a l probably play an important r o l e i n the breakdown of plant debris i n the i n t e s t i n e of the ammocoete. Creaser and Hann (1929) examined the feeding habits .' of Michigan Brook lamprey and found diatoms and desmids present i n a l l the specimens examined. Some protozoans were found on occasion and sand c r y s t a l s and organic m a t e r i a l s were also present. They found that the organisms present i n the i n t e s t ines came from the water, the sediments, and the d e t r i t u s deposited i n the quiet pools. However, none of the ammocoetes obtained any food from the stream bed even though they burrowed i n t o i t . Thus, organic remains and algae were u t i l i z e d and f i l t e r e d from the water f l o w i n g over the ammocoete beds. This food source i s a l s o used by i n s e c t s and molluscs. The use of ammocoete i n t e s t i n e s would seem to be an e f f i c i e n t and thorough method of c o l l e c t i n g and surveying the diatom population of lamprey streams. S c h r o l l (1959) found that when diatoms were a v a i l a b l e they constitued t h e major portion of t h e food i n the i n t e s t i n e and at other seasons of the year more d e t r i t u s was consumed. He found from l a b o r a t o r y a n a l y s i s that diatoms, marl and a c t i v a t e d charcoal were a c t i v e l y ingested, while s t a r c h and wheat f l o u r were l e s s a c t i v e l y ingested. Animal foods as Paramoecium, chopped t u b i c i d s , and f i s h food were taken i n t o  120 the pharynx, .but d i d not appear i n the i n t e s t i n e . The Salmon River and other ammocoetes examined feed almost e x c l u s i v e l y on diatoms. The feeding mechanism of lamprey ammocoetes has been described by Newth (1930) and S c h r o l l (1959). Mucus was secreted by the endostyle and passed a n t e r i o r l y and d o r s a l l y i n l a t e r a l c i l i a t e d strands that are dislodged from grooves by the velum. These strands of mucus unite i n the centre of the pharynx t o form a c o n i c a l net that s e l e c t i v e l y picks up. diatoms and to a l e s s e r extent desmids and d e t r i t u s . The entangled food and mucus pass to the esophagus where c i l i a pass i t to the i n t e s t i n e . Thomas (1963) used f l o u r e s c e n t dyes to show that a continuous current of water was normally drawn i n t o ammocoete burrows. 8. The P r o t e c t i v e Nature of the Lamprey Skin The s k i n of the ammocoete and a d u l t , though l a c k i n g scales and other hard p r o t e c t i v e plates common on f i s h , i s s p e c i a l i z e d to give the animal adequate p r o t e c t i o n . The epidermis of the skin i s covered with a l a y e r of mucus s e c r e t i n g e p i t h e l i a l c e l l s ( F i g 52 e ) . The s l i p p e r y nature of the s k i n and the w r i g g l i n g motion of the lamprey's body makes i t most d i f f i c u l t f o r most animals to grasp the ammocoetes or a d u l t s . Numerous adults have been c o l l e c t e d with jaw" marks j many l i n e s across the body and regenerated t a i l s , the consequences, presumably, of i n j u r i e s i n f l i c t e d by b i r d s , c r a y f i s h , or other predators.. Stomach a n a l y s i s and p r e l i m i n a r y feeding experiments  121 were c a r r i e d out to see i f f i s h would eat ammocoetes. The stomach contents'of 20 coho salmon f r y ( J u l y 27), 5 steelhead t r o u t (July 27), 5 cutthroat t r o u t ( J u l y 27), and 10 redside shiners (Oct. 28) from the Salmon River were caref u l l y examined f o r signs of lamprey ammocoetes. No lamprey ammocoetes were found i n the stomachs of any of the f i s h examined. Hartman (personal communication)  examined "hundreds"  of salmonid stomachs on the Salmon River but found no incidence of lamprey remains. Thomas (1962) found lamprey remains i n brown t r o u t of West Wales to be present i n l e s s than 0.1% of the food and then only during the month of May. However, he found that 5.2% of eels had preyed on ammocoetes (June to September, 1.1% - 2.2% of the food of e e l s ) . C h u r c h i l l (1947) examined 300 t r o u t and 200 sucker stomachs from the Brule River and found no lamprey remains i n the sucker stomachs, but he found remains i n f i v e t r o u t stomachs, but these f i v e were taken by rainbow t r o u t i n e a r l y J u l y when lampreys were abundant on the  spawning g r a v e l . The lamprey remains from the trout stomachs  i n d i c a t e that the adults were i n a spawned-out c o n d i t i o n . In the  post spawning adults the epidermis i s sloughed o f f  (Applegate 1950)  so the remains eaten by the t r o u t p o s s i b l y d i d  not contain the p r o t e c t i v e substance present i n lamprey that i s s p e c i f i c to c e r t a i n f i s h . P r e l i m i n a r y experiments to t e s t whether salmonids would eat ammocoetes and to i d e n t i f y the l o c a t i o n and nature of the  p r o t e c t i v e substance were necessary to an understanding of  the  p r o t e c t i v e mechanism. Feeding experiments were set up to  122  determine whether salmonids would eat lampreys. Ammocoetes ( 3 O - I 3 O mm.)  were introduced, j u s t before  r e g u l a r feeding hours, to the surface of a concrete  hatchery  trough (20 x 20 x 20 f t . ) containing 900 a r t i f i c i a l l y - h a t c h e d coho salmon f r y . Annelid worms the same s i z e as the ammocoetes were introduced to the surface of the tank before and a f t e r the feeding w i t h ammocoetes. The worms were immediately  eaten  by the f i r s t f r y on contact. The ammocoetes were taken i n t o the mouth of the f r y but immediately  spat out. In most  instances an ammocoete that was r e j e c t e d was  immediately  tasted by another f r y and again released. Each ammocoete was tasted by at l e a s t 50 d i f f e r e n t f r y during the 30 minute feeding period. A skinned ammocoete was introduced i n a s i m i l a r manner as the previous specimen, but i t was  always  eaten by the f i r s t f r y making contact with i t . The skin from the skinned specimen was introduced but i t was never eaten although i t went through the same t a s t i n g and r e l e a s i n g procedure as the whole ammocoete. A worm was always eaten by the f r y at the conclusion of each t e s t . The t e s t s were continued for  a f i v e - d a y period. No i n t a c t ammocoetes or ammocoete skins  were eaten during the t e s t , nor were the skinned ammocoetes refused by the f r y . A f t e r the t e s t s a l i v e ammocoete survived i n the tank a f t e r a two-day p e r i o d , despite the  constant  attacks of the f r y . A second experiment was set up using 5 Salmon River coho f r y and 2 cutthroat t r o u t a f t e r holding f o r one week i n a running water glass aquarium. These salmonids were fed the  123  the same combination of lampreys and parts thereof as i n the f i r s t e x p e r i m e n t T h e same preference f o r skinned lampreys and a d i s l i k e f o r whole ammocoetes and the s k i n was  noticed  but by the f o u r t h or f i f t h day the number of attacks was to one or two at each feeding. A f t e r the completion  reduced  of the  t e s t s the f r y were starved f o r two days and very small ammocoetes (2O-3O mm.)  were introduced. Two  ammocoetes were  swallowed but d i d not go through the regular t a s t i n g behaviour that i s common f o r coho f r y . Lamprey eggs were eaten r a p i d l y by salmonids during feeding experiments. Spawning observations i n the Salmon River showed that salmon and t r o u t f r y swam at the rear of lamprey nests and darted forward to eat eggs disturbed from the gravel by the digging and spawning a d u l t s . However, lamprey eggs are u s u a l l y buried and covered by sand i n the nest and  digging  proceeds upstream from the deposited eggs so few eggs are a c t u a l l y disturbed by f u r t h e r digging. Young of the year and f i r s t year ammocoetes were eaten when fed to f r y during d a y l i g h t hours i n the Salmon River. Emergent ammocoetes were eaten h a l f the time by salmonid f r y i n a l a b o r a t o r y feeding experiment. Frozen brine shrimp was introduced before and a f t e r each feeding. From these observations i t appears that salmonid f r y w i l l u s u a l l y t a s t e l a r g e r ammocoetes and objects before swallowing, but small ammocoetes are o c c a s i o n a l l y swallowed without t a s t i n g . Skin sections from the smallest ammocoetes revealed a decrease i n the number of granular c e l l s . This would account f o r t h e i r being eaten by  124 the f r y o c c a s i o n a l l y while l a r g e r ammocoetes that contain more granular c e l l s are not eaten. Small ammocoetes remain buried i n the bottom sediments during d a y l i g h t and escape predation by f i s h . They are s u s c e p t i b l e to predation during f l o o d i n g and during t h e i r d a i l y c i r c a d i a n movements from the bottom, but they are probably protected by the t o x i c s e c r e t i o n from the granular c e l l s at t h i s time. 'Stomach a n a l y s i s from the Salmon River during emergence i n d i c a t e s that emergent ammocoetes are not eaten by f r y . The emergent ammocoetes may not be seen or smelled by the f r y when they emerge and bury during the dark. Ten redside s h i n e r s , 10 s t i c k l e b a c k s , and 5 spiny v  s c u l p i n s from the Salmon River were kept i n aerated room temperature tanks and f e d l i v e ammocoetes on three occasions. The s c u l p i n s ate small ammocoetes on one occasion, but on two occasions they t a s t e d and released l a r g e r ammocoetes. The shiners and s t i c k l e b a c k s never ate the ammocoetes but they did eat skinned ammocoetes on two occasions. One  squawfish  (Ptychocheilus oregonense)was f e d l i v e ammocoetes and ammocoete s k i n on t e n d i f f e r e n t occasions. The ammocoetes and s k i n were immediately  eaten on a l l occasions.  P f e i f f e r (personal communication) fed ammocoetes and adults t o b l i n d cave f i s h (Anoptichthys .jordani) and adult rainbow t r o u t . The cave f i s h ate the lampreys while the rainbow t r o u t d i d not.- Perlmutter (1951) kept ammocoetes and eels i n an aquarium and recorded that the eels burrowed i n t o the mud of the aquarium and ate some of the ammocoetes.  125  The s k i n of a Lampetra ammocoete was preserved i n Bouin's f i x a t i v e and s t a i n e d w i t h Azan ( F i g . 52). The s i t e of the p r o t e c t i v e s e c r e t i o n appears to be i n the granular (g) or club c e l l s (c) of the epidermis. Pores (p) connect the granular and club c e l l s t o the surface, and the d i s t a s t e f u l substance i s discharged and d i s t r i b u t e d along the e p i t h l i u m when the s k i n i s compressed or b i t t e n . Sections of ammocoete s k i n preserved i n Bouin and s t a i n e d with P. A. S. and T o l u i d i n e blue revealed that mucus was present i n the uppermost l a y e r of the epidermis and covered the epidermis. No mucus was present i n the granular c e l l and club c e l l s . Club c e l l s and granular c e l l s are very s i m i l a r i n s t r u c t u r e and chemical composition. P f e i f f e r (I960) suspected that the club c e l l s move to the surface of the epidermis and become granular c e l l s . The author and a co-worker t a s t e d l i v e ammocoetes on numerous occasions and found that the skin was not d i s t a s t e f u l when the ammocoete covered with mucus was placed i n the mouth and over the tongue. However, when the ammocoete was pressed between the t e e t h and then placed on the tongue a b i t t e r and unpleasant t a s t formed i n the mouth. This substantiated that the d i s t a s t e f u l substance i n the s k i n does not come from the mucus but i s probably f o r c e d from the skin when the s k i n i s compressed or b i t t e n . Thus, f i s h that tend to swallow t h e i r prey without t a s t i n g i t would not respond to the p r o t e c t i v e substance i n the s k i n , but those f i s h that t a s t e and hold t h e i r prey i n the mouth before swallowing would react to the s k i n s e c r e t i o n and release the lamprey.  126  Guibe' (1958) reported that the skin of lampreys was probably poisonous but he did not present any evidence to validate the statement. The above experiments show that ammocoetes are probably protected from predation by salmonid and other fish in the Salmon River, by secretion from special cells in the skin.  Fig. 52. Epidermis of Lampetra planeri ammocoete (110 mm.) from the Salmon River, Dec. 28, 1962. (Bouin, Azan x 500) C - club cells; g = granular cells; p= pore of a granular cell; e = mucus secreting epidermal cells. 9. Distribution of Ammocoetes within the Stream_ Analysis of monthly collections of ammocoetes made from many bottom types throughout the Salmon River in 1 9 6 0 - 6 1  127 indicated  a s e l e c t i o n f o r p a r t i c u l a r bottom t y p e s and p o s i t i o n s  i n t h e stream by d i f f e r e n t s i z e d ammocoetes. I n 1962 v a r i o u s h a b i t a t s and ammocoete beds were sampled t o see i f t h e r e was any r e l a t i o n between s i z e and s u b s t r a t e p r e f e r e n c e  F i g . 53  ( F i g . 53)-  Large p o o l where ammocoetes a r e d e p o s i t e d , Salmon R i v e r , s t a t i o n 1. x - l a r g e r ammocoetes; o - s m a l l e r ammocoetes. L a r g e permanent ammocoete beds at s t a t i o n 1 and 4  ( F i g . 3) were sampled. F i g . 54 shows t h e d i s t r i b u t i o n o f ammocoete beds i n r e l a t i o n t o t h e spawning n e s t s and c u r r e n t at s t a t i o n 1. Ammocoete beds A, B, and 0 were r e l a t i v e l y permanent d u r i n g t h e s t u d y , w h i l e bed D was formed d u r i n g t h e summer and beds E and F were formed d u r i n g t h e w i n t e r months or a f t e r h i g h f l o w c o n d i t i o n s . Bed F d r i e d up d u r i n g t h e summer. Ammocoete c o l l e c t i o n s from t h e p o o l s o f s t a t i o n 1 and 4 from t h e Salmon R i v e r ( F i g . 57 t o 59) show t h a t t h e r e i s a s i g n i f i c a n t d i f f e r e n c e i n s i z e o f ammocoetes i n t h e d i f f e r e n t  128  FIG.54. AMMOCOETE BEDS AND SPAWNING NESTS STATION I SALMON RIVER.  129  FIG.55. STATION 4  SALMON RIVER  FIG.56. STATION I POOL  SALMON  RIVER  131  bottom types. C o l l e c t i o n s from the mud and s i l t near the bank (Fig. 57B,  55B and 56B) 57C,  58B,  are represented by the histograms (Figures  and 59A).  F i r s t and second year classes pre-  dominate, i n the c o l l e c t i o n s . Ammocoetes from the sand and leaves from the deeper regions of the pool bottom ( F i g . 5 5 A and 5 6 A ) are represented by the histograms i n Figures 57A,  58A,  58D,  59B, and  59C  These histograms show.a s i g n i f i c a n t d i f f e r e n c e from the mud bottom h a b i t a t . Second or o l d e r year c l a s s e s predominate while the young of the year and f i r s t year l a r v a e are l e s s abundant. Fig.  59B compared to F i g . 59D shows that few of the young of  the year and f i r s t year ammocoetes remained i n the sand of bed A ( F i g . 56) during the w i n t e r , they were present i n September. Flooding p o s s i b l y removed the smaller ammocoetes while the l a r g e r ammocoetes remained permanent r e s i d e n t s . The ammocoete bed C ( F i g . 56)  composed of sand and  a very t h i n t r a n s i e n t l a y e r of surface mud contained the same s i z e ammocoetes as those located i n the f i n e mud and  silt.  The above r e s u l t s c l e a r l y show that bottom composition, l a r g e l y determined by current flow, i n f l u e n c e s the s i z e d i s t r i b u t i o n of the ammocoetes i n the Salmon River. The v a r i a t i o n of s i z e classes between ammocoete beds shows the need f o r sampling throughout the bottom habitat at various times of the year to obtain an unbiased sample of the population. E l e c t r i c shockers have been used to c o l l e c t ammocoetes i n recent years but t h i s does not produce good c o l l e c t ions of the smaller ammocoetes ( C h u r c h i l l 1 9 4 7 ) , and scooping  LO  ©STATION 4 S A N D , L E A V E S - BOTTOM, POOL  A  LU g e n  ©STATION 4 MUD, L E A V E S •> BANK , POOL  a: <  _io LL O  LO  cn UJ  m z  SALMON  ZD L O  LO  ro  R.  FEB23/62 ©STATION 3 MUD, L E A V E S -  BANK  A  20  40  60  LENGTH  IN  80  100  MILLIMETRES  120  140  FIG. 57. LENGTH - FREQUENCY DISTRIBUTION OF L. PLANERI AMMOCOETES IN DIFFERENT SALMON RIVER ON FEBRUARY 23,1962.  HABITATS  OF THE  20  40 LENGTH  IN  60 MM  80  DO  FIG. 58. LENGTH-FREQUENCY DIAGRAMS OF LAMPETRA IN DIFFERENT HABITATS OF THE SALMON , RIVER SEPT. 9,1962.  140  LENGTH  IN  MM  FIG.5a LENGTH-FREQUENCY DIAGRAMS OF L A M P E T R A IN DIFFERENT OF THE SALMON RIVER (STATION I).  HABITATS  13 5  from the substrate produced few l a r g e r ammocoetes (Schultz 1930). A combination  of c o l l e c t i n g methods seems necessary to c o l l e c t  a l l age c l a s s e s . 10. R e l a t i v e Abundance of Ammocoetes An estimate of r e l a t i v e abundance of ammocoetes was obtained by counting the animals i n a constant bottom area and quantity of sediment scooped from the ammocoete beds ( F i g . 1 0 ) . The greatest concentration of ammocoetes wa';s found i n the sand and l e a f substrate of deep pools ( F i g . 60 a, f , g ) . Mud areas did not contain as many ammocoetes as the sand and l e a f areas. However, when a square root transformation was performed on the data and a t - t e s t performed no s i g n i f i c a n t d i f f e r e n c e was evident. Greater numbers of ammocoetes i n the sand are probably due to the greater numbers of year c l a s s e s present. Temporary winter ammocoete beds contained a s i g n i f i c a n t l y smaller conc e n t r a t i o n of animals than other beds. Flooding conditions on June 3 produced a great reduction i n d i v e r s i t y , but pre-flood d i v e r s i t i e s were a t t a i n e d by June 10 when sediments had again accumulated when flow decreased. Thomas (1963) found.that  sea lamprey ammocoetes were  most abundant where the current was very slow and the bottom was very s o f t . He found that the population density of ammocoetes was p r o p o r t i o n a l to bottom hardness and water v e l o c i t y . In the absence of good bottom c o n d i t i o n s , ammocoetes were able to f i n d s h e l t e r i n almost a l l n a t u r a l l y - o c c u r r i n g bottom m a t e r i a l s . The Salmon River ammocoetes show the greatest conc e n t r a t i o n s i n the harder sand and l e a f bottoms of pools  a.  DEC. 16/62 (5)  ©  b. DEC. 16/62  c. DEC. 16/62  l  o  ©  I  SAND AND LEAVES MUD P?773 TEMPORARY BED f~[~l MEAN NUMBER  ,©  ®  d. JUNE 3 / 6 2 (FLOODING)  AMMOCOETE BEDS FROM FIGURE 54  0  a. JUNE 3 / 6 2 (FLOODING)  •..•>..f^rn.Vjt::V:?|  ©  f. JUNE 10/62  ©  g. SEPT. 9 / 6 2  2  4 6 8 10 12 14 16 NUMBER OF AMMOCOETES PER STANDARD  18 20 SCOOP  22  24  26  28  30  FIG. 60. CONCENTRATION OF AMMOCOETES FROM DIFFERENT BOTTOM HABITATS IN THE SALMON RIVER • STATION I.  137  .  during the periods of reduced flow. The p o s i t i o n s of the sand' and l e a f beds ( F i g . 56A) near the c e n t r a l current of the stream would c o l l e c t more ammocoetes than the beds at the s i d e of the stream at low flow c o n d i t i o n s . The smaller specimens would have d i f f i c u l t y penetrating the sand but the spaces between the leaves would enable the animals to enter the bottom. However, i t appears that the smaller l a r v a e are then washed from the sand beds or swim to s e t t l e permanently i n the mud at the edge of the stream. The l a r g e r ammocoetes can remain i n the sand beds permanently. Winter c o l l e c t i o n s of ammocoetes from the Salmon River at various depths showed the greatest concentration i n the shallow water near the bank, but summer c o l l e c t i o n s showed the opposite. Therefore, the ammocoetes seemed t o c o l l e c t near the shore i n shallow water during the winter because increased current i n deeper water erodes the beds and prevents penetrat i o n of the substrate whereas s i l t accumulation and reduced current occurs at the shore. In the summer the sand and s i l t beds ( F i g . 55 and 56)  i n the deeper water (4 to 6 f e e t )  contained the greatest concentration of ammocoetes. Thomas (1963) also found depth of l i t t l e  s i g n i f i c a n c e because water  v e l o c i t y determines s i l t d e p o s i t i o n and p o s i t i o n of ammocoete beds. E a r l y workers u s u a l l y recorded that ammocoetes preferred shallow water but t h i s d i s t r i b u t i o n was p o s s i b l y due t o s i l t d e p o s i t i o n at the bank of streams due to a f a l l i n current v e l o c i t y r a t h e r than depth d i s t r i b u t i o n .  138 11. Burrowing; Behaviour of Ammocoetes Knowledge of how ammocoetes burrow i n t o a substrate o f f e r s some explanation of the substrate they s e l e c t and t h e i r r e l a t i v e abundance i n each substrate. Gage (1893) observed burrowing ammocoetes i n glass containers and recorded  two  stages. F i r s t the animal stands v e r t i c a l l y on i t s head and makes vigorous swimming movements while t w i s t i n g the o r a l hood from side to s i d e . These motions continue u n t i l the g i l l  slits  are buried. The second stage involves the buried s e c t i o n which parts the sand ahead of the l a r v a w i t h the s t i f f o r a l hood and p u l l s i t s body i n t o the sand to form a U-shaped burrow. The Salmon River ammocoetes buried i n the same manner as described by Gage. The behaviour of an ammocoete l i b e r a t e d i n an aquarium or stream was described by Reighard and Cummins (1916). The ammocoete " swims a short distance, then erects, the body almost v e r t i c a l l y , head downward, and burrows with r a p i d v i b r a t o r y movement. I t does not continue s t r a i g h t down, but turns h o r i z o n t a l l y , then upward, forming a burrow i n the shape of a f l a t t e n e d U. The d o r s a l surface of the body i s kept uppermost throughout t h i s process." Salmon River ammocoetes observed i n experimental  troughs behaved s i m i l a r l y , but small  ammocoetes had not completely buried t h e i r t a i l s on many occasions u n t i l f i v e minutes a f t e r they buried the pharynx. Sawyer (1959) observed ammocoetes burrowing i n t o a wad  of cotton and found the o r a l hood was the main digging  organ. The body was  held r i g i d as the muscular movements pushed  139 the animal i n t o the substrate. The o r a l hood was  contracted  to a point and moved from side to side to f i n d the path of l e a s t r e s i s t a n c e . When the head and pharyngial basket were pushed forward, as f a r as p o s s i b l e by the swimming and w i g g l i n g motion, the o r a l hood was as the body was  f l a r e d out and served as an anchor  p u l l e d up from behind. The process was  repeated  u n t i l the ammocoetes were covered i n the bottom and a Ushaped tube had formed with the head end open to the surface, of the substrate. Sawyer's observations help to explain the d i f f i c u l t y f o r small ammocoetes from the Salmon River to penetrate hard bottoms as sand, but show a preference f o r mud  and s i l t bottoms. Applegate (1950) showed that the depth of the burrows  was  p r o p o r t i o n a l to the l a r v a ' s length with the l a r g e s t l a r v a  (100-160 mm.)  occupying a burrow 125 mm.  i n depth. Burrows i n  sand covered with muck were constructed e n t i r e l y i n the muck. This d i s l i k e f o r sand beneath s o f t e r bottoms r e s t r i c t e d them to the surface l a y e r s i n the Salmon River. Due to the depth of burrow c o n s t r u c t i o n the l a r g e r ammocoetes are l i k e l y to be unaffected by f l o o d i n g while the smaller specimens are l i k e l y to be c a r r i e d downstream by the current, which i s what occurred i n the Salmon River (Figures 57, 59, and 6 0 ) . The absence of small ammocoetes from sand beds i n the Salmon River may  be due to t h e i r d i f f i c u l t y to f o r c e the  sharp sand grains apart and t h e i r l a c k of s u f f i c i e n t swimming speed to maintain a p o s i t i o n i n current. However, sand i n t e r spaced w i t h leaves or c o n t a i n i n g a top l a y e r of mud  offered  140 refuge from the current. Ammocoetes from the Salmon River seem to need contact w i t h the bottom or t o have t h e i r bodies touching a substrate. Harden-Jones (1955) showed a thigmotaxic response of L. p l a n e r i ammocoetes i n the l a b o r a t o r y . A photokinesis response (Young 1931) also helps t o keep them buried i n the mud of stream bottoms. As the animals increase i n age, t h e i r preference f o r bottom contact and darkness decreases. Leach (1940) found that transforming brook lamprey g r a d u a l l y l o s t t h e i r preference f o r the bottom. 12. Movement of Ammocoetes i n Burrows The bottom of a 5-gallon aquarium was. f i l l e d with 3 inches of mud from an ammocoete pool of the Salmon River on September 28, 1962. Twenty ammocoetes (15-50 mm.) were introduced i n t o the mud. The bottom of the tank was marked o f f i n t o 16 equal parts by a g r i d f i t t e d over the top of the tank so that the exact p o s i t i o n of each lamprey burrow could be recorded. Morning and evening observations were taken from October 3 to 5 and d a i l y observations were made from November 6 t o December 31. One of the sections was randomly chosen as a c o n t r o l square and contained no lampreys. This square was p a r t i t i o n e d o f f with nylon c l o t h so that wdrm and i n s e c t burrows could be d i f f e r e n t i a t e d ' f r o m those of ammocoetes. Over a 24-hour period never more than 20% of the burrows remained unchanged. A l l burrows had s h i f t e d p o s i t i o n over a 48-hour period. New burrows were formed during the day and n i g h t . No ammocoetes were seen outside t h e i r burrows at  141  any time. Thomas  (1963)  observed s i m i l a r r e s u l t s f o r the .  sea lamprey, but he found no evidence of c i r c a d i a n rhythm of burrow c o n s t r u c t i o n or l e a v i n g the burrow during the dark. He took photographs of the ammocoete burrow mouths but found no i n d i v i d u a l s v i s i b l e during the darkness. He found a c i r c a d i a n rhythm of free-swimming a c t i v i t y present i n the ammocoetes during the dark. Therefore a large proportion of the population apparently leave t h e i r burrows during the dark but t h i s was  not  recorded by the f i l m . Thomas  (1963)  c o l l e c t e d ammocoetes i n weirs at  dawn and dusk and showed that migration occurs almost e x c l u s i v e l y downstream and at n i g h t . He c o r r e l a t e d t h i s migration d i r e c t l y with water temperature and water flow. M i g r a t i o n of ammocoetes would account f o r the s h i f t of age composition  and  concentration w i t h i n the ammocoete beds of the Salmon R i v e r . A spawning migration of adult lamprey from the region below s t a t i o n 1 to above s t a t i o n 1 i s suspected because the ammocoetes moving to new burrows are d i s p l a c e d downstream, but they must r e t u r n to g r a v e l areas to spawn i n the s p r i n g . 13.  Growth of Ammocoetes The lamprey.of B r i t i s h Columbia and Washington are  c h a r a c t e r i z e d by a p a r t i c u l a r l y long spawning period ( A p r i l to J u l y ) . This makes determination of age by i d e n t i f i c a t i o n of year c l a s s e s from length-frequency  data very d i f f i c u l t .  The  modes of the f a s t growing i n d i v i d u a l s tend to overlap those of the slow growing animals. The modes of the f i r s t two age groups from the  142  Salmon River ( young of the year and one year larvae) can be e a s i l y d i s t i n g u i s h e d i n most c o l l e c t i o n s (Figures 6 l and  62).  The y e a r l y growth f o r the f i r s t two year classes was p l o t t e d from the p o s i t i o n of the modes at various times throughout the year and two curves were f i t t e d by eye ( F i g . 6 3 ) .  These  growth curves r e v e a l a period of slowing down or cessation of growth during the winter months. This, was also suspected by Schultz (1930) f o r L. p l a n e r i i n Washington State. The young of the year i n the Salmon River grow r a p i d l y from June to  :  November while the f i r s t year larvae grow most r a p i d l y from A p r i l to August. I n t e s t i n e a n a l y s i s of l a r g e r ammocoetes reveals that the main food supply (diatoms) i s rather scarce i n the winter months, abundant i n the spring and summer, and r a t h e r scarce i n the l a t e f a l l . The period of greatest growth by the ammocoetes i s most l i k e l y dependent upon density of diatoms i n the stream. A comparison of the growth of p o s i t i o n s of modes i n the Salmon River ( F i g . 62) with that of other r i v e r systems (Fig.  6l)  reveals a great s i m i l a r i t y of modes f o r the  first  year c l a s s e s . This suggests that most Lower Fraser V a l l e y streams and Vancouver Island streams produce ammocoetes that have the same growth r a t e s . The preference f o r bottom type as i n the Salmon River was  observed i n the streams i n F i g . 6 l .  Smaller year classes were found i n the mud  and sand bottoms  while the l a r g e r ammocoetes occupied the v a r i a b l e bottom of sand, leaves, and mud  i n the pool areas.  The histograms of the Salmon River ammocoete c o l l e c t i o n s ( F i g . 62)  show a great v a r i a b i l i t y i n the year c l a s s  143 TSOLUM RIVER AUG. 29 1961 VARIABLE BOTTOM  20 30 40 50 LENGTH IN MM FIG. 61 LENGTH-FREQUENCY DISTRIBUTION OF CERTAIN STREAMS IN BRITISH COLUMBIA .  AMMOCOETES FROM  144 A  62 Length-frequency d i s t r i b u t i o n of ammocoetes from the Salmon R i v e r , 1960-1963.  144 B  A 1962 • 1961 O I960  I  — ,  1————i  JUNE  JULY  1  AUG  r—  SEPT  OCT  1  1  NOV  »  DEC  ~  JAN  1  •  FEB  "  1  ~~*  MAR. APR. MAY  FIG. 63.GROWTH OF A M M O C O E T E S ( L . planeri ) IN THE S A L M O N RIVER DURING THE Y E A R I960- 62 ( c u r v e f i t t e d by e y e )  146 as c o l l e c t e d at d i f f e r e n t times of the year and i n d i f f e r e n t h a b i t a t s . Sampling a v a r i e t y of h a b i t a t s produced a v a r i e t y of year classes and represented  the population, but samples of  a r e s t r i c t e d area u s u a l l y revealed only one or two year c l a s s e s . 14. £. t r i d e n t a t u s Ammocoetes from the Thompson and N i c o l a River C o l l e c t i o n s of E. t r i d e n t a t u s larvae were taken from t h i s r i v e r system on three occasions f o r comparison w i t h the mixed population  (Lampetra and Entosphenus) from the Salmon  R i v e r . The August 19, 1961  c o l l e c t i o n was  taken from three  •different h a b i t a t s and l o c a t i o n s on the r i v e r system to compare with s i m i l a r h a b i t a t s i n the Salmon R i v e r . In the N i c o l a and Thompson Rivers the stream bed i s c h a r a c t e r i z e d by r i f f l e and pool areas. The r i f f l e areas contain l a r g e boulders and l a r g e r g r a v e l s i z e t h a n that present i n the Salmon R i v e r . The pool areas of the N i c o l a and Thompson Rivers do not contain the quantity of s i l t and plant debris that i s common i n the Salmon River. The water discharge  and  drainage basin i s much l a r g e r f o r the Thompson and N i c o l a system. The  cold winter conditions may  reduce or decrease  growth f o r the ammocoetes i n the i n t e r i o r r i v e r s . The histograms i n F i g . 6 4 show that the Entosphenus l a r v a e seem to e x h i b i t s i m i l a r preference  f o r bottom type as  the Salmon River population. The smaller larvae (Camford S t a t i o n ) were c o l l e c t e d i n a predominantly mud  bottom while  the l a r g e r ammocoetes were c o l l e c t e d i n the sand and leaves of pools  (Dot s t a t i o n ) of the N i c o l a River and Spenser's Bridge  147  LENGTH  IN  MILLIMETRES  FIG.64. L E N G T H - F R E Q U E N C Y DIAGRAM E N T O S P H E N U S L A R V A E , A U G . 19/61  OF  148 on the Thompson River. Figure 6 4 i n d i c a t e s an increase i n the number of smaller l a r v a e as the c o l l e c t i o n s were taken f a r t h e r up the N i c o l a R i v e r . This could i n d i c a t e a spawning above M e r r i t t and a migration downstream by the l a r v a e . However, l a t e r c o l l e c t i o n s i n d i c a t e l a r g e ammocoetes i n the upper r i v e r as w e l l . Thus habit s e l e c t i o n by the ammocoetes and sampling v a r i a t i o n , as w e l l as some downstream migration would' be p o s s i b l e explanations f o r t h i s d i s t r i b u t i o n . The lengthfrequency histograms ( F i g . 65) show the data c o l l e c t e d and means f o r each age c l a s s can be followed, throughout the c o l lections. L. p l a n e r i and E. t r i d e n t a t u s e x h i b i t s i m i l a r l a r v a l requirements and general stream behaviour.  E. t r i d e n t a t u s  possess a f a s t e r growth rate and a possible shorter l a r v a l period than L. p l a n e r i . The i n t e s t i n e s of 10 ammocoetes from 1  the N i c o l a River i n A p r i l and August revealed a greater abundance of diatoms than the Salmon River population. Cymbella was a diatom that was p a r t i c u l a r l y dominant i n most i n t e s t i n e s . The increased diatom intake by the ammocoetes may account f o r the f a s t e r growth r a t e of Entosphenus i n the Thompson and N i c o l a Rivers than the mixed population (predominantly  Lampetra)  of the Salmon R i v e r . 15.  Age Determination  and Growth Curves of Ammocoetes  The separation of the year classes was determined using the p r o b a b i l i t y paper graphic method of polymodal frequency a n a l y s i s devised by Harding  (1949) and extended by  Cassie (1954). Two of the l a r g e s t c o l l e c t i o n s of L. p l a n e r i  149  THOMPSON RIVER F E B . 24/62  NICOLA RIVER AUG. 2 / 8 2 10-  LU  < > or  NICOLA and THOMPSON RIVER AUG. 19/6 1  <Uo-  _j  QC 111 20  CD Z  13 10 2 10  20  30  LENGTH  40  IN  50  60  70  80  90  100  110  MILLIMETRES  FIG.65. L E N G T H - F R E Q U E N C Y OF E N T O S P H E N U S L A R V A E FROM THE NICOLA and THOMPSON R.  120  150  (10  percent E. t r i d e n t a t u s ) from the Salmon River ( F i g . 66  and 67)  containing the greatest number of year classes were  selected f o r the p r o b a b i l i t y paper a n a l y s i s . The two c o l l e c t i o n s of E. t r i d e n t a t u s Rivers ( F i g . 68 and 69)  large  from the N i c o l a and Thompson  were used to separate the year c l a s s e s .  A summary of the p r o b a b i l i t y paper a n a l y s i s i s presented i n Table 9 which shows the mean, percent of the c o l l e c t i o n ,  and  standard d e v i a t i o n f o r each age c l a s s . The two c o l l e c t i o n s of each species when p l o t t e d o f f e r e d a check f o r p i c k i n g the correct i n f l e c t i o n p o i n t s . The growth curve f o r each species was  drawn by  eye from the mean of each age class' ( F i g . 70 and 71)  and  curves of the two species are presented i n F i g . 72.  The  i n f l e c t i o n points were d i f f i c u l t to pick out i n F i g . 69  the  as  two minor nodes could be accepted instead of a s i n g l e age 3 node. I f the age 3 minor nodes were p l o t t e d as i n F i g . 71 then the growth curve would not correspond to the curve of the other sample ( F i g . 68).  The major age three node places  the  curve i n agreement with the other sample of E. t r i d e n t a t u s . The  i n f l e c t i o n points f o r both L. p l a n e r i samples showed good  agreement when the growth curve was  fitted.,  A comparison of the growth of L. p l a n e r i and  E.  t r i d e n t a t u s shows both curves to be very s i m i l a r . A s l i g h t l y more r a p i d rate of growth occurred i n E. t r i d e n t a t u s ammocoetes. This could be due to d i f f e r e n c e s i n n u t r i t i o n . E. t r i d e n t a t u s appears to decrease growth i n the older larvae stages as i n d i c a t e d by the growth curve, but t h i s i s p o s s i b l y due  to  STANDARD DEVIATION  PERCENT  CONFIDENCE LIMITS,P*05.  84.13  10 20 30 40 50 60 70 80 CUMULATIVE FREQUENCY (% ) FIG. 67. SEPARATION OF POLYMODAL FREQUENCY DISTRIBUTIONS OF PROBABILITY PAPER (SALMON RIVER, F E B . 2 3 , 1962 )  90 L. PLANERI  99 AMMOCOETES  USING  STANDARD DEVIATION  CONFIDENCE LIMITS.P=05.  PERCENT  10 20 30 40 50 60 70 80 CUMULATIVE FREQUENCY ( V . ) FIG. 67. SEPARATION OF POLYMODAL FREQUENCY DISTRIBUTIONS OF PROBABILITY PAPER (SALMON RIVER, F E B . 2 3 , 1962 )  90  99  L. PLANERI AMMOCOETES  USING  FIG. 68. SEPARATION OF POLYMODAL FREQUENCY DISTRIBUTIONS OF E . TRIDENTATUS PROBABILITY PAPER ( THOMPSON AND NICOLA RIVER , AUG. 19 , 1961 )  AMMOCOETES  USfNG  15 ' 1  '  1  10 20 CUMULATIVE  1  •  —I  •  i  30 40 50 60 70 FREQUENCY ( '/» )  l  80  1  |  90  FIG. 69. SEPARATION OF POLYMODAL FREQUENCY DISTRIBUTIONS OF PROBABILITY PAPER ( NICOLA RIVER, AUG. 2 , 1962 )  |  I  10 5 I  L.  99  E. TRIDENTATUS  AMMOCOETES  USING  155 Table 9  Summary o f p r o b a b i l i t y paper a n a l y s i s o f two c o l l e c t i o n s of L. p l a n e r i and E.  tridentatus.  L. p l a n e r i Date  Age  Sept. 9/62  0 1 2 3 4 - 5  Percent 39 20 17 14 6 5  Mean 17.5 36 47.5 58 72.5 95.5  2.4 4.17 3-76 3.6 4.14 9.92  22 40 53 66.5 84 110.5  2.96 5.16 5.88 5.54 8.6 9.55  0 1 2 3 4 5  32 40 9 5.6 4« 4 9  Aug. 2/62  0 1 2 3a 3 3b 4 5  3 16 16 . 18 35 17 19 11  9.8 . 35.5 44.5 55.5 60 65 76.5 91  Aug. 19/61  0 1 2 3 4 5  36.6 20.4 14 13 10 6  17.5 39 52.5 67.5 78.5 97  Feb. 23/62  Standard D e v i a t i o n  E. t r i d e n t a t u s Date 1.29 2.31 5.5 3.6 5.4 2.85 5.27 6.3 2.37 5.5 5.1 5.1 3.1 10.1  156  FIG.70.GROWTH C U R V E OF L A M P E T R A FROM THE SALMON RIVER  PLANERI  157  i  i  I 2 AGE IN Y E A R S .  i  i  i  3  4  5  i  6  FIG. 71. G R O W T H C U R V E OF E N T O S P H E N U S T R I D E N T A T U S NICOLA AND T H O M P S O N RIVER  158  FIG.72. GROWTH C U R V E S OF BRITISH COLUMBIA L A M P R E Y S (NICOLA AND S A L M O N RIVER )  159 d i f f i c u l t i e s i n aging the older l a r v a e . The 10 percent of E. t r i d e n t a t u s mixed with the L . p l a n e r i population of the Salmon River would seem to have l i t t l e or no effect on the a n a l y s i s of growth and age determination because of the s i m i l a r i t y of growth between the two species. The average l i f e cycle of L . p l a n e r i appears to be 6 years or more and that of E. t r i d e n t a t u s  i s 7 years or  more. No allowance was made f o r p o s s i b l e reduction i n length before transformation, f o r premature i n d i v i d u a l s , or f o r the presence of a r e s t p e r i o d . Schultz (1930) i n Washington State and Knowles (19.41) i n England ascertained the l a r v a l l i f e of L . p l a n e r i to be three years. Zanandrea (1951 and 1954) and MacDonald (1959( c a l c u l a t e d the l a r v a l l i f e to be four and one-half years for the same species i n Europe. Hardisty (1961) estimated the average l a r v a l period of L . p l a n e r i i n England at about f i v e and one-half years from l a r g e samples c o l l e c t e d throughout each year from 1940 to I960 i n one r i v e r system. He determined that ammocoetes grow more r a p i d l y during the f i r s t year and i n the f i n a l growth season before transformation, but at transformation he found a reduction i n l e n g t h . He estimated that the annual m o r t a l i t y rate of ammocoetes was . f a i r l y uniform throughout the l a r v a l p e r i o d . The growth curve of B r i t i s h Columbia lampreys agrees with the shape of H a r d i s t y ' s lamprey curves but both do not represent the a c t u a l growth because of l a c k of knowledge of the biology of the l a s t few years of l a r v a l  life.  The percentage of each year c l a s s present i n each  160 c o l l e c t i o n i s not constant i n the two samples analysed f o r each species (Table 9)• The means of the year classes show a very good f i t f o r the growth curve ( F i g . 70 and 71). The standard d e v i a t i o n f o r the f i r s t " to t h i r d age classes show, remarkable consistency but v a r i a t i o n s increased with the l a r g e r age c l a s s e s . This i s p o s s i b l y due to a r e s t period, sexual d i f f e r e n c e s i n growth, or i n d i v i d u a l d i f f e r e n c e s i n growth. The growth curves of the ammocoetes f o r the two species of lampreys ( F i g . 72) are representive of ammocoete growth up to ages 3 or 4, but then the curve becomes i n c o n s i s tent with the biology of- the l a r g e r l a r v a e . The accumulated v a r i a b l e s o f i n d i v i d u a l growth, length d i f f e r e n c e s with sex, p o s s i b l e reduction i n length before transformation and the presence of a r e s t period a l l tend t o make length  frequency  a n a l y s i s inadequate f o r the l a r g e r s i z e d l a r v a e . Growing marked ammocoetes i n a stream environment from age two or three would be d e s i r a b l e . I f l o c a l ammocoetes possess a r e s t period, then the growth curve up to transformation would take on the shape of the von B e r t a l a n f f y growth curve f o r length. L.  t  = L o c ( 1-e  k(t-t) 0  )  L = asymptote of the growth curve t  Q  = age at length zero, i f the animal had grown according to the formula over the whole of i t s l i f e ,  k = slope t = age  161 A l i n e of best f i t could be c a l c u l a t e d f o r the B r i t i s h Columbia lamprey growth ( as used by Thomas 1963) t h i s would only be an approximation  but  and crude representation  of a c t u a l ammocoete growth. Hardisty (1961), Okkelberg  (1922),  and Hubbs (1924) presented growth curves f o r lampreys up to transformation that are s i m i l a r to those of B r i t i s h Columbian lampreys. Hubbs (1924) presented a lamprey growth curve that r i s e s to an apex at metamorphosis and then decreases at the onset of sexual maturity. B r i t i s h Columbia ammocoetes grow mainly during the spring and summer so the curves shown r e a l l y are composed of a.number of steps of growth as shown i n F i g . 6 3 . Ammocoetes grow r a p i d l y during the f i r s t year of l i f e , then decrease growth over the winter, but increase growth again i n the s p r i n g . Complications of biology j u s t before transformation prevent a more d e t a i l e d mathematical representation of the growth curves. 16. Transformation  or Metamorphosis of Ammocoetes  L. planeri A few transforming i n d i v i d u a l s were c o l l e c t e d during September and October i n the Salmon River and during August i n the Tsolum R i v e r . Ammocoetes l a r g e r than 90 mm., ammocoetes, and adults are compared i n the  transforming  length-frequency  diagrams i n F i g . 72. A reduction of ammocoete s i z e at t r a n s formation could conceivably take place i n the Salmon River population because the l a r g e s t ammocoetes are l a r g e r than the transforming ammocoetes and there i s l i t t l e d i f f e r e n c e i n the range i n s i z e between the three groups of Lampetra. In the  162 Tsolum River c o l l e c t i o n one transforming l a r v a was l a r g e r than any of the ammocoetes but i t .is d i f f i c u l t to draw any conclusions about reduction i n s i z e . f r o m t h i s observation. Most workers who have examined transforming larvae have reported that ammocoetes decreased i n length at the onset of metamorphosis  ( Meek 1916, Hubbs 1924, MacDonald 1959,  Zanandrea 1951, 1954, 1957, 1961, Hardisty 1961, Knowles 1941, and Leach 1940). Leach (1940) has found by growing ammocoetes that they reduce t h e i r length by 10 percent  at'metamorphosis.  He maintains that ammocoetes may spend an e n t i r e year i n the f u l l grown c o n d i t i o n or "rest period" before onset of the transformation p e r i o d . He found that o n e - t h i r d of the ammocoetes w i t h i n the l i m i t s of'transformation s i z e transform w i t h i n a year. Gage (1927) suspected a r e s t period e x i s t e d i n the sea lamprey. A r e s t period could conceivably e x i s t i n the Lampetra population i n B r i t i s h Columbia because there i s l i t t l e difference i n the s i z e range from the l a r g e s t ammocoete to the a d u l t s . Thus growth could stop, or the ammocoetes could | decrease i n l e n g t h , before  transformation.  Leach (1940) d i v i d e d the transformation period i n t o three s u b - d i v i s i o n s : a r e s t period which precedes metamorphosis and extends f o r one year, the l a t t e r part being a non-feeding stage; an e a r l y transformation period of two or three months which i n B r i t i s h Columbia Lampetra probably extends from August to November; an immature adult period ends transformation and extends from November to March or e a r l i e r f o r Lampetra. Leach reported that t h e . ' i n t e s t i n e  of the e a r l y ammocoete stage was  MOC  t> H Z 5  NUMBER  vi  LAMPREY  NUMBER  OF  LAMPREY  -1—  fa)  U  o I m rn -H z m o  OF  -  CO  -1  >  1 n  z  I  m  -i o  a X  m > p o c c m x— z -\ o  f Z  "  CO •< O D T1  3  >  X  >  X  V)  • z  Z  2  o  m  t—  a >  X CO  >  OF  TRA  m  H  0) VI  m z o  >  z  cn  m Tl z o  -» a o Z  (A TJ  z o  X m z rc >  CA 31 < >  m  H >  O c w  VO  25 > x  Ul  >  z o  O  CO  H  *> X Z >  Z  o o -n o o m x —» Z m z CO o  >  X <  >  m  X  o •n m z  -t o CO X X m z c  (A  o o  I >  55 \< W  X  164  empty and reduced i n s i z e from that of the l a r g e s t ammocoetes. This a l s o occurred i n the same stage f o r the Salmon River brook lamprey.  ' Changes i n shape and form that occur during the t r a n s -  formation from ammocoete to adult can be seen i n F i g . 73 74.  and  The transformation from ammocoete to t h e . e a r l y transforma-  t i o n stage ( F i g . 73-B)  apparently occurs r a p i d l y w i t h i n a  month or l e s s (leach 1940). The f i r s t signs of transformation are the enlargement and formation of the eye, while the l a t e r a l l i p s of the head take on a pointed shape. The mouth remains incompletely developed f o r many months and g r a d u a l l y f i l l s w i t h teeth and increases i n s i z e (Leach 1 9 4 0 ) . The  gill  openings become rounded and the b r a c h i a l basket enlarges.  The  v e n t r a l groove of the endostyle disappears in' the older forms ( F i g . 7S-A). The n a s o - p i t u i t a r y i s enlarged and s p e c i a l i z e d i n the transforming and adult forms (Kleerekoper and van E r k e l I960).  Leach (1940) described d e t a i l e d changes i n I .  fossor  by observing metamorphosis i n the l a b o r a t o r y . He observed that the i n t e s t i n e i n large ammocoetes was a few m i l l i m e t r e s i n diameter and f u l l of food, but i n transforming larvae the i n t e s t i n e was  empty and reduced i n diameter to l e s s than  one  m i l l i m e t r e . The i n t e s t i n e s of B r i t i s h Columbia transforming larvae, showed the same reduction i n s i z e and i t a l s o contained l i t t l e or no food. Transforming  larvae were obtained from B r i t i s h  Columbia streams by digging i n the sand, l e a f and mud  sediment  beds during t h e . l a t e summer or e a r l y f a l l . A l l specimens of  165  F i g . 74  F i g 75  A comparison of the s i z e and shape of transforming l a r v a of L. p l a n e r i . A- ammocoete. B- l a r g e transforming ammocoete (Tsolum River) C- small transforming l a r v a . D- female adult (Salmon R i v e r ) . E- male adult (Salmon R i v e r ) .  A comparison of the head of L . p l a n e r i . 1- L a t e r a l view. 2- V e n t r a l view. 3- Dorsal view. A- Ammocoete. B- Transforming a d u l t . C- Adult (length- 140 mm.).  166 transforming larvae were taken from deep water (> 3 f e e t ) . Transforming larvae were never c o l l e c t e d i n winter from the Salmon R i v e r . This suggests that the transforming  larvae  occupy a habitat that i s not sampled or can escape the c o l l e c t ing device. Leach (1940) observed transforming larvae i n the l a b o r a t o r y and found they appeared to be h i d i n g with the pharynx extended above the burrow and r e t r a c t e d i n t o the burrow when danger threatened. Ammocoetes w i l l reburrow under s i m i l a r circumstances.  Gage (1928) reported that  lamprey remain i n the mud  transforming  and sand l i k e the l a r v a e , but they  are often found i n deeper water. Entosphenus Transforming larvae were c o l l e c t e d i n the B i g Qualicum River i n August i n d i c a t i n g that transformation would s t a r t i n J u l y . No transforming larvae were obtained i n the f a l l i n other r i v e r s of B r i t i s h Columbia but larvae i n the l a t e transformation stage were obtained i n the N i c o l a and Thompson Rivers i n December and March. This i n d i c a t e s a r a p i d transformation or a f a l l transformation. Transforming Entosphenus larvae are smaller i n s i z e than Lampetra larvae . although the N i c o l a River larvae should, be l a r g e r as they were :  c o l l e c t e d i n March. C o l l e c t i o n s suggest that transformation' takes one year to complete as transformed  larvae or e a r l y adult  stages were c o l l e c t e d on the i r r i g a t i o n screens of the N i c o l a River i n August (C.C. Lindsey, personal communication). The presence of a r e s t period was not determined but the absence of l a r g e ammocoetes i n the N i  C 0  l a River could mean reduced  167 growth or absence of the r e s t period. The same changes i n shape occur i n transforming Entosphenus as those i n Lampetra. D. Community R e l a t i o n s h i p and M o r t a l i t y Lampetra Lampreys are the most abundant permanent f i s h - l i k e r e s i d e n t s i n the Salmon R i v e r . They u t i l i z e diatoms and  de-  caying organic matter of the stream as t h e i r major food. This food i s not u t i l i z e d by f i s h e s of the stream so no competition f o r a food source e x i s t s between f i s h e s and ammocoetes. However, i n the Salmon R i v e r , the microscopic algae and d e t r i t u s i s used by ammocoetes, f r e s h water clams (Anodonta),  c r a y f i s h ( P a c i f a s t a c u s ) , ephemeroptera nymphs  and oligochaetes (Tubifex). The ammocoetes appear to be h i g h l y adaptive and s u c c e s s f u l members of the bottom community of the stream.  The predation upon lamprey ammocoetes by f i s h ,  am-  phibians, b i r d s , and mammals i s doubtful because of the f o s s o r i a l nature of the ammocoete and the d i s t a s t e f u l substance i n i t s s k i n . The greatest m o r t a l i t y i n ammocoetes occurs j u s t a f t e r hatching when the yolk sac i s used up p r i o r to feeding. P i a v i s (I960) found the highest m o r t a l i t y r a t e i n the landlocked sea lamprey occurred from hatching to the pre-larvae stage. Lennon (1955) reported a l a r g e percentage of ammocoetes died soon a f t e r hatching. Lamprey eggs and very small emergent ammocoetes were eaten by salmonld f r y i n the l a b o r a t o r y . However, i n the stream the adhesive eggs are securely buried i n the nest and ammocoetes emerge at n i g h t , thus  escaping  168 predation, as i s i n d i c a t e d by a l a c k of ammocoete remains i n the f r y stomachs. P o t e n t i a l lamprey predators such as the blue heron (Ardea herodias) . racoon (Procyon l o t o r ) , and the mink (Mustela vison) are present i n the Salmon River area, but due to the abundance of salmon and t r o u t f r y throughout the year, i t i s u n l i k e l y that they would burrow i n t o the mud f o r ammocoetes. On numerous occasions observations were made of predation by Ephemeroptera nymphs and small c r a y f i s h upon ammocoetes burrowed i n the mud. The raven (Corvus corax) was observed eating spawning Lampetra on f i v e occasions and many marks s i m i l a r t o that made by a b i r d ' s b i l l have been seen i n Lampetra and Entosphenus i n the Salmon R i v e r . Hardisty (1961) found, " a r e l a t i v e uniform r a t e of m o r t a l i t y which the estimate's show i s hardly s u r p r i s i n g i n view of the s h e l t e r e d and s t a b l e h a b i t a t of the ammocoetes, where except during metamorphosis, there i s l i t t l e tendency f o r segregation of the animals w i t h respect t o t h e i r age". He assumes that there i s a very heavy m o r t a l i t y during the f i r s t few months of l a r v a l l i f e , e s p e c i a l l y i n the period when the newly emergent ammocoetes are d r i f t i n g downstream to the ammocoete beds and again during the vulnerable phase of metamorphosis. M o r t a l i t y a f t e r hatching was observed i n the Salmon Hiver lamprey, but m o r t a l i t y of emergent ammocoetes and t r a n s forming l a r v a e was not  observed.  Entosphenus The community r e l a t i o n s h i p s of ammocoetes of  169  Entosphenus are probably s i m i l a r to those of Lampetra. Adult Entosphenus are suspected  of having greater m o r t a l i t y due to  f i s h predators i n the sea. The population explosion i n the Great Lakes:.of Canada of the landlocked sea lamprey has been r a r e l y equalled i n h i s t o r y and can be a t t r i b u t e d i n part to the absence of predators or b i o t i c c o n t r o l i n the f r e s h water environment. The endemic f r e s h water forms, " o f f e r l i t t l e or no c o n t r o l by competition, disease, p a r a s i t i s m , or predation" (McLain 1951). The discovery of the p r o t e c t i v e substance i n the s k i n of lamprey which protects them from many species of predacious f r e s h water f i s h , may account f o r the low m o r t a l i t y r a t e . However,' there are few records of lampreys i n stomach a n a l y s i s of marine fishes.' Adult lampreys were recorded i n the stomach of a sperm whale o f f the Queen C h a r l o t t e Islands and from the mouth of a f u r s e a l o f f Cape F l a t t e r y ( P i i e 1953) which i n d i c a t e that lampreys go many miles i n t o the open sea and would be s u c e p t i b l e t o great predation. The e f f e c t of Entosphenus p a r a s i t i s m on the f i s h of the sea and c e r t a i n Vancouver Island lakes i s pronounced but the extent to which f i s h are k i l l e d or a f f e c t e d by the p a r a s i t e i s not known. The number of ammocoetes i n r i v e r s and adults i n lakes and the sea was s u b s t a n t i a l i n many areas of B r i t i s h Columbia. Their e f f e c t on other community members was d i f f i c u l t to determine. L i m i t e d observations from the Salmon River suggest that ammocoetes occupy a n i t c h and e x p l o i t a food supply that i s not u t i l i z e d by many other community members.  170 DISCUSSION Lampreys are very common i n the c o a s t a l streams i n B r i t i s h Columbia, but they have been studied very l i t t l e . Lamprey ammocoetes occupy the s o f t mud and sand beds i n quiet pools and along the bank where sediments accumulate when the current i s reduced.  Most stream surveys f a i l to i n c l u d e  lampreys as part of the aquatic fauna because of the  lampreys'  f o s s o r i a l nature and r e s t r i c t e d d i s t r i b u t i o n to c e r t a i n sections of stream bottom. The d i s t r i b u t i o n of lampreys w i t h i n the c o a s t a l streams i s incompletely known but extensive c o l l e c t i n g f i n d them occupying most streams.  may  A l l streams examined on  Vancouver I s l a n d revealed lamprey ammocoetes as r e s i d e n t s . The s i z e of E. t r i d e n t a t u s populations and t h e i r d i s t r i b u t i o n along the coast should r e v e a l the extent of predation. The systematics of B r i t i s h Columbian brook lamprey i s i n need of r e v i s i o n as the Salmon River population and others examined are s u f f i c i e n t l y d i f f e r e n t from the European form to warrant i t s being given a separate species name. There appear to be many races of. L. p l a n e r i i n B r i t i s h Columbia., that have d i f f e r e n t tooth p a t t e r n s , myotome counts, and growth rates-.  A key to separate large ammocoetes of L.  p l a n e r i from those of E. t r i d e n t a t u s i s presented, but a key to ammocoetes of smaller s i z e c l a s s e s i s needed.  Separation  of l a r v a l ammocoetes by the s i z e of gonads using the method used by Hardisty (i960) seems to o f f e r p o s s i b i l i t i e s .  The  171  p o s i t i o n of L. a y r e s i and i t s l i f e h i s t o r y i s unknown except f o r a few p a r a s i t i c adults that have been c o l l e c t e d on f i s h i n the S t r a i t of Georgia. The spawning behaviour o f lampreys o f f e r s a r i c h and unexplored f i e l d f o r the comparative e t h o l o g i s t . The p r i m i t i v e phylogenetic p o s i t i o n o f f e r s i n t e r e s t i n g s t a r t i n g points to t r a c e o r i g i n s and evolutionary development of spawning behaviour found i n f i s h .  Adult lampreys  w i l l spawn r e a d i l y i n s t i l l or running water i n an aquarium c o n t a i n i n g g r a v e l , yet feeding and c o n d i t i o n i n g requirements present i n f i s h are apparently almost non-existent. The change i n spawning behaviour with temperature changes presents an i n t e r e s t i n g behaviour pattern. The e f f e c t o f temperature on spawning behaviour of L. p l a n e r i may be present i n other species of lampreys and might help to explain aspects of t h e i r biology.  The sex-  r a t i o of spawning adults from the Salmon River was found t o be predominantly female at the s t a r t of the season, but l a t e r i n the season males predominated Surface, 1897).  ( a l s o recorded by  A review of the data presented by Applegate  (1950) on the s e x - r a t i o i n Carp Creek reveals that there may be some c o r r e l a t i o n between s e x - r a t i o and temperature as w e l l as between s e x - r a t i o and abundance and year c l a s s s i z e . In h i s observations the lowest s e x - r a t i o i n 1947 and 1948 imply that the temperature was never above 60°F. u n t i l l a t e May.  In 1949 the temperature was above 60°F, twice i n e a r l y  A p r i l and May and the s e x - r a t i o was the highest i n t h i s year.  172  In 1947 h i s data showed a 5:1 r a t i o throughout the season with a 2:1 r a t i o i n e a r l y May and a 3 ; 1 r a t i o i n June. the Salmon River observations  From  the low temperatures may be  responsible f o r causing the males t o bury i n the g r a v e l or becoming l e s s a c t i v e ; hence they w i l l not be c o l l e c t e d as r e a d i l y as the females. C o l l e c t i o n s of adult lampreys f o r s e x - r a t i o a n a l y s i s should be made at r e g u l a r i n t e r v a l s throughout the season t o overcome the sampling e r r o r associated with behaviour d i f f e r e n c e s caused by temperature.  C o r r e c t i o n f o r a longer l i f e of males  during the spawning season should also be considered r a t i o determinations.  i n sex-  The L. p l a n e r i males of the Salmon  River were found t o l i v e considerably longer than the females at a l l temperatures t e s t e d .  Zanandrea  (1^61) found that the  s e x r r a t i o of I t a l i a n lampreys increased throughout the spawn= ing  season and he suggested that t h i s might be due t o the  greater s u r v i v a l r a t e of the male.  However, from the Salmon  River data, low stream temperature as w e l l as longer l i f e of males could be suspected.  Hardisty (1954) suggested that the  d i f f e r e n c e i n s e x - r a t i o i n lampreys may be due to, environmental conditions such as temperature and n u t r i t i g n . The comparative embryolqgy of B r i t i s h Qglumb,ian lampreys could r e v e a l basic s i m i l a r i t i e s that could be used to t r a c e the e v o l u t i o n of d i f f e r e n t species o f lampreys. The, early- ammocoete l i f e may r e v e a l taxonomic c h a r a c t e r i s t i c s t h a ^ could be used t o separate d i f f e r e n t species.  The range of-  temperature tolerance and the e f f e c t o f temperature on  173  development should prove h e l p f u l i n understanding  the b i o l o g i c a l  requirements and tolerance ranges that the animals can w i t h stand ( s i m i l a r to P i a v i s 1955). i s very important  The m o r t a l i t y during  hatching  because the stage when the yolk-sac i s  exhausted but before the j u v e n i l e becomes dependent on i t s own a b i l i t y to feed i s considered to be.the c r i t i c a l stage i n e a r l y l i f e of. most f i s h e s ( Beverton and Holt 1956). Sampling methods and s i z e are extremely  important  i n presenting an unbiased d e s c r i p t i o n of the population. I f only one sampling method i s used i t w i l l be very u n l i k e l y to- be representative of a l l age classes (Ricker 1958).  A great  v a r i e t y of c o l l e c t i n g methods that sample a l l stream h a b i t a t s would most l i k e l y be representative of the population.  Most  workers have used e i t h e r e l e c t r i c shockers or scooped the sediments onto the shore.  The f i r s t method s e l e c t s f o r the  l a r g e r specimens while the second does not produce adequate samples of the l a r g e r ammocoetes.  Both of these methods  plus downstream traps would produce the best sampling. D i f f e r e n t sections of the r i v e r , or even sections of the same pool, produce d i f f e r e n t s i z e c l a s s e s , thus the e n t i r e length of l a r g e sections of the r i v e r and .  each of the  bottom types should be sampled to account f o r d r i f t i n g or migrating f r a c t i o n s of the population. The. b i o l o g y of ammocoetes i s very d i f f i c u l t t o i n t e r p r e t and study i n the stream environment.  It i s d i f f i c u l t  to determine movement of ammocoetes'in the stream since small ammocoetes are impossible to mark by e x i s t i n g methods.  However.  174  organic dyes have r e c e n t l y proven s u c c e s s f u l i n marking lampreys (Wigley 1952).  The p r o t e c t i v e nature of the mech-  anism by which emergent ammocoetes leave the g r a v e l at night and s e t t l e downstream i n the pool areas i s poorly  understood.  Harden-Jones (1955) i n d i c a t e d from l a b o r a t o r y experiments that ammocoetes are photokinetic but h i s data a l s o i n d i c a t e d that ammocoetes are s l i g h t l y thigmotaxic.  This could e x p l a i n the  p o s s i b l e need by ammocoetes to have mud body surface.  i n contact with the  A thigmotaxic response i n conjunction with  d i u r n a l or c i r c a d i a n rhythms could account f o r downstream mig r a t i o n and d i s t r i b u t i o n i n the stream.  D i f f e r e n t year classes  are c o l l e c t e d in. d i f f e r e n t h a b i t a t s or bottom types, but  why  each s i z e group prefers a p a r t i c u l a r bottom type or current v e l o c i t y i s not known. D e t a i l e d a n a l y s i s of the f i l t e r feeding mechanism of ammocoetes requires f u r t h e r study.  The endostyle net can  apparently pick out diatoms and desmids from mud,  yet proto-  zoans and organic matter such as s t a r c h are r e j e c t e d .  The  r a t e of food passage through the gut and the a c t u a l u t i l i z a t i o n of the m a t e r i a l i s worthy of c o n s i d e r a t i o n . Ammocoetes seem to be able to withstand long periods without food as i s i n d i c a t e d by a reduction i n growth and food intake during the winter months.  This must cause change and  s h i f t s i n the metabolic requirements  of the animal.  The r e -  duction of the gut at transformation i n d i c a t e s a period of l i t t l e or no feeding i n the l a t e ammocoete stage.  The r e s t  period described by Leach (1940) may a l s o be associated with  175 a cessation of feeding.  The adults of both species studied do  not feed from the e a r l y f a l l u n t i l spawning, but the f a t accumulated by the ammocoetes of L . p l a n e r i , and from a p a r a s i t i c e a r l y adult l i f e of E. t r i d e n t a t u s i s used to keep the animal alive. The length of ammocoete l i f e has occupied the core of most lamprey work i n the past.  However, the nature of the  animal's biology and the d i f f i c u l t y i n separating the year classes may  have presented  d i s t o r t e d and inaccurate  inform-  a t i o n i n view of recent information as to the presence of a r e s t period.  Shortening i n length at transformation,  the  presence of a r e s t period, d i f f e r e n t i a l growth rates between the sexes, and d i f f e r e n c e s i n i n d i v i d u a l growth that o r i g i n a t e from a long spawning period make the a n a l y s i s of Salmon River data very d i f f i c u l t .  However, growth experiments could elim-  inate t h i s shortcoming and check length-frequency  data.  Leach  (1940) has shown that by growing ammocoetes the l e n g t h - f r e quency a n a l y s i s produces (usually) an age considerably than the a c t u a l age of the animal.  smaller  S t r a u f f e r (1962 ) prevented  recruitment i n the sea lamprey and allowed the population to go t o e x t i n c t i o n to show that l a r v a l l i f e i s longer than previously calculated.  Wigley (1959) found a b e t t e r estimation  of age up to transformation can be obtained from weightfrequency d i s t r i b u t i o n s . The determination  of age s t r u c t u r e and growth i n  lamprey populations by the p r o b a b i l i t y paper method (1954) f o r a n a l y s i s of length-frequency  (Harding  distributions offers  176 greater e f f i c i e n c y than the biased v i s u a l examination of modes. However, c e r t a i n assumptions and l i m i t a t i o n s must be considered before the method can be undertaken.  Each dominant year c l a s s  may be represented by a mode i n a simple case but there i s always a p o s s i b i l i t y that the sample of ammocoetes may possess one or more scarce broods between the modes.  The major mode  may a l s o be composed of two or more overlapping d i s t r i b u t i o n s and must be considered as w e l l as the type of d i s t r i b u t i o n present i n the population.  Normal d i s t r i b u t i o n s w i t h i n each  mode are u s u a l l y assumed, but d i s t r i b u t i o n s should be s t a t i s t i c a l l y examined.  The three assumptions suggested by Ricker  (1958) seem t o apply t o the lamprey population analysed when a von B e r t a l a n f f y growth curve i s assumed.  These are:  1. That there i s no d i f f e r e n c e between yearclasses i n respect t o rate of growth at any given age. 2. That the f i s h taken constitute a random sample of each of the age-classes i n volved (not n e c e s s a r i l y a random sample of s e v e r a l age-classes simultaneously). 3. That there be no c o r r e l a t i o n between s i z e of a f i s h w i t h i n an age-class> and the m o r t a l i t y r a t e t o which i t i s subject. I t i s worth noting that an a n a l y s i s which gives.a s a t i s f a c t o r y f i t may not n e c e s s a r i l y be the most complete p i c t u r e of the f a c t s which may r e a l l y conform t o one of the many complex s o l u t i o n s .  There may be smaller groups w i t h i n  the samples and each normal curve may i n essence be bimodal i f both sexes are represented. However,neither the graphic method nor any other w i l l give a complete and undisputed solution.  The simplest s o l u t i o n i s l i k e l y to be the most  177 s i g n i f i c a n t , b i o l o g i c a l l y as w e l l as s t a t i s t i c a l l y ( H a r d i n g 1949). T r a n s f o r m a t i o n o f lamprey ammocoetes i s p o o r l y u n d e r s t o o d , but t h e mechanism t h a t i n i t i a t e s t h e change has been t h e s u b j e c t o f s p e c u l a t i o n by many w o r k e r s .  Trans-  f o r m a t i o n was thought t o be a s s o c i a t e d w i t h t h e f o r m a t i o n o f the t h y r o i d g l a n d o r unique s e m i - f o l l i c l e s w i t h i n t h e endos t y l a r organs (Leach 1939)•  The s e m i - f o l l i c l e s a r e thought  t o r e p r e s e n t t h e t r a n s f o r m a t i o n t i s s u e and a c c o u n t s f o r s p e c i a l i z e d d i f f e r e n t i a t i o n o f t h e a n i m a l r a t h e r t h a n growth in length.  Remy (1922) and Leach (1944, 1946) i n j e c t e d  t h y r o i d and i o d i n e compounds i n t o ammocoetes but t h i s t o produce metamorphosis. metamorphosis  Horton (1934) i n i t i a t e d  anuran  by i n j e c t i n g t h y r o i d from t h e a d u l t lamprey.  The e n d o s t y l e o f t h e ammocoete c o n t a i n e d no i o d i n e 1941)•  failed  (Knowles  Knowles f e d t a d p o l e s ammocoete e n d o s t y l e s but no  metamorphosis  occurred.  He a l s o t r i e d t o a c c e l e r a t e meta-  morphosis by i n j e c t i n g a n t e r i o r - p i t u i t a r y e x t r a c t , but t h i s was  unsuccessful.  P i c k f o r d and A t z (1957) a n t i c i p a t e t h a t  hypophysisectomy would prevent t h e metamorphosis  o f ammocoetes.  In t a d p o l e s a s h o r t p e r i o d o f s t a r v a t i o n j u s t b e f o r e metamorphosis  i s said t o accelerate the transformation into  t h e a d u l t form ( B a r f u t h 1887, quoted by Thompson 1942). H a r d i s t y (1961) s u g g e s t s t h a t a d e c l i n e i n abundance o f phytop l a n k t o n i n l a t e summer might be r e s p o n s i b l e f o r t h e s e a s o n a l onset of metamorphosis  i n lampreys.  However, t h e lampreys o f  Leach (1940) and t h e lampreys s t u d i e d here showed a reduced  178  i n t e s t i n e and an absence of food at the s t a r t of metamorphosis i n l a t e summer.  Larger ammocoetes than the transforming  larvae  were a c t i v e l y feeding and t h e i r i n t e s t i n e s were f u l l of phytoplankton.  This suggests,that  transformation i s associated w i t h  a cessation of.feeding by the ammocoetes. P a r a s i t i s m i n the lake environment and I n the sea i s poorly understood f o r B r i t i s h Columbia lampreys. has been recorded  Parasitism  i n E l s i e Lake and the sea from c o l l e c t i o n s  of small a d u l t s or observations of scars.  Larger lampreys  have been recorded attached to large cutthroat t r o u t i n Cowichan Lake. The occurrence of landlocked races of lampreys i n E l s i e and Cowichan Lakes i s suspected b u t . l i t t l e study  had  been d i r e c t e d to t h i s area u n t i l the l a s t few years and mation, i s s t i l l i n c o n c l u s i v e .  infor-  The extremely small s i z e of  scars on the E l s i e Lake t r o u t i s i n d i c a t i v e of a reduction i n s i z e t h a t i s associated with landlocked  races.  The e f f e c t of p a r a s i t i c lampreys on marine f i s h  has  produced few records of incidence except f o r t r o l l - c a u g h t salmon (Milne I960, personal communication). reasonable  I t would seem  to assume that i f lampreys can seek out and attach  to open water f i s h l i k e the salmon, that they would have l i t t l e d i f f i c u l t y a t t a c h i n g to slower moving, bottom d w e l l i n g fish.  I f lampreys are preying on other f i s h besides salmon,  the incidence may  not be recorded or may  be l e s s common.  evidence of lamprey k i l l i n g f i s h has been presented Columbia.  No  in British  179 The homing i n s t i n c t of lampreys o f f e r s a unique f i e l d f o r study, e s p e c i a l l y since Wigley (1952) has found that organic dyes can be used t o mark lamprey s u c c e s s f u l l y . The long migrations of E. t r i d e n t a t u s up the Fraser River and Skeena River c e r t a i n l y suggest a homing tendency. Lamprey predation i n Cowichan and E l s i e Lakes and i n the sea may be a threat t o the f i s h population.  However,  the problem must be given serious study before a r e a l i s t i c a p p r a i s a l can be made.  Lake populations must be c a r e f u l l y  watched i f they become landlocked.  The use of the lampricide  TFM ( 3 - t r i f l u d r - m e t h y l - 4 nitrophenol) has been very  success-  f u l , and popular i n k i l l i n g ammocoetes i n Eastern North American streams.  The chemical k i l l s ammocoetes i n the mud  but does not a f f e c t other f i s h ( Applegate et a l . 1957). This chemical could be used to reduce the number of E. t r i d e n t a t u s ammocoetes i n the streams and lakes where popul a t i o n s and p a r a s i t i s m warrant i t .  Lake lampreys (Kennedy 1958)  have complicated the c o n t r o l problem i n the Great Lakes by spawning i n the lakes and thus making c o n t r o l impossible. The e v o l u t i o n or s p e c i a t i o n of n o n - p a r a s i t i c lampreys from p a r a s i t i c lampreys has received much speculation i n the past, Hubbs (1924), Zanandrea (1959, 1961), and Hardisty (1963). A n o n - p a r a s i t i c l i f e i s associated with a supposed shortening of the. l i f e c y c l e , removal of the migratory phase, shortening of the length of the body, and a reduction i n d e n t i t i o n and fecundity.  "The degenerate or brook lampreys appear t o have  been independently  derived from d i f f e r e n t p a r a s i t i c s p e c i e s " ,  •" according t o Hubbs (1924)-  180' Zanandrea (I96l) discussed,  speciation. of lampreys and arranged them i n p a i r s where nonp a r a s i t i c forms have evolved from p a r a s i t i c forms (present in' the genus Ichthyomyzon, Lampetra, and Eudontomyzon). One  p o s s i b l e paired group of lampreys i n B r i t i s h  Columbia i s ' t h a t of L. p l a n e r i ( n o n - p a r a s i t i c ) and L. a y r e s i ( p a r a s i t i c , e a r l i e r c a l l e d L. f l u v i a t i l i s ) .  The  great  s i m i l a r i t y between the p a i r i n d i c a t e s the recent evolutionary divergence  of the two species (Hardisty 1963).  However, t h i s  p a i r could be. North American extensions of European L. p l a n e r i and L. f l u v i a t i l i s that have been separated  geographically  and have had time to d i f f e r e n t i a t e considerably from the form.  parent  No paired form of E. t r i d e n t a t u s occurs at present  a small race that i s shorter i n length may be e v o l v i n g .  but This  form may be estuarine i n i t s p a r a s i t i c l i f e and may be s i m i l a r to a landlocked smaller form that i s suspected  in Elsie  and  Cowichan Lakes. Paired lampreys are u s u a l l y morphologically very s i m i l a r and develop along p a r a l l e l l i n e s but t h e i r b i o l o g y i s very d i f f e r e n t (Zanandrea 1 9 6 l ) .  One of the paired species  does not feed a f t e r metamorphosis while the other form preys on f i s h .  (parasitic)  In the non p a r a s i t i c form the gonads begin  to develop during metamorphosis ( a small egg number), but i n the p a r a s i t i c forms, gonads do not develop u n t i l the end of the feeding stage ( l a r g e egg number). The formation of a landlocked race from a p a r a s i t i c lamprey seems to i n d i c a t e the f i r s t step i n divergence  to a  • ; n o n - p a r a s i t i c existence.  181  Landlocked sea lampreys are charac-  t e r i z e d by a,reduction i n s i z e and f e c u n d i t y , but a reduced m o r t a l i t y u s u a l l y causes an explosive increase i n numbers. Landlocked sockeye salmon or kokanee Qncorhynohus nerka i n B r i t i s h Columbia lakes have shown s i m i l a r types of changes to those of landlocked lampreys.  Kokanee have reduced s i z e and  egg number but have increased i n numbers when t h e i r anadromous migration was forsaken. The landlocked forms of p a r a s i t i c lampreys have caused great reductions i n the commercial f i s h e r y (P.  marinus) i n the Great Lakes Of North America (Wigley 1959),  and the l i t t l e known landlocked form of L. f l u v i a t i l i s of Lake Onega and Lake Ladoga i n Russia (Berg 1931)•  I t w i l l be i n t e r -  e s t i n g i n these instances to observe the d i r e c t i o n of e v o l u t i o n of the landlocked lampreys a f t e r the f i s h population i s removed or reduced.  Laboratory r e a r i n g of the landlocked form and  removal of the feeding stage or s u b j e c t i n g them to s a l i n i t y changes could^have i n t e r e s t i n g  i m p l i c a t i o n s to lamprey l i f e  cycles. The i n t e r a c t i o n s between lampreys and other community members have never been i n v e s t i g a t e d .  Ammocoetes seem to  occupy a h a b i t a t and e x p l o i t a food supply (algae) that i s unused i n most stream environments. the  The p r o t e c t i v e nature of  s k i n , reduced predation, f o s s o r i a l h a b i t s , and nocturnal  behaviour enable ammocoetes to have a low m o r t a l i t y r a t e . Speculation as to why lampreys dominate the f r e s h water e n v i r onment while t h e i r numbers are kept at a low l e v e l by a period i n the sea suggests some i n t e r e s t i n g e c o l o g i c a l r e l a t i o n s . The  182  difference  i n feeding habits of predatory f i s h i n both habitats  (more swallowers i n the sea) or j u s t increased numbers of predators may cause the d i f f e r e n c e .  The behaviour of lamprey  prey i n the lakes may be quite d i f f e r e n t from that of d i f f e r e n t species i n the sea. The landlocked form has a d e f i n i t e s u r v i v a l advantage despite the increased egg number of the sea lamprey. Lampreys o f f e r a f a s c i n a t i n g and r e a d i l y a v a i l a b l e source of i n t e r e s t that' warrants f u r t h e r extensive and s p e c i f i c b i o l o g i c a l study beyond the scope of the present work i n B r i t i s h Columbia.  introductory  183  SUMMARY OF SPAWNING BEHAVIOUR A. Spawning Requirements 1.  P h y s i o l o g i c a l l y mature sex products.  2.  Gravel bottom i s e s s e n t i a l .  3.  Temperature above 10°C necessary to i n i t i a t e spawning.  4.  Current of one foot per second preferred but not  :  essential. 5.  Shade p r e f e r r e d but not e s s e n t i a l .  B. Prespawning 1.  Gather near the r i f f l e  2.  A c t i v e movement and searching on the r i f f l e  areas. area  (nocturnal) . 3.  Play w i t h stones and i n d i v i d u a l mock spawning a c t i o n s .  C. Nest Construction 1.  Rock l i f t i n g , temperature governs the sex that i n i t i a t e s the a c t i o n .  2.  Combined rock l i f t i n g and d i g g i n g .  3.  Digging a c t i o n .  D. Spawning Sequence 1.  Seeking out partner and c o u r t i n g u n t i l partner moves to nest.  2.  Courting and head grasping by the male.  3.  Undulating female drapes body i n the nest.  4.  Sex a c t , head grasping and entwining of the t a i l about the female, v i b r a t i o n s and release of sex products i n t o the g r a v e l .  5.  Eggs are covered and attached to sand grains i n the  184 bottom of the nest. 6.  Short r e s t period, one or both leave the nest f o r a period.  7.  Return to nest and repeat the procedure.  £.  Temperature modifies the behaviour of sexes during spawning .  9.  Communal spawning and c o i l i n g are associated w i t h high i n t e n s i t y spawning.  E. Post Spawning 1.  A l l animals die s h o r t l y a f t e r spawning - temperature c o n t r o l s the period of l i f e .  SUMMARY OF THE LIFE CYCLES A. Lampetra p l a n e r i ( as o u t l i n e d by Leach,  1940)  1.  Eggs are deposited i n streams from A p r i l to 'June.  2.  Embryonic period - two to four weeks and  dependent  on the temperature. 3.  Ammocoete growth, period of f i v e or more years buried i n the mud,, f i l t e r feeding.  4.  Ammocoete r e s t period of one year with reduced growth and reduction i n s i z e before transformation (speculation o n l y ) .  5.  E a r l y transformation period from August to November. Feeding stops and great changes i n body form occur.  6.  Immature adult period from November to March. Transformation i s completed and the sex organs enlarge.  185 7.  Active adult period and spawning- from A p r i l t o J u l y .  8.  Post-spawning adult period- a few days to a. month. Duration of ammocoete cycle more than f i v e years. Duration of l i f e cycle from egg to adult more than six  years.  1  Entosphenus t r i d e n t a t u s l.-5« 6.  s i m i l a r to Lampetra  Late transformation and migration to sea- November to August. Stops feeding i n the stream, but begins p a r a s i t i c l i f e when i t enters lakes or the sea.  7.  A c t i v e p a r a s i t i s m on f i s h i n the sea- twelve to twenty months.  8.  M i g r a t i o n upstream - J u l y t o September.  9.  Immature adult stage- October t o March. No feeding, h i d i n g under stones i n the stream.  10.  A c t i v e adult or spawning period - A p r i l t o J u l y .  11.  Post-spawning period- one or two days. Duration of ammocoete cycle i s more than f i v e years. Duration of l i f e c y c l e (egg t o adult) i s more than seven years.  186 CONCLUSIONS 1.  Eggs of L, p l a n e r i s t a r t e d hatching i n 15 days at 15°C. o and i n 13 days at 17 C.. E. t r i d a n t a t u s eggs s t a r t e d hatching four days l a t e r than L. p l a n e r i at the same temperature (15°C.).  2.  Two to three week o l d larvae emerge from the g r a v e l at n i g h t , are c a r r i e d downstream by the current to the s o f t mud bottom where they bury themselves when the current i s reduced.  3.  Small ammocoetes cannot maintain themselves on any bottom when the current i s greater than one foot per second.  4.  Emergent ammocoetes are unable to penetrate sand bottoms while l a r g e r ammocoetes can penetrate most bottoms but they prefer a sand, l e a f and s i l t bottom.  5.  The greatest concentration of ammocoetes were found i n the  sand, l e a f and s i l t beds of the pool areas at times  of reduced flow. 6.  Small ammocoetes change t h e i r burrows or move about i n the  7.  mud during each day.  Large ammocoetes of L. p l a n e r i can be separated from those of  E. t r i d e n t a t u s by myotome counts and examination of  pigment areas. 8.  B r i t i s h Columbia L. p l a n e r i i s quite d i f f e r e n t taxono m i c a l l y from the European form of the same species.  9.  The Salmon River adult L. p l a n e r i represents a dwarf race of the brook lamprey.  10.  Two  d i s t i n c t s i z e groups of E. t r i d e n t a t u s are  i n the, Salmon R i v e r . 11.  present  <  Incidence of E. t r i d e n t a t u s p a r a s i t i s m occurs i n E l s i e and Cowichan Lakes on Vancouver Island and i n the ^sea.  12.  Greatest incidence of p a r a s i t i s m by E. t r i d e n t a t u s i s confined to the e a r l y s p r i n g i n the lakes and to the summer i n the sea.  13.  •  More female L. p l a n e r i were c o l l e c t e d i n the lower Salmon River than i n the upper r i v e r .  14.  Female L. p l a n e r i are s i g n i f i c a n t l y l a r g e r than males i n the Salmon R i v e r .  15.  j  The egg diameter of both species i s s i m i l a r . The range of egg number f o r L. p l a n e r i i s 1,100  - 3,700 and that  of E. t r i d e n t a t u s i s 10,000 - 106,100. i  16.  Adult L. p l a n e r i spawn at temperatures above 10  o  C i n  the stream but at lower temperatures the females remain a c t i v e yet the males bury i n t o the g r a v e l . 17.  The spawning behaviour i s very s i m i l a r between the species examined and that recorded  18.  two  f o r other species.  A long spawning period from A p r i l to J u l y occurs f o r L. p l a n e r i i n the Salmon R i v e r , low temperature increases the period.  19.  ^  Spawning adult L. p l a n e r i prefer  r i f f l e areas i n the  stream that are shaded and contain a current greater than 1 f o o t per second. 20.  No'intromission species.  occurs during the spawning act i n both  21.  Temperature has a marked e f f e c t on the i n i t i a t i o n of nest c o n s t r u c t i o n and spawning behaviour between the sexes of L. p l a n e r i .  22.  Communal spawning and c o i l i n g are stages of high i n t e n s i t y spawning when one or more females deposit most of t h e i r eggs i n one nest.  23.  No p a i r bond e x i s t s between partners of L. p l a n e r i during spawning.  24.  Males l i v e longer than females during the spawning period.  25.  The length of the spawning period i s dependent on temperature f o r L. p l a n e r i .  26.  I n t e s t i n e s of ammocoetes of L. p l a n e r i contained dominantly  pre-  diatoms during the spring and summer, but  d e t r i t u s was most prevalent during the winter months. 27.  Lamprey adults and ammocoetes are not eaten by the salmonid and other f i s h of the Salmon R i v e r .  28.  The s k i n of lampreys contains a p r o t e c t i v e substance that i s d i s t a s t e f u l to c e r t a i n f i s h .  29.  Length-frequency a n a l y s i s should be c a r r i e d out only on l a r g e samples taken from many d i f f e r e n t h a b i t a t s and w i t h many d i f f e r e n t c o l l e c t i n g methods.  30.  Ammocoetes of L. p l a n e r i showed l i t t l e growth during the winter of the f i r s t two years of l i f e .  31. . Ammocoetes should be marked and grown i n a stream e n v i r onment to t e s t length-frequency a r e s t period.  data and the presence of  189 32.  The growth curve of the ammocoetes of L. p l a n e r i and E. t r i d e n t a t u s  i s very s i m i l a r f o r the populations  examined. 33.  P r o b a b i l i t y paper provides a most e f f i c i e n t and unbiased graphic s t a t i s t i c a l method f o r a n a l y s i s of polymodal length-frequency d i s t r i b u t i o n and age determination f o r lamprey populations.  190 LITERATURE CITED A p p l e g a t e , V.C., 1950a. N a t u r a l h i s t o r y o f t h e s e a lamprey, Petromyzon marinus, i n M i c h i g a n . U.S. Dept. I n t . , F.W.S., Spec. S c i . Rept., F i s h # 55: 237. 1950b. Sea lamprey spawning runs i n t h e Great L a k e s . Spec. S c i . Rept. U.S. F i s h W i l d l . S e r v . No. 61: 1-49. Baerends, G.P., 1957. The e t h o l o g i c a l a n a l y s i s o f f i s h b e h a v i o u r . The P h y s i o l o g y o f F i s h e s , E d i t e d by M.E. Brown, Academic P r e s s , New York, London, V o l : I I . B e r g , L.S., 1931. A r e v i e w o f t h e lampreys o f t h e n o r t h e r n hemisphere. Annuaire Du-Mussee Z o o l o g i q u e De. L Academic Des S c i e n c e De L ' u r s s , V o l . 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Zool., Univ. Mich., (3): 12. Remy, P., 1942. L'iode et l a metamorphose de 1'ammocoete b r a n c h i a l i s et Petromyzon p l a n e r i (Bloch). CR. Soc. B i o l . P a r i s , 86: 129-131Rensch, B., 1959. Evolution above the species l e v e l . Methuen, London. Ricker, W.E., 1958. Handbook of computations f o r b i o l o g i c a l s t a t i s t i c s of f i s h populations. F i s h e r i e s Research Board of Canada. B u l l e t i n No. 119. Sawyer, 1959- Burrowing a c t i v i t i e s of the l a r v a l larmpreys. Copeia f o r 1959, (3): 256-257S c h r o l l , F., 1959- Zur enahrungsbiologie der s t e i r i s c h e n ammocoten Lampetra p l a n e r i (BlochT und Eudontomyzon danfordi (Regen). I n t . Rev. Ges. H y d r o l i n l . , 44 (3) '• 395-421. S c h u l t z , L.P., 1930. The l i f e h i s t o r y of L. p l a n e r i (Bloch) with a s t a t i s t i c a l a n a l y s i s of the rate of growth of the larvae from western Washington. Occ. pap. Mus. Zool., Univ. Mich., (221): 1-35S c o t t , D.P., 1956-57. Spawning requirements of sea lamprey. Appendix 0. Annual Report of the B i o l o g i c a l S t a t i o n and the Technological U n i t , London, Ontario, 1956-57. S t a u f f e r , T.M., 1962. Duration of l a r v a l l i f e of sea lampreys i n Carp Lake R i v e r , Michigan. Trans. Amer. F i s h . Soc. Vol. 91 (4): 422-423. Surface, H.A., 1897. The lamprey of c e n t r a l New York. B u l l . U.S. F i s h . Comm. 17: 209-215.  195 Thomas, J . ^ . , 1 9 6 2 . The f o o d and growth o f brown t r o u t (Salmo t r u t t a ) and i t s f e e d i n g r e l a t i o n s h i p s w i t h t h e salmon p a r r (Salmo s a l a r L.) and t h e e e l ( A n g u i l l a a n g u i l l a L.) i n t h e R i v e r T e r f y , West Wales. J o u r n a l Animal E c o l o g y : 3 1 * Thomas, M.L.H., 1 9 6 3 • S t u d i e s on the b i o l o g y o f ammocoetes i n streams. M a n u s c r i p t Report S e r i e s No. 742, F i s h e r i e s Research Board of Canada. Thompson, D'Arcy W.,  1942. Growth and form.  Cambridge.  V l a d y k o v , V.D., 1951. F e c u n d i t y o f Quebec l a m p r e y s . The Canadian F i s h C u l t u r i s t , The Dept. of F i s h e r i e s of Canada. , 1955. Lampetra z a n a n d r e a i , a new s p e c i e s o f lamprey f r o m N o r t h e r n I t a l y . C o p e i a , 1955. 3: 215-223. V l a d y k o v , V.D., and W.I._ F o l l e t t , 1958. R e d e s c r i p t i o n o f Lampetra a y r e s i i (Gunther) o f Western N o r t h A m e r i c a , a s p e c i e s of lamprey ( P e t r o m y z o n t i d a e ) d i s t i n c t from Lampetra f l u v i a t i l i s - ( L i n n a e u s ) of Europe. 15 ( l ) : 47-77. W i c k e t t , P. P a c i f i c B i o l o g i c a l S t a t i o n , Nanaimo. P e r s o n a l communication and use o f u n p u b l i s h e d d a t a . W i g l e y , R.L., 1952. A method of marking l a r v a l l a m p r e y s . C o p e i a , 1952. No. 3 : 2 0 3 - 2 0 4 . ,1959. L i f e h i s t o r y o f the sea lamprey of Cayuga Lake, New York. U.S. Dept. I n t . F i s h and W i l d l i f e S e r v . F i s h B u l l . 59 (154): 561-617. Young, J.Z., 1935. The p h o t o r e c e p t o r s o f l a m p r e y s . I . L i g h t s e n s i t i v e f i b r e s i n the l a t e r a l l i n e n e r v e s . JOurn. Exp. B i o l . 12 ( 3 ) : 229-238. Young, J.Z. and CW. B e l l e r b y , 1935- The response o f t h e lamprey t o i n j e c t i o n s Of a n t e r i o r l o b e p i t u i t a r y e x t r a c t . J . Exp. B i o l . 12: 246-253. Zanandrea, G., 1951. R i l i e v i e c o n f r o n t ! b o m e t r i c i e b i o l o g i c i s u l , Petromyzon (Lampetra) p l a n e r i ( B l o c h ) . N e l l e acque d e l l a marca t r e c i g i a n a . B o l l e t i n o d i P e s c a , P i s c i c o l t u r a e I d r o b i o l o g i a Anno. X X V I I , 6: 53-78. .  i , 1954. Note s u l l a e c o l o g i a e d i s t r i b u z i o n e i n I t a l i a d e l l a lampreda d i r u s c e l l a (Lampetra p l a n e r i ) , ( B l o c h ) . B o l l . Pesca P i s c i c . I d r o b i o l . 8: 1 - 2 0 , , 1961. S t u d i e s oh European l a m p r e y s . E v o l u t i o n , 15 ( 4 ) : 523-534.  

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