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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 Pletcher B.Sc, University of B r i t i s h Columbia, 195$. A Thesis Submitted In P a r t i a l Fulfilment Of The Requirements For The Degree Of Master of Science i n the Department of Zoology We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA October, 1963 I n p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of the requirements f o r an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r reference and study. I f u r t h e r agree that per-m i s s i o n f o r extensive copying of t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the Head of my Department or by h i s r e p r e s e n t a t i v e s . I t i s understood that copying i or p u b l i -c a t i o n of t h i s t h e s i s f o r f i n a n c i a l gain s h a l l not be allowed without my w r i t t e n p e r m i s s i o n . Department of The U n i v e r s i t y of B r i t i s h Columbia,. Vancouver 8, Canada. Date S" e^ fc-eto^  L^rf /?<^3 ABSTRACT The analysis of the l i f e history was carried out from co l l e c t i o n s that were predominantly Lampetra planeri from the Salmon River and Entosphenus tridentatus from the Nicola 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 for separating large ammocoetes. The duration of adult l i f e , d i s t r i b u t i o n within streams, length, 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 laboratory observations. Temperature affected length of spawning period, spawning behaviour, sex r a t i o , and r e l a t i v e abundance of L. planeri. 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 carried 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 reflected 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 with sand, l e a f , and s i l t bottoms. Ammocoetes kept i n aquaria moved t h e i r burrows frequently. Ammocoete intestines contained predominantly diatoms whose abundance corresponded to the season of most rapid ammocoete growth.. Adult and ammocoetes were not eaten by salmonid and other fishes of the Salmon River possibly because of a protective substance i n t h e i r skin. Transformation to adults f o r both species occurred i n the f a l l after at least 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. planeri was s i x years or more and that of E. tridentatus was seven years or more. Adult E. tridentatus parasitized trout i n E l s i e and Cowichan Lake to the greatest degree during the early spring and attacked salmon and other f i s h i n the sea during the summer months. x i i ACKNOWLEDGEMENT The author wishes to express his gratitude to the following persons: - to Professor P.A. Larkin f o r his encouragement, i n s p i r a t i o n , and supervision i n analysing re 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 for t h e i r c r i t i c a l reading of the manuscript. - to Dr. J. Briggs and Dr. C.C. Lindsey f o r t h e i r supervision, suggestions, and advice during the preliminary stages of the study. - to the I n s t i t u t e of Fisheries for providing 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 Fish and Game Branch personnel fo r t h e i r assistance in c o l l e c t i n g data: G. Hartman, D.R. Hurn, G. Vincent, and W. Fowkes. - to Doctors G. P i l e , D. Milne, and P. Wickett of the P a c i f i c B i o l o g i c a l Station at Nanaimo for data and suggestions. - to Dr. W. P f e i f f e r , M.A. Hafeez, and S.N. Ahsan f o r t h e i r h i s t o l o g i c a l assistance. - to the many fellow students for t h e i r assistance and suggestions. - to Frances L. Pletcher for her encouragement throughout the study and i n preparing the manuscript. - to Dr. J.R. Stein f o r her assistance i n i d e n t i f y i n g diatoms. - to W.E. Roberts for his assistance i n c o l l e c t i n g data. i v TABLE OF' CONTENTS LIST OF FIGURES v i LIST OF TABLES x i ACKNOWLEDGEMENT x i i INTRODUCTION 1 DESCRIPTION OF THE STUDY AREA 6 A. Physical description of the Salmon River 6 1. Mapping and stations 6 2. Drainage 6 3. Flow 11 4. Temperature 11 B. B i o l o g i c a l description of the Salmon River 15 .1. Plant cover 15 2. Aquatic plants 15 3. Animal l i f e 16 METHODS AND PROCEDURES 17 A. Co l l e c t i n g methods for ammocoetes 17 B. C o l l e c t i n g methods for adults 18 RESULTS AND A REVIEW OF THE LIFE HISTORY 20 A. Review of the taxonomy of B.C. lampreys 20 1. I d e n t i f i c a t i o n of adults 20 2. I d e n t i f i c a t i o n of ammocoetes 23 3' Nomenclature 25 4. Comparison of European and B.C. L. planeri 27 B. Adult L i f e 23 1. Duration of adult l i f e 23 2. Length of adults 31 3. P a r a s i t i c l i f e of E. tridentatus 36 4. Sex r a t i o and length of spawners 41 5. Fecundity of B.C. lampreys 45 6. Spawning of lampreys 51 a. Method of analysis 51 b. Spawning requirements 54 c. Sexual dimorphism at maturity 64 d. Prespawning a c t i v i t y 72 e. F i r s t sign of spawning 75 f. Nest building 76 V g. Combination rock l i f t i n g - d i g g i n g 7$ h. Digging action 7$ i . Courting behaviour 82 j . Spawning act - 84 k. Internal f e r t i l i z a t i o n 90 1. Length of spawning period 91 m. Communal spawning 94 n. Displacement behaviour 9$ o. Effect of temperature 101 C. Ammocoete L i f e 105 1. Method of hatching lamprey eggs 105 2. Embryonic and early l a r v a l l i f e 106 3. Hatching results 106 4. Burrowing and swimming action of larvae 10$ 5. C o l l e c t i n g emergent ammocoetes 109 6. Bottom type preference 109 • 7. Intestine analysis of ammocoetes 116 8. Protective nature of lamprey skin 120 9. D i s t r i b u t i o n of ammocoetes within stream 126 10. Relative abundance of ammocoetes 135 11. Burrowing behaviour of ammocoetes 13 S 12. Movement of ammocoetes i n burrows 140 13- Growth of ammocoetes 141 14. Entosphenus ammocoetes 146 15. Age determination and growth 14$ 16. Transformation of ammocoetes 161 D. Community relationship and mortality 167 DISCUSSION 170 SUMMARY OF SPAWNING BEHAVIOUR 16*3 SUMMARY OF LIFE CYCLES 184 CONCLUSIONS 186 LITERATURE CITED 190 v i LIST QF FIGURES Figure ' Page 1. P a c i f i c lamprey drying i n the sun at Moricetown on.the Bulkley River 5 2. Rivers and streams i n B r i t i s h Columbia where lampreys were collected and studied 7 3 • Colle c t i n g stations on the Salmon River 8 4 . Section of the Salmon River below station 1 10 5 . Pool area of the Salmon River 10 6. Mean weekly discharge and maximum water temperature (Salmon River, Station 1, 1960-61) 12 7. Mean weekly discharge and maximum water temperature (Salmon River; Station 1, 1961-62) 13 8. Mean weekly discharge and maximum water temperature (Salmon River, Station 1, 1962-63) 14 9. C o l l e c t i n g equipment 1$ 10. A standard scoop of substrate with some sand removed to.show the ammocoetes at the surface 19 11 . Method used to c o l l e c t ammocoetes i n the mud 19 12. Buccal disc and tooth morphology of the non-p a r a s i t i c lamprey L. planeri of the Salmon River 21 13. Schematic drawings of the buccal disc of the European and Salmon River L. planeri 21 14. Comparison of B r i t i s h Columbian and European Ammocoetes by area of pigmentation 21 15. Buccal disc and tooth morphology of the p a r a s i t i c lamprey E. tridentatus from the Salmon River 22 16. Schematic drawing of the disc and dentition of E. tridentatus from the Salmon River 22 17. Myotome number i n (a) ammocoetes (b) adults 24 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 Page 19. Length-frequency diagrams of adult (a) Lampetra planeri (b) Entosphenus tridentatus 33 20. Shows the size difference i n Entosphenus 34 21. Lamprey scar on the opercule of a 6 l b . pink salmon caught near Sooke 37 22. Rainbow trout g i l l netted in E l s i e Lake showing lamprey scar marks 39 23. Ventral view of in 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. planeri i n the Salmon River 1961-62 42 25' Experimental spawning tank 53 26. Spawning tank showing current and bottom arrangement 53 27. Experimental trough to test response of adults to current 5& 28. Experimental trough i n the stream, and laboratory tanks to test the preference of spawning adults f o r l i g h t 59 29. A pair of a c t i v e l y spawning L. planeri on the Salmon River i n bright sunlight 61 30. Lampetra spawning i n the shade of a log 6 l 31. Lateral view of the urogenital p a p i l l a of a male L. planeri and the surrounding structures 67 32. Dorsal view of the second dorsal f i n of L. planeri comparing the swelling present i n the female to no swelling i n the male 67 33« La t e r a l view of the swellings 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 35- Ventral view of the urogenital opening of E. tridentatus showing the p a p i l l a and the pseudoanal f i n 70 V l l l igure 3 6 . L a t e r a l view of the s w e l l i n g of the female at the p o s i t i o n s i n d i c a t e d by the arrows 37. L a t e r a l view 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 of the male E. t r i d e n t a t u s 38. Salmon River spawning a d u l t s from a communal nest 39. Lampetra removing rocks from a nest i n an aquarium 4 0 . Lampetra i n an aquarium nest d i s p l a y i n g d i g g i n g a c t i o n 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 Riv e r 42. Spawning sequence of L. p l a n e r i i n an aquarium 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 44. Communal spawning showing the p o s i t i o n of the t a i l of both sexes 4 5 . Spawning Lampetra showing the distance between the u r o g e n i t a l openings during the spawning, act 4 6 . Length of the spawning period at d i f f e r e n t temperatures f o r L. p l a n e r i of the Salmon River 47. C o i l i n g a c t i o n during communal spawning 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 4 9 . Experimental tank used to t e s t the bottom preference of l a r g e r ammocoetes $ 0 . Experimental trough to t e s t the bottom preference of l a r g e r ammocoetes 51. The p o s i t i o n that the ammocoetes burrowed i n the bottom of a trough w i t h a current of 1 foot per second at the surface 52. Epidermis of L. p l a n e r i ammocoete from the Salmon R i v e r , Dec. 28, 1962 IX Figure Page 53. Large pool where ammocoetes are deposited at station 1 127 54« Ammocoete.. beds and spawning nests at station 1 128 55. Station 4, Salmon River 129 '56. Station 1 pool, Salmon River 130 57. Length-frequency diagrams of L. planeri i n diff e r e n t habitats of the Salmon River on February 23, 1962. 132 56*. Length-frequency diagrams of L. planeri i n dif f e r e n t habitats of the Salmon River on September 9, 1962. 133 59. Length-frequency diagrams of L. planeri i n diff e r e n t habitats of the Salmon River 134 60. Concentration of ammocoetes per standard scoop i n di f f e r e n t bottom habitats of the Salmon River 136 61. Length-frequency d i s t r i b u t i o n of ammocoetes from certain streams i n B r i t i s h Columbia 143 6 2 . Length-frequency d i s t r i b u t i o n of ammocoetes from the Salmon River, 1960-1963 ." 144 6 3 . Growth of ammocoetes ( L. planeri) i n the Salmon River during the years 1960-62. 145 64. Length-frequency diagram of Entosphenus larvae, August 19, 1961. 147 6 5 . Length-frequency of Entosphenus larvae from the Nicola and Thompson Rivers 149 66. Separation of polymodal frequency d i s t r i b u t i o n s of L. planeri ammocoetes using p r o b a b i l i t y paper (Salmon River, Sept. 9, 1962) 151 67. Separation of polymodal frequency d i s t r i b u t i o n s of- L. planeri ammocoetes using p r o b a b i l i t y paper (Salmon River, February 23, 1962) 152 68. Separation of polymodal frequency d i s t r i b u t i o n s of E . tridentatus ammocoetes using p r o b a b i l i t y paper ( Thompson and Nicola Rivers, Aug. 19, 1961) 153 Figure Page 69. Separation of polymodal frequency d i s t r i b u t i o n of E. tridentatus ammocoetes using p r o b a b i l i t y paper ( Nicola River, Aug. 2, 1962) . 154 70. Growth curve of L. planeri from the Salmon River 156 71. Growth curve of E. tridentatus, Nicola and Thompson Rivers 157 72. Growth curves of B r i t i s h Columbia lampreys ( Nicola and Salmon Rivers) 158 73« Length-frequency diagrams of transforming larvae, ammocoetes and adults of Lampetra and Entosphenus 163 74. A comparison of the size and shape of transforming larvae of L. planeri 165 75. A comparison of the head of L. planeri 165 1 / x i 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 size of B r i t i s h Columbia lampreys 49 4. Analysis 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 River, July 25, 1962 110 6. Bottom type preference of emergent larvae from the Salmon River 113 7. Ammocoete b u r i a l rate i n the sand and mud in a trough suspended i n the Salmon River 115 8. Intestine analysis of ammocoetes from the Salmon River 118 9» Summary of p r o b a b i l i t y paper analysis of two c o l l e c t i o n s of L. planeri and E. tridentatus 155 1 INTRODUCTION A study of the l i f e history and d i s t r i b u t i o n of Lampetra  planeri (Bloch) and Entosphenus tridentatus (Richardson) was undertaken because of an almost complete absence of inform-ation concerning the biology of these two species i n B r i t i s h Columbia. Stomach analysis, bottom preference, d i s t r i b u t i o n within the stream, and a s t a t i s t i c a l analysis of the length-frequency data f o r the two species of lamprey were carried 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 , fecundity, spawning behaviour, and seasonal d i s t r i b u t i o n were also observed on the study stream during t h i s period. Duration of the various l i f e stages from egg to adult was attempted from the data collected. The ecological relationship between the various stages of lamprey growth and the other community members i s discussed as well as the significance of parasitica and non-p 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 carried out on the Salmon River lamprey population. This r i v e r drains delta 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 habitat 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. Preliminary spawning behaviour observations were carried out i n aquaria i n the laboratory as well 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 River , and the Big Qualicum River for comparison with the Salmon River populat ion. 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 , Big Qualicum, Stamp, C 0 wichan, Sweltzer, and Port John systems. Ammocoetes of t h i s species were co l l ec ted from the N i c o l a , Thompson, Tsolum, and Big Qualicum Rivers . The l i f e h i s to ry of Lampetra p laner i i n Washington State has been studied by Schultz (1930). A survey of L . p laner i and E. t r identatus was made i n the Cowichan River by Car l (1953)• Lampetra p laner i has been extensively 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 cycle seems to run through the groups. Lampreys are a s i g n i f i c a n t and in te res t ing vertebrate group because they represent the lowest form of vertebrate found i n fresh water lakes and streams as w e l l as being c lose ly re la ted to the oldest vertebrate f o s s i l forms- the Ostracoderms from fresh water S i l u r i a n and Devonian remains. They are d i s -t r ibu ted widely i n the temperate regions of the world , being found i n North America, A u s t r a l i a , New Zealand, Europe, and 3 Asia. Lampreys are not di 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 returning to r i v e r s i n the l a t e spring and f a l l . Lampreys have been classed as p a r a s i t i c or non-parasitic by Hubbs (1924), Zanandrea (1961), and Hardisty (1963), but some workers do not agree that lampreys are true parasites. Facultative ecto-parasite 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 thesis. The non-parasitic brook lamprey i s seldom seen. The strong swimming a b i l i t y and sucking buccal disc enable lampreys to scale v e r t i c a l dams, wa t e r - f a l l s , and gorges that present impassible barriers to other f i s h . The common species , Lampetra planeri and Entosphenus tridentatus, are distributed extensively i n the Fraser River system, Skeena River, streams of Vancouver Island, and i n many other major coastal r i v e r s . A t h i r d species, Lampetra ayresi (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 fresh 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 al.(1959). Renewed interest i n the biology of lampreys has occurred i n the l a s t ten years due to lamprey parasitism apparently being d i r e c t l y responsible for the removal of the lake trout population from the Great 4 Lakes o f E a s t e r n Canada. I n c i d e n c e o f p a r a s i t i s m on t r o u t i n Cowichan and E l s i e Lake on Vancouver I s l a n d has been r e p o r t e d 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 (D.R. Hurn- B r i t i s h Columbia F i s h and Game Branch- p e r s o n a l communication). T h i s l i f e h i s t o r y and p o p u l a t i o n a n a l y s i s o f t h e lampreys o f t h e Salmon R i v e r and o t h e r systems, w i l l p r o v i d e t h e b a s i s f o r f u r t h e r r e s e a r c h and f u r t h e r management of t h e p r e d a t o r . HISTORICAL AND COMMERCIAL VALUE OF LAMPREYS Fo r c e n t u r i e s t h e N a t i v e I n d i a n s of B r i t i s h Columbia have used lampreys as f o o d i n t h e smoked, s u n d r i e d , and s a l t e d form. I n d i a n s a t Moricetown F a l l s on t h e Skeena R i v e r ( F i g . l ) and a t L i l l o o e t on t h e F r a s e r R i v e r c a t c h lamprey by l i n i n g t h e i r t r a d i t i o n a l salmon d i p n e t s w i t h f i n e meshed webbing. The lamprey a r e e a s i l y scooped from t h e canyon w a l l s as t h e y 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 r e p o r t e d t h a t masses of lampreys formed mats a l o n g the w a l l s o f Hell's Gate Canyon and L i l l o o e t R a p i d s t o a depth o f at l e a s t a f o o t o f e n t a n g l e d b o d i e s . K i n g Henry I o f England enjoyed e a t i n g t h e p r i m i t i v e but t a s t y lampreys t o such 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 meal. L i t t l e o r no commercial use i s made of t h e lampreys o f B r i t i s h C o l u m b i a . A few European immigrants a t A l b e r n i c a t c h the a d u l t lampreys as t h e y m i g r a t e up Stamp F a l l s f i s h l a d d e r and canyon. The m i g r a t i n g f i s h are caught by hooks a t t a c h e d t o 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 l a r g e r ammocoetes a r e o c c a s i o n a l l y used as b a i t by t r o u t f i s h e r m e n because t h e y t 5 mainta in v igorous body movements f o r a l o n g t ime when b a i t e d on a hook. The Chinese community i n Vancouver ma in ta in t h a t ammocoetes are the best b a i t f o r s turgeon i n the F r a s e r R i v 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 the S e a t t l e area 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) repor ted t h a t at W i l l a m e t t e F a l l s , (Oregon) up t o 200 tons o f lamprey are taken f o r r e d u c t i o n purposes d u r i n g the annual s p r i n g m i g r a t i o n . A smal l canning o p e r a t i o n uses Petromyzon i n O n t a r i o to produce s p i c e d , smoked, and f l a v o u r e d d e l i c a c i e s . Great numbers of adu l t lampreys can be obta ined at w e i r dams i n the 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 water running over the boards . The lamprey c l imb these boards and f a l l i n t o baskets a t 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 the f u t u r e . F i g . 1 P a c i f i c lamprey d r y i n g i n the sun at Moricetown on the B u l k l e y R i v e r . 6 DESCRIPTION OF THE STUDY AREA Lampreys were collected mainly i n the Salmon River and adjoining streams and on Vancouver Island, as indicated by Fig. 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 gravel. Streams with a steep gradient and l i t t l e or no pool area are usually 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, less than one mile from the sea, may be occupied by lampreys as i s the case, for example, i n Roberts Creek. A. Physical Description of the Salmon River 1. Mapping and Stations See Figures 2 and 3« 2. Drainage The Salmon River drains delta and plateau farm and wooded area i n the Lower Fraser Valley (Fig. 2 and 3)« The drainage basin l i e s at an elevation of less than 300 feet. The drainage area from Jardine to the r i v e r mouth (Fig. 3) has been subject to periodic flooding 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 clay. This section of the r i v e r has stable banks and a mud bottom. Few lampreys are found i n t h i s section of the stream as i t contains no gravel areas for spawning and ammocoetes washed down by flooding are usually deposited further upstream. From Jardine to Coglan Creek junction the s o i l s are clay 7 l . 2. 3. k.. 5. 6 . 7 . o. Salmon River Scott Creek Whonock Creek Sweltzer Creek Smith Creek Robert's Creek Stamp R i v e r 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 Rapids . N i c o l a River . Thompson River . L i l l o o e t t Rapids . Bridge R i v e r Rapids . Fraser River , Alouette River River,Lake or Creek. LANGLEY Fig,. 2 Rivers and streams i n Br were collected and studied preys 8 FIG. 3. COLLECTING STATIONS ON THE SALMON R. loams underlain by dense clay (KeHey and Spilsbury 1939). Ammocoetes are very abundant i n the large pool areas of t h i s section 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 ( Fig. 4 and 5). The stream bottom types are shown' i n Table 1. Table 1 Salmon River Bottom Types (McMynn and Vernon 1954) Section of Stream Miles . Percent Total length of stream system 22.3 100 Length of stream with unstable banks and no tree cover 11.8 53-0 Length of semi-permanent portions 4.3 19-4 Length of permanent portion 18.0 80.6. Length of permanent stream with unstable banks and no tree cover 7. 5 33-6 Length of permanent stream with stable banks and tree cover 10.5 47.0 The section of the r i v e r from Coglan Creek junction to above station 5 consists of sand and gravel loams underlain with clays (Keely and Spilsbury 1939). A moderate gradient exists and 30 to 40 percent of the bottom consists of gravel and stones (McMynn and Vernon 1954). Small pool areas occur i n t h i s section of the stream where s i l t , sand, and forest debris are deposited.. Spawning was observed throughout t h i s section 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 station 1. The stream bottom between stations 5 and 1 i s semi-10 F i g . 5 Pool area of the Salmon River below station 1. X = areas where ammocoetes may be co l l e c t e d . 11 permanent as flooding i s continually s h i f t i n g i t s pos i t i o n . The lower t r i b u t a r y from station 7 to the mouth did 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 station 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 usually occurs between December and February. A maximum discharge of 720 cubic feet per second (Second-feet) was recorded on December 3 0 , 1962, at station 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 to 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 further. 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 station 1. Individual 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. F E B . MAR. APR. MAY J U N E J U L Y 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. MEAN W E E K L Y DISCHARGE AND MAXIMUM FOR THE SALMON RIVER (STATION I, 1961-62 ) WATER TEMPERATURE 15 usually occurs i n June or July and the lowest water temperature occurs i n January or February. B. B i o l o g i c a l Description of the Stream 1. Plant Cover The entire drainage area was o r i g i n a l l y covered with dense coniferous forest, except f o r a small flood p l a i n near the mouth. The land above the flood p l a i n was cleared for a g r i c u l t u r a l purposes during the l a s t half 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 heterophylla), Broad Leaf Maple (Acer macrophyllum), and Red Alder (Alnus rubra) were replaced by crops of straw-berries and hay. The r i v e r banks are l i n e d with Vine Maple (Acer  circinatum), B i t t e r Cherry (Prunus emarginata), Cascara (Rhamnus purshiana), Northwest Willow (Salix s e s s i l i f o l i a ) , Western Red Cedar and Red Alder. The undercover along the stream consists of Salmon Berry (Rubus spectabilus), Thimble-berry (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 Stinging Nettle (Urtica l y a l l i i ) . . 2. Aquatic Plants Sewage bacteria (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 variety of diatoms and some desmids were observed to 16 inhabit the r i v e r water throughout the year, as was evident from analysis 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 quantities 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 material decays at a slow rate, but offers a refuge and possible food source f o r larger 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 with t h e i r data. They found Ephemeroptera to be the most abundant group followed i n abundance by Coleoptera, Plecoptera, Diptera, Trichoptera, Annelida, and Planorbidae. They noticed (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 flooding period. Fresh water clams were p a r t i c u l a r l y abundant from station 2 to the mouth of the r i v e r . The crayfish (Pacifastacus leniusculus) i s abundant, but was collected only during the summer and f a l l , and occupies a habitat s i m i l a r to the lamprey larvae. 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 stickleback (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 trout (Salmo g a i r d n e r i i g a i r d n e r i i ) , cut-throat trout (Salmo c l a r k i i c l a r k i i ) , p r i c k l y sculpin (Cottus asper), and the largescale sucker (Catostomus  macrocheilus). METHODS AND PROCEDURES A. Co l l e c t i n g Methods for Ammocoetes Emergent ammocoetes were collected by using a modified Surber Sampler placed i n the r i f f l e area of the stream below a spawning loca t i o n . The sampler was modified by gluing a l i n e r made from a knotted nylon stocking into the c o l l e c t i n g mesh of the sampler. This produced folds and a very f i n e mesh so that the water pressure did not force the delicate bodies of the newly hatched ammocoetes through the mesh. The sampler was placed i n the stream and emptied every eight hours. Flat aluminum trays (25 mm. by 38 mm.) were f i l l e d with f i n e mud and placed i n various locations i n pools and gravel areas to catch ammocoetes that were being carried down-stream. The larvae buried into the mud of the trays and were counted at eight hour i n t e r v a l s when the trays were removed. The majority of the ammocoetes of a l l year classes were' dug from the bottom of the r i v e r with a sturdy scoop attached to a long handle (Fig. 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 (Fig. 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 usually 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% formalin. 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 larvae from bottom sediments. B. Collec t i n g Methods for Adults A portable 400 v o l t pulsating square wave dir e c t current e l e c t r i c shocker (0-L Electronic Shocker, Oceanic Instruments Inc.) was used once to c o l l e c t prespawning adults hiding i n the gravel at the end of large pools (Fig. 11). An eight foot siene was used to c o l l e c t the gravel 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 carried out. F i g . 11 Method used to c o l l e c t adults and large larvae 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 (Fig. 9-B) that was quickly drawn over the nest removing the lampreys and gravel. P a r t i c u l a r care must be taken on bright sunny days to move slowly but to perform the scooping operation quickly 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 Dentition The d i f f e r e n t i a t i o n between adults of Lampetra  planeri and Entosphenus tridentatus i s f a c i l i t a t e d by the presence of blunt degenerate teeth i n the non-parasitic Lampetra while the p a r a s i t i c Entosphenus has sharp rasping teeth (Fig. 12 and 1 $ ) . Figure 1$ shows the vari a t i o n i n the cusps on the l a t e r a l teeth of Entosphenus. The schematic drawings (Fig. 13 and 16) show the difference i n number and position by dentition that appears commonly i n the two Salmon River species. The supraoral lamella of Entosphenus has three cusps; Lampetra has only two, while the i n f r a o r a l lamella 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 dissecting microscope. The adults had to be skinned and stained with eosin on occasions when counting from external features was d i f f i c u l t . The count was taken between the l a s t g i l l c l e f t 21 F i g . 12. Buccal disc and tooth morphology of the non-parasitic lamprey L. planeri from the Salmon River. Supra-oral(2A) and sub-oral(2Bj lamella with the disc and l a t e r a l teeth removed. Saggital section!3) through the buccal disc showing the l a t e r a l teeth, each with two cusps (3C). SALMON RIVER FORM EUROPEAN FORM (REDRAWN ZANANDREA 1961) F i g . 13. Schematic drawings of the buccal disc of the Salmon River and European L. p l a n e r i . Fig . 14. Comparison of B r i t i s h Columbian and European ammocoetes of L. planeri by areas of pigmentation. 22 F i g . 15 Buccal disc and tooth morphology of the p a r a s i t i c lamprey E. tridentatus from the Salmon River. F i g . 16 Schematic drawing of the disc and dentition of E. tridentatus from the Salmon River. 23 and the anterior edge of the urogenital opening. There was a s i g n i f i c a n t difference i n myotome counts between the adults of the two species ( Fig.1,7 mean L. planeri 63.9 and E. tridentatus 66.9; T = 10.53, P <.001). This represents a higher myotome range 62-69 for L. planeri compared t o : a 60-65 range reported by Hubbs (1924) and Carl et al.(195$). 2. I d e n t i f i c a t i o n of Ammocoetes Identifying 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 right side and counts made under the microscope. Skinning was accomplished by making two p a r a l l e l cuts along the side of the animal from the l a s t g i l l opening to just past the vent. Then the skin was stripped from the side with forceps. Staining the ammocoete connective tissue with eosin helped in making accurate myotome counts. Vladykov (1955) reported that on the average ammocoetes possessed 1 or 2 fewer trunk myotomes than adults. Counts of myotomes are most d i f f i c u l t on adults. Adult Entosphenus do not increase t h e i r myotome numbers on reaching adulthood as i s common for 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 for the adults and ammocoetes from the Thompson-Nicola system (exclusively Entosphenus)and those of the Salmon River, a mixed population containing mainly Lampetra (90-95% of spawning adults). Myotome counts on 45 ammocoetes of t' Entosphenus (range 65 to 71, mean 67.5) showed a highly s i g n i f i c a n t difference from Lampetra ( range 59 to 65, mean 24 fl L A M P E T R A <K=62.3> 6 0 65 7 0 N U M B E R O F M Y O T O M E S FIG.I7A.M YOTOME NUMBER IN AMMOCOETES NUMBER O F M Y O T O M E S L A M P E T R A E N T O S P H E N U S FIG .I7SMYOTOME NUMBER IN ADULTS 2 5 6 2 . 3 ) T = 1 9 - 3 , P = .001, 9 5 df. • The separation of the individuals with overlapping myotome numbers was accomplished by comparing the areas of the ammocoetes covered by melanophores (Fig. 18). Vladykov . and F o l l e t t (1958) maintain that, " 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 contraction to make t h i s method consistent. 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 larger ammocoetes of the two species. Small ammocoetes do not show the same d i s t i n c t differences 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 Nicola, Thompson, and Cowichan Rivers. Four of the ammocoetes with higher myotome counts from the Salmon River ammocoetes proved to be Entosphenus when melanophores were observed (Fig. 17A). 3 . Nomenclature A key to Western North American lampreys appears i n Carl et al. (195$). The i d e n t i f i c a t i o n and nomenclature of Entosphenus tridentatus 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 possible from the myotome counts given. The nomenclature applied to L. planeri 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 description of the North Western Brook lamprey was attempted by Creaser & Hubbs (1922) and was based on the description of Regan (1911) 26 ENTOSPHENUS TRIDENTATUS NICOLA 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 g i l l s l i t LAMPETRA PLANERI SALMON RIVER 96 mm, 88mm. No clear area above 1st g i l l s l i t Melanophores extended below g i l l s l i t Fig. 18 Shows how the melanophore pattern can be used to distinguish large ammocoetes of E. tridentatus from L. planeri. ) 27 from specimens taken from Europe, S i b e r i a , and Japan. The name Lampetra planeri 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 with 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 applies i n Eastern North America (Berg, 1931)• However for the lampreys from Western North America the s p e c i f i c name planeri has been retained. A re-examination of the genus Lampetra would seem to be desirable. 4- Comparison of European and B r i t i s h Columbia L. planeri The number of cusps on the middle l a t e r a l tooth of the Salmon River L. planeri ranged from none to three well developed cusps (Fig. 12) . Three individuals 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 side, 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 for 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. pl a n e r i . The myotome number of the adult European L. planeri varied from 60 to 65 (mean 62.3) Vladykov (1955), while i t s ammocoetes ranged from 58 to 64 (mean 60.7). The Salmon River population had higher counts of myotomes, 61 to 65 (mean 63•4) for adults while the ammocoetes had 58 to 65 (mean 6 2 . 3 ) . The melanophore area of the head and t a i l of the European L. planeri ammocoete was greatly reduced compared to areas of the North American form (Fig. 1 4 ) . 28 There'seemed to be a greater degree of sexual dimorphism i n the European form than in the Salmon River form because dorsal f i n height, eye diameter, and buccal disc diameter showed only s l i g h t difference with sex compared to marked sexual, differences 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 disc with teeth, formation of functional eyes, development of two dorsal 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 physiological and morphological changes. From length-frequency data adult l i f e apparently starts a f t e r at least 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 least one year. Leach (1940) i s of the opinion that there i s a rest period p r i o r to metamorphosis, when the ammocoete does not grow i n length. Stauffer (1962) found evidence of a longer l i f e cycle than was indicated from length-frequency data when he allowed a Sea Lamprey population to go to extinction. A rest period has been found i n a l l cases examined experimentally. It i s highly l i k e l y therefore that the Salmon River population and other B r i t i s h Columbia lampreys are at least one year older than i s indicated from the length-frequency analysis 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 partly metamor-phosed female was obtained as la t e as A p r i l 29. The buccal disc was 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 ( l6-20°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 into the gravel during the winter and leave the gravel only when sexual maturity i s completed i n the spring. C o l l e c t i o n from the Salmon River of four adults nearing sexual maturity but s t i l l burrowed i n the gravel was accomplished by using an e l e c t r i c shocker i n May 1962. These specimens had just attained sexual maturity as one female had .not shed her eggs and her body was distended. When placed i n an aquarium, communal spawning started within 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 usually die within a week of laying 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 l i v e as long as two months aft e r spawning. 30 Entosphenus The Brook lamprey achieves sexual maturity immediately af t e r transformation, spawns and dies; but the pa r a s i t i c lamprey, Entosphenus, migrates to sea at the st a r t of adult l i f e . The migration to sea takes place during the spring 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 fishes upon entry to the sea or lake and develops a large abortive 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 Nicola 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 following transformation. Small mature adults apparently migrating downstream were collected on the i r r i g a t i o n screens of the Nicola River during August. From the size of adults attached to 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 parasitism begins during the spring and summer following migration to the sea or lake. No evidence exists on the P a c i f i c Coast for parasitism by the lamprey during the f i r s t year of adult l i f e but they possibly feed on species of f i s h that are slow swimming and bottom feeders rather than on salmonids which are preyed upon by large lampreys. The size of scar marks on hosts and the size of specimens collected indicate a further 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 lake l i f e . P r e c o c i t y i s suggested by small s i z e d members of the populations i n the Salmon Ri 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 occur one year i n advance of spawning. Applegate (1950) suggests that the Sea Lamprey of Eastern North America spends two years of a d u l t l i f e i n the sea. Recent d i v i n g observations by Mansuet (1962) suggest that the Sea Lamprey, upon migration to the sea, may spend the w i n t e r of the f i r s t year i n the e s t u a r i e s near the shore feeding on small bottom and shore f i s h e s such as the menhaden. Atrophy of the mid-gut and i n t e s t i n e occurs upon entry to f r e s h water, and no feeding occurs during the year preceding 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 rocks 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 c o l l e c t e d during December, 196l, at M e r r i t t on the N i c o l a River w h i l e the w r i t e r was t u r n i n g over some l a r g e boulders. A short migration to l o c a t e spawning g r a v e l i s suspected i n A p r i l to June, when o , the temperature r i s e s above 10 C (from observations on the Salmon R i v e r ) . Few a c t u a l observations of Entosphenus spawning have been witnessed and apparently no d e s c r i p t i o n s of spawning behaviour occur i n the l i t e r a t u r e . .2. Length of Adults Ammocoetes and a d u l t s were measured to the nearest mm., by p l a c i n g the animals over a p l a s t i c r u l e r and reading the distance from the t i p of the o r a l hood to the t i p of the t a i l . A shrinkage of 3 percent occurred a f t e r a period 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 after anaesthetisation 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 Fig. 19A). The.mean length i s 120.mm. for the Salmon River and 143.8 mm. and 167-2 mm. for the other streams respectively. Schultz (1930) collected 126 adults (mean 110 mm.) near Seattle, Washington. These.Lampetra are much smaller than any of the populations in B r i t i s h Columbia. Hardisty (1944) found considerable v a r i a t i o n i n the size of adults from diff e r e n t streams and even from d i f f e r e n t parts of the same stream for L. planeri i n England. He found a difference 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 (83-169 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 size represents mixed spawning classes as i s also indicated from the length-frequency data. Two or three modes may occur i n separate age classes. However n u t r i t i o n a l or environmental effects on length was indicated by the great range i n length i n L.planeri i n the Salmon River (Fig. 24). The upstream adults are s i g n i f i c a n t l y smaller i n length than the downstream individuals which suggests differences i n n u t r i t i o n . 33 100 120 KO 160 180 L E N G T H IN M M FIG.isA. LENGTH-FREQUENCY DIAGRAMS OF ADULT LAMPETRA PLANERI , 3 Q < U. o UJ CD D Z 20 25 •L i 25 NILE C R E E K 7. - 204 —i— 30 35 S T A M P RIVER X = 313 COWICHAN L A K E X = 284 537 SALMON RIVER 7 = 281 30 35 40 45 20 25 LENGTH IN CM FIG.198. LENGTH-FREQUENCY DIAGRAMS OF ADULT ENTOSPHENUS TRIDENTATUS 34 Entosphenus The Entosphenus spawning population on the Salmon River also shows a wide range i n size when compared to the migrating adults collected on the Stamp River. 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 variat i o n i n length i s from 193 to 450 mm. with a mean of 281 (See Fig . 16 & 19). Inadequate sample size from t h i s rather small percentage of the Salmon River lamprey population (5-10%) l i m i t s the conclusions that can be drawn, but there i s an indi c a t i o n from the histogram (Fig. 19) that two d i s t i n c t size groups may be present. I t i s possible that some individuals return from the sea prematurely Fi g . 20: Differences i n sizes of Entosphenus A. A distended 410 mm. specimen from Port John B. A 33O mm. migrating adult from the Stamp River C. A 183 spawning female from the Salmon River D. Metamorphosing adult from Nicola River E. Metamorphosing adult from Big Qualicum River 35 because they may migrate to the Fraser River or estuaries, while the- larger size 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 fishes 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 size group (Fig. 1 9 ) . The size of lamprey scars on whales (Pike, 1951) and from one large specimen (570 mm.) taken from the mouth of a fur seal many miles off Cape F l a t t e r y , suggests that larger lampreys go many miles into the open ocean. Carl et a l . (1959) suspect that a dwarf race of Entosphenus i s present i n the .Cowichan River system. An analysis of 6 specimens attached to trout 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 indicated from t h e i r gonads and i n t e s t i n e s . They possibly represent a land-locked race of lamprey that spends i t s entire l i f e i n Cowichan Lake and i s sim i l a r to the land-locked lamprey of the Great Lakes. However, one specimen 537 mm. i n length was collected attached to a log during June of 1961. On examination i t was determined that t h i s represented a migrating adult returning from the sea (Fig. 23). Carl (195.3 ) reported a large migrating run of Sea Lamprey that formerly ascended Scutt F a l l s i n August. No reports of t h i s large 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 recently impounded E l s i e Lake near Alberni (D.R. ,Hurn, personal communication). Hurn reported a 76 percent incidence of lamprey parasitism on the trout population i n t h i s lake i n May (Table 2 ) . His netting of trout showed an 36 increase of fresh lamprey scars during the spring and early summer. Recruitment from the sea has been cut off by the impoundment and a landlocked race i s l e f t to continue the cycle. The size of the scars indicate a dwarfed race of lamprey or immature size lengtk A simi 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 Hell's Gate on the Fraser, Moricetown F a l l s on the Bulkley, and Bridge River Rapids and Stamp F a l l s on Vancouver Island seem to 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 size of 217 mm. The reduction i n s i z e and fecundity of the landlocked lampreys of the Great Lakes gives added support to t h i s theory. The length of the adult Entosphenus of the Nicola-Thompson system was not determined. Recently transformed adults of mean length 122 mm. were collected during December 1961 and A p r i l 1962. One specimen 300 mm. long collected i n • December 1961 represented the wintering migratory year class which would spawn the following spring. Large adult size of lampreys i s suspected from the greater length of the ammocoetes collected and from the physical and chemical properties of the Nicola River system. 3• P a r a s i t i c L i f e of Entosphenus tridentatus Recently transformed Entosphenus feeds p a r a s i t i c a l l y soon aft e r transformation and migration to the sea or lake. Small P a c i f i c Lampreys were collected i n June attached to 37 Table 2. Incidence of lamprey scars on trout i n E l s i e Lake. D.R. Hurn, 1963, B r i t i s h Columbia Fish and Game Branch. Date No. of f i s h sampled Percent old & new scars • 1 Percent old scars Percent > new scars 20 May 59 47 76.63 2.13 74.5 6 May 60 80 57.5 27.5 30.0 6 June 60 24 66.67 29.17 37.5 13 July 62 110 40.91 13.64 27.27 3 A p r i l 63 19 52.63 21.05 31.58 5 June 63 117 15.20 8.77 6.43 Fig. 21 Lamprey scar on the opercule of a 6 l b . pink salmon caught near Sooke August 21. 3$ shore feeding and spawning herring 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 to September (Fig 21). Numerous reports of lamprey attached to herring bait 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 to the lakes where they begin to feed on the resident trout population. Hurn (personal communication) indicated a high incidence of parasitism (15-76 %) from analysis of trout bearing scars i n E l s i e Lake during the March to July period. In Cowichan Lake the period of greatest predation on trout extended from January to June ( Fig . 23 and Table 2). Wigley (1959) reported that Sea Lamprey of Cayuga Lake, New York, reached a peak of parasitism during August and September with an incidence of 66 to 70 % of the trout bearing wounds. He found the greatest number of lamprey scars on the largest trout, but found no preference by lampreys for trout of a certain s i z e . Analysis of covariance revealed that the lake trout with the greatest number of lamprey wounds are the thinnest, and smaller trout suffered"more severeweight loss than did large trout. Lampreys locate prey by vigorous swimming and orientation toward a chemical stimulus released into the water from the prey (Kleerkoper 195$) •> The chemical stimulus i s perceived by the olfactory organ located i n the lamprey's single n o s t r i l . The f i n a l l ocation 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> volt) 39 Fig. 22 Rainbow trout (Salmo ga 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 indicate old scars. B- fresh scar. Fig . 23 Ventral view of intestine (pin insertion) of adult Entosphenus. A- Spawning male, Nile Creek, June, complete atrophy. B- Female one year prior to spawning, Cowichan Lake, January, feeding reduced, atrophy started. C- Male, Cowichan Lake, January, a c t i v e l y feeding. 40 comes Into use 5-10 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 disc to be f i r m l y attached. A hole i s rasped through the skin and into the f l e s h by a toothed tongue and the blood and body juices are extracted by suction. A powerful anticoagulent i s injected that keeps the blood flowing, helps to corrode the f l e s h , and thus enlarges the wound (Kennedy 1956). Duration of Attachment Carl (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 trout, brown trout, char and coho salmon f o r a period of one day to several weeks. Kennedy (1956) reported that Sea Lamprey i n the Great Lakes remained • -attached to prey f o r at least one day to a week. Hurn (personal communication) found that Entosphenus i n E l s i e Lake attached most frequently below the l a t e r a l l i n e and posterior to the opercule (Fig. 22). Wigley (1959) analysed lamprey scars and found 49% i n the pectoral, 25% i n the prepelvic, 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 indicate 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 surviving and attacked f i s h are seriously 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 ov e r a l l sex r a t i o for the Salmon River proved to be nearly even 1.2:1 for 1960-1963 (Males/females see F i g . 24). Schultz (1.930). recorded the sex r a t i o at 2-32:1 for 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 larger proportion of females downstream, 1:2, and a larger proportion of males upstream, 2.5:1 (Fig. 24^). There i s also a s i g n i f i c a n t difference i n lengths between males (mean 113-4) and females (mean 126.8 t= 3-1 p =J>.0l) f o r the adults collected during the spawning season (Fig. 24A). Schultz (1930) found the opposite r e l a t i o n -ship, the males were larger than the females (means of 112 and 107.8 resp e c t i v e l y ) . The effects of sex and stream location are confounded on the Salmon River. The upstream individuals of both sexes are smaller and males preponderate, while downstream the animals of both sexes are larger and females are the more abundant sex (Fig. 24B, 24C, and 24D). Hardisty (1961) found no s i g n i f i c a n t difference between the length of the sexes for L. planeri i n England over a ten year period. These sex r a t i o s and differences i n size offer some food for speculation. The large size of the adults downstream suggests that there i s a greater growth due to a better 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 available to the larvae. The greater number of females i n the 42 O ID. DOWNSTREAM 100 120 14 0 O U P S T R E A M 5 X = 126.8 i r SEX RATIO 1.3:1 0* 7=113.6 100 110 120 130 140 LENGTH IN MM 100 120 140 160 LENGTH IN MM FIG. 2 4 A . L E N G T H DISTRIBUTION OF FIG. 2 4 B . L E N G T H DISTRIBUTION O F A D U L T S . S E X E S . in . CN-o O -z. m • 1961-62 a 1963 DOWNSTREAM in Ji ,_• P I , • l rJOL 110 120 130 140 150 UPSTREAM IJJL O z in. 100 110 120 130 K 0 LENGTH IN MM 100 DOWNSTREAM SEX RATIO U2 120 14 0 U P S T R E A M S E X RATIO- 2.5: 100 120 140 LENGTH IN MM FIG. 24 C. LENGTH DISTRIBUTION O F F I G . 2 4 D . L E N G T H DISTRIBUTION O F M A L E S F E M A L E S . FIG. 2 4 . L E N G T H - F R E Q U E N C Y DISTRIBUTION OF ADULT L. PLANERI IN T H E S A L M O N RIVER , 1961 — 6 3 . 43 downstream c o l l e c t i o n suggests a greater reproductive potential for the downstream population. This trend occurred i n three separate years so i t does not indicate sampling v a r i a b i l i t y . 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 adults held i n aquaria at d i f f e r e n t temperatures offer some explanation for the sex r a t i o . At low temperature (<O-0°C) the females are the aggressive nest builders and are active on the gravel, while the males are usually active for 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 early part of the season when the temperature i s cold. When spawning lampreys are transferred from a cold tank (3-10°G) to a warm tank (14-16°C) the behaviour changes. The male becomes the aggressive nest builder while the female spends more time away from the nest hiding under stones. Careful temperature analysis i n the stream correlated with sex r a t i o throughout the season and at various times of the day should prove rewarding. There was a two degree higher temperature i n the upper part of the stream i n 1963, which would indicate 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 and 1962. Upon more careful sampling during 1963 the upstream population was recorded spawning just as early, or e a r l i e r . Dead adults upstream and spawned out females indicate that the upstream population may have started 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 active i n cold temperatures than the males and would thus move to the upper gravel areas of the downstream area (station 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 adults (S-14GC) indicate that the males l i v e d f o r at least s i x weeks after spawning started while a l l the females died within 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 die f i r s t but males usually die within two weeks of c o l l e c t i o n . Therefore, behaviour of adults at diffe 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 effect the sex r a t i o of co l l e c t i o n s . Hardisty (1954) analysed L., planeri 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 diffe 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 for Petromyzon marinus. Greater l o n g i v i t y of males was suspected by the above workers as a possible explanation f or the greater number of males as the season progresses. Hardisty (1954) made weekly analysis of sex r a t i o throughout the season and found that 45 . the smallest proportion 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 c o r r e l a t i o n between the sex r a t i o and the r e l a t i v e abundance. The years,with the lower r e l a t i v e abundance were as s o c i a t e d w i t h a sex r a t i o of 1.8 or l e s s w h i l e 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 reported by Applegate (1950a, 1950b) for. P. marinus. Wigley (1959) found that when sea lampreys were abundant there was a higher proportion of males ( 3 ; 2 ) and i n years of 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 that the d i f f e r e n c e i n sex r a t i o may be caused by environmental c o n d i t i o n s as temperature 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 long ammocoete l i f e he considered the transformation year as being c r i t i c a l to the environmental e f f e c t on the sex r a t i o . Entosphenus Small sample s i z e of the adult's prevents drawing r e l i a b l e conclusions about the population. From the 11 a d u l t s c o l l e c t e d , 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 population s i z e according to H a r d i s t y T s theory. A sample of 12 migrating a d u l t s on the Stamp Riv e r revealed a 1:1 r e l a t i o n . 5• Fecundity of B r i t i s h Columbia Lampreys The number of eggs i n a one gram or l e s s s e c t i o n of the ovary were counted and weighed ( b l o t t e d d r y ) . Then the remainder of the ovary was weighed and the t o t a l number of eggs obtained by simple 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 Ri v e r makes estimation 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 pulation. Only two distended or n e a r l y unspawned females were found. These contained 1136 and 1900 eggs. However, samples from Cultus Lake (Sweltzer Creek fence) produced estimates of f e c u n d i t y between 2300 and 3000 while the. Hooknose Creek population had a s l i g h t l y higher f e c u n d i t y w i t h a mean of 2900 f o r the two populations (see Table 3 ) . H a r d i s t y ( I 9 6 0 , 1963) and Zanandrea (1961) recorded egg production at 1000-2000 (mean 1500) 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 higher number of eggs (mean 1$50) f o r L. zanandrea of T r e v i s o , ' I t a l y . Examination of spawned out dead a d u l t s from the Salmon R i v e r r e v e a l s very few eggs l e f t i n the body ( 1 - 7 ) . H a r d i s t y (196ljl9°3) suggests reduced f e c u n d i t y i n dwarf forms'is counterbalanced 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 separating L. p l a n e r i from L. f l u v i a t i l u s . He suggests that the brook lamprey evolved from the r i v e r lamprey by reducing i t s s i z e and egg number but t h i s i s balanced 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 mig r a t i o n . H a r d i s t y estimated the oocyte number of L. p l a n e r i ammocoetes at 5000-10,000; during metamorphosis the greater part of the ovary a t r i f i e s as only 1000-2000 eggs are l a i d . Svardson (1949) has suggested that reduced f e c u n d i t y i n f i s h e s i s accompanied by an increase i n egg s i z e , but t h i s does not occur i n lampreys 47 ( H a r d i s t y 1963)• Ha r d i s t y a l s o suggests that precocious sexual maturity 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) reported that i n f i s h and r e p t i l e s increased body s i z e r e s u l t s i n greater egg number r a t h e r than l a r g e r eggs. However, Lack (1954) suggested that the extent of the spawning journey that the female undertakes and the number of primary oocytes present i n the ovaries determines f e c u n d i t y . The large.lampreys w i t h the greatest number of eggs could conceivably represent the i n d i v i d u a l s that migrate the greatest d i s t a n c e , thus compensating f o r the greater m o r t a l i t y w i t h increased egg number. Egg s i z e of Lampetra i s not very v a r i a b l e i n the Salmon R i v e r . The Gultus Lake specimen was taken i n the Sweltzer Creek fence so complete maturity of the eggs cannot be determined, but the eggs were not completely f r e e from the ovaries which i n d i c a t e s immaturity. Entosphenus No mature unspawned Entosphenus were c o l l e c t e d from the Salmon Ri v e r but from s i z e alone a high p o t e n t i a l e x i s t s i n part of the p o p u l a t i o n . Analyses of unspawned Stamp Riv e r and Hooknose Creek populations 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 highest number being 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 s u f f i c i e n t -l y l a r g e to warrant a r e g r e s s i o n a n a l y s i s . Applegate found that the number of eggs produced increased q u i t e r a p i d l y w i t h increase i n t o t a l l e n g t h , but that increased weight was more 48 d i r e c t l y p r o p o r t i o n a l to egg production. Wigley (1959) reported a l i n e a r r e l a t i o n between body length and egg number f o r Cayuga Sea Lamprey. Ha r d i s t y reported a reduction i n egg number i n landlocked Sea Lamprey (mean 62,000, Vladykov 1951) from the parent Sea Lamprey that l e d an adromous l i f e (mean 171,000 eggs, Vladykov 1951)• B e t t e r c o l l e c t i o n s of unspawned' Entosphenus of the smaller s i z e groupings from the Salmon and Cowichan Rivers may r e v e a l from f e c u n d i t y data a p a r a l l e l to landlocked and es t u a r i n e races of P a c i f i c Sea Lamprey. The number of unspawned eggs i n dead spawned out specimens of Entosphenus from the Salmon River were 3 5-13 5 eggs. Applegate (1950) reported a 5% r e t e n t i o n of eggs at death. He n o t i c e d an increase i n the r e l a t i v e percentage of unspawned eggs i n females at the very end of the season i n Lake Huron Sea Lamprey. Thus a greater reproductive p o t e n t i a l e x i s t s f o r eggs that are produced by females at the beginning of the season. The egg diameter of Entosphenus i s very s i m i l a r to Lampetra (Table 3-) • The eggs of both species are e l i p t i c a l i n shape; immature migra t i n g Entosphenus possessing eggs th a t are one h a l f the s i z e of mature eggs. Ten eggs of 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 to neurula but development stopped at t h i s stage. This suggests that 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 observations, 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 took the spawning posture 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 areas and deeper water f o r 49 • Table 3. Fecundity and Egg; Size of B r i t i s h Columbia Lampreys Unspawned Entosphenus tridentatus Location Date Stamp River I t IT i t i t T t t t t t Hooknose Creek June 20, 1961 t t t t t t t t i t t t 1959 t t T t t t t t T t t t May t t Mean Unspawned Lampetra planeri Hooknose Creek t t i t T T t f t t t f t t t t Sweltzer Creek t t t t T t T t Salmon River Feb. t t i t T f t t 1957 T f TT t t T t May 30, . 1942 t t I t T f T f t t T f May 27, 1962 T f T t Mean T f Length 325 310 308 375 311 406 262 175 170 196 166 171 156 153 127 111 118 No. Eggs 18,600 10,100 30,500 35,400 15,500 106,100 24,800 34,400 3,700 3,300 3,700 2,900 1,700 3 ,000 2,900 2,300 1,100 1,900 Eggs remaining i n spawned out females Entosphenus . Salmon River Tt T t Lampetra Salmon River t t T f T f t t T f June 2, 1962 1962 i t t t 1962 A p r i l 20,1962 May 27, t f T t T f t f May 6, Tf T f 194 204 100 96 110 105 130 135 35 135 4 7 6 8 2 1 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 Date Length Width mm. Length mm. Salmon River June 3, 1962 110 1.07 . 1.12 tr tr May 27, 1962 111 1.09 ' 1.13 Smith Creek June 9, 1961 138 .98 • 1.05 Entosphenus Hooknose Creek May 1959 406 1.09' 1.24 Salmon River May 31, 1962 214 1.09 1.14 Tt tf . June 4, 1962 193 1.06 1.12 t! tf June 20,1962 204 1.09 1.17 Stamp River .69 immature June 20,1961 375 .57 51 nest bu i ld ing while Lampetra w i l l occupy an area downstream from that preferred by Entosphenus. The difference i n s ize 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 iable for some time as indicated 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 iav i s (I960), Lennon (1955). 6. Spawning of Lampreys •.(a) Methods of Analysis Observations of lampreys spawning under natura l conditions were made i n 1961 and 1962 at weekly i n t e rva l s when the stream was not f lood ing . 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 per iod. S t i l l water aquarium observations were under-taken i n 1961 and 1962 when 7 ga l lon 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 layer of gravel 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 east-facing 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 . ear ly summer they were removed from the window loca t ion to a table four . feet from the window to prevent excessive heating. . .• Running water tanks were established 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 that. The tank had glass sides, wooden ends, and a metal bottom (Fig. 25). A continuous current was maintained i n the tank (.2 to -35 feet per second) and with a flow of 300 to 400 cc. per second (Fig. 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 with gravel taken from the Salmon River. 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 inflow of water (5-7 cm. per sec.) was maintained o 0 i n order to 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 pictures were taken of the 1963 spawning, i n order to analyse behaviour; 35 mm. photographs were taken throughout the time to analyse the positions and actions 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 diffused and reflected l i g h t 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 difference between the two sides of the aquarium. 53 Fig. 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, outlet. .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 gravel from the na tura l spawning bed was placed i n the bottom of one . and sand i n the other. (Later the sand was replaced by f ine stones.) Observations of bottom preference for nest bu i ld ing were made. An experimental trough was also placed i n the stream with one ha 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 sunlight on a r i f f l e area with a current flow s i m i l a r to that of the actual spawning r i f f l e s . (b) Spawning Requirements of Lampetra  Matur i ty 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 for t h i s conclusion i s shown i n the fo l lowing two examples. On A p r i l 29, 1963, an immature Lampetra from the Salmon River was introduced in to a 16-20°C. tank containing grave l . The animal immediately burrowed in to the gravel 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 laner i used the tank for spawning but the immature specimen remained beneath the grave l . The specimen appeared to be a male when f i r s t introduced in to the tank, but after three weeks i t s abdomen began to swel l and dis tend, 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 ea r l y through the transparent and distended abdomen. 55 Two male Lampetra were collected 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 tank for observation. They remained burrowed under the rocks for the f i r s t three weeks but i n the fourth week they made exploratory swimming excursions around the tank and began to l i f t rocks and dig p e r i o d i c a l l y . They became more active and spawned with females that were introduced into the tank. One died on June 4, and the other was k i l l e d on May 27 as the viable sperm was used to f e r t i l i z e eggs. Spawning temperature and gravel were present i n each of the above instances but the animals did not mature and move from the gravel u n t i l t h e i r sex products and second-ary sex c h a r a c t e r i s t i c s were mature. In the Salmon River, the differences i n maturity date between individuals accounts for. the long spawning period- from A p r i l to July. Temperature Effects Brook lamprey of the Salmon River were observed spawning and laying eggs under laboratory and f i e l d conditions within 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 planeri i n the r i v e r leo. He recorded i s o l a t e d animals on the spawning s i t e at temperatures below 10°C. A marked r i s e i n numbers of animals occurred as the temperature rose above 10-11°C and showed a high degree of correlation with temperature. This behaviour was v e r i f i e d i n laboratory observations on Salmon River lampreys i n a cold tank (8°C ) where most animals hid beneath the gravel, but when the temperature rose above 10°C. a l l the animals 56 l e f t the gravel. In 1961 the f i r s t adults were seen i n May. However, the temperature was above 10°C, for some time before t h i s (indicated by Fig.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 sign 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 indicates flooding c l e a r l y shows that spawning probably started near the 1 0 t h of A p r i l . ( F i g . 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 condition. By analysing flow and temperature data f o r 1961 and 1962 i t i s possible to conclude that spawning could s t a r t i n the Salmon River as early 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 July. 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 adults were obtained with seining 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 station 1, and 11.5°C. at stations 4 and 6. When these spawners were dissected i t was found that some were spawned out, ~ especially 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 mid-April. Schultz (1930) found L. planeri 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. Carl (1953) reported Lampetra spawning i n Holmes Creek i n May. The Sea Lamprey prefers a much higher 57 temperature (18-2 l°C, ) for 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 for as temperature dropped the spawning d id 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 ses above 10°C. because the increased current prevents the adults . from occupying a pos i t ion on the grave l . . Seining over the gravel areas during f looding d id not produce any adults although adults were common on the same s t re tch of gravel two days before f looding occurred. Temperature and f looding condit ions i n 1962 indica te that spawners should appear on the gravel during the second week i n A p r i l . Current Preference A large trough f i l l e d wi th gravel 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 ig . 27)• A board over the end screen cont ro l led the current i n the tank. A current of 1 f t . sec. was maintained and 8 adults were introduced into the rear of the trough. The pos i t ion of the adults was observed af ter one hour. Then the current was increased to 2 f t . per sec. and the pos i t ion of the adults recorded again. The experiment was repeated with eight new adults introduced into 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 to test response of adults to current A current i s a requirement for spawning i n the stream habitat. In the Salmon River spawning always occurred i n gravel 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 related to depth of water over the nest since 8-15 inches i s the range of water depth observed (See Table 4)• In natural conditions current and correct depth of water are more essential than l i g h t to spawning requirements. However, the presence or absence of a current did not affect 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 consideration i n 1962 and 1963. Kennedy (1957) and Scott (1956-57) have also found that Sea Lamprey can spawn i n perfectly 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 large 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 in gravel 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, indications are that lamprey seek gravel over which a current flows. Current seems to function in mixing the egg and sperm during the release of sex products, and in insuring a ready supply of oxygen for the eggs i n the gravel. Shade Preference The trough (Fig. 28-1) was placed i n a r i f f l e area of the Salmon ^ i v e r on May 10, 1962, and the current was adjusted to 1.5 f t . per s e c . A large black p l a s t i c sheet was placed over half the trough and 9 adult lamprey were introduced Fi g . 23 Experimental trough i n the stream (l) and laboratory tank (2) to test the preference of spawning adults for l i g h t . A- s u n l i t section; B- shaded section. 60 into the downstream end ( l i g h t ) of the tank. The position of the adults 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 position of the lampreys was recorded two hours l a t e r (1400-1600 nr.). 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 gallon wooden aquarium (glass 2 sides, Fig.28-2) was set up i n a basement window and half of the aquarium was covered with 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 influence on the choice of nest s i t e . Spawning lampreys generally seek shaded areas i n the gravel for nest construction. However, many nest occupied by spawning adults were observed i n open r i f f l e s during bright sunlight (Fig. 29). Therefore other factors such as current, bottom composition, and water depth seem more important factors than sunlight. Laboratory experiments showed s i g n i f i c a n t l y that lampreys preferred the shaded area of the tank i n daylight. 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 Steffner (195$) state that bottom 61 Fi g . 29 A pair of a c t i v e l y spawning L. planeri i n the Salmon River in bright sunlight. The pair i s occupying a crude nest constructed between the larger rocks. Fig. 30 Lampetra spawning in the shade of a log i n the Salmon River. 62 c o n d i t i o n s are more important than l i g h t , They performed s i m i l a r observations to those above and found that 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 nest c o n s t r u c t i o n . In the r i f f l e nests of the Salmon River Lampetra are found i n both shaded and s u n l i t areas. These observations l e d to f u r t h e r stream observations and a trough experiment i n the stream where a l l spawning f a c t o r s were present. Ten spawning Lampetra p r e f e r r e d the shaded part of the trough when they were allowed to d i s t r i b u t e themselves f o r a two hour period. The g r a v e l , c u r r e n t , and depth of water were i d e n t i c a l to that of n a t u r a l r i f f l e areas. A black p l a s t i c cover was then- moved to the opposite end of the trough. 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 to the shaded area. This p a i r which had s t a r t e d to construct a nest remained on the g r a v e l i n the open s u n l i g h t and continued w i t h the nest c o n s t r u c t i o n . This suggests that nests that are occupied i n the sun are probably constructed 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 nest or h i d i n g beneath the rocks i n the nest 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 small and produced l i t t l e shade of i t s own, nests 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, nests were common •in open s u n l i g h t . On one occasion s i x communally spawning ad u l t s were seen t a k i n g refuge i n the shade of a l o g ( F i g 30). H a r d i s t y (1944) found that Lampetra showed a preference f o r spawning i n the shade and u s u a l l y b u i l t nests under a bridge . 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 bright s u n l i t nests, the animals are e a s i l y frightened 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 action. The animals i n the shade are not as e a s i l y frightened from the nest. Bottom Preference One half of the compartments of the trough (Fig. 27) were f i l l e d with sand and the other compartments were f i l l e d with gravel.. Six 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 for a one hour period. The position 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 position recorded after 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 gallon aquarium was f i l l e d to a depth of 3 inches with sand and the remainder of the tank was f i l l e d with spawning gravel from the Salmon River. The tanks were placed i n an east-facing basement window and two di f f e r e n t groups of 6 adults used the tank for 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 ingredient of the habitat for spawning lampreys. Lamprey pairs never spawned i n the sand area of an experimental.tank. On 64 occasion single individuals 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 int e n s i t y spawning behaviour s i m i l a r to the spawning act. However, two females released eggs when kept i n a sand-bottomed- 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 gravel over other bottom types. Scott (1956-57) reported that Sea Lamprey invariably choose a mixture of coarse sand, gravel, and small rocks over other bottom types for 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, gravel, and stones were placed i n the aquarium immediate stone moving and spawning •followed. Hagelin confirmed the same reaction i n L. f l u v i a t i l u s . Applegate (1950) showed a correlation between amount of spawning gravel present i n the stream and the number of spawning lamprey. L. planeri 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 si m i l a r spawning requirements to Lampetra. They appear to be less sensitive to sunlight but n nest construction i s l i m i t e d to a few si t e s i n the stream. During the 1962 and 1963 spawning, the same nest locations were used. (c) Sexual Dimorphism at Maturity  Lampetra Recently transformed lampreys can not be separated sexually on the basis of exterior morphology. The two dorsal 65 f i n s are separated i n the transforming adult and grow c o n t i n u a l l y together' as maturity approaches (Vladykov 1955)• The i n t e s t i n e reaches i t s maximum st a t e of degeneration at the ohset of spawning. No food 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 to spawning (Leach I94O). A f t e r spawning commences the d o r s a l f i n s , area surrounding the u r o g e n i t a l opening, and the buccal d i s c of both sexes may become i n f i l t r a t e d w i t h blood. These are some of the general 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 the adult stage. Zanandrea (1961) recorded neoteny i n I t a l i a n Brook Lamprey ammocoetes. This c o n d i t i o n was S i m i l a r to sexual dimorphism w i t h the growth of a pseudofin, transparency of the body w a l l but the eriddstyle arid naso-pharynx remained i n the l a r v a l - form. This c o n d i t i o n was never recorded i n the Salmon Riv e r p o p u l a t i o n . No exact time of sexual maturity occurred i n the Salmon Ri v e r p o p u l a t i o n , but the appearance of sexual dimorphism and maturity occurred throughout the spawning season. Hagelin (1959) found the p e r i o d between sexual maturity arid the appearance of sexual dimorphism was two weeks. He-observed decreases i n s i z e during 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 obtained w i t h an e l e c t r i c shocker i n May of 1962 revealed them to be i n the e a r l y a d u l t stage. Their 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 to two weeks i n the aquarium these animals 66 matured, developed secondary sex ch 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 collected i n early 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 ch a r a c t e r i s t i c s were mature. A l l recent research indicates that a l l spawning p a r a s i t i c and non-parasitic lampreys develop secondary sex c h a r a c t e r i s t i c s at sexual maturity. The old 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 history i s available (Zanandrea 1961). There appears to be no difference i n colouration between the sexes. Two colour phases i n the Salmon River population, one yellowish golden-brown, the other a grey-black phase on the dorsal surface, are not c h a r a c t e r i s t i c of either sex. A l l spawning adults can be distinguished from transforming larvae by the presence of yellow or brown pigment i n the f i n s (Zanandrea 196l). Male Characteristics Twenty male L . planeri (mean length 110.2 mm.) and twenty females (mean length 110.0 mm.) were selected at random from the Salmon River adult c o l l e c t i o n s for measurements and comparison of sexual c h a r a c t e r i s t i c s . The following external c h a r a c t e r i s t i c s are those that appear on a sexually mature male (Figures 31 and 32). 1. A slender urogenital p a p i l l a i s present i n a l l males with a range i n size from 5.6 to 0.15 mm. However different degrees of protrusion 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$) reported the maximum length i n the 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 are s l i g h t l y higher than females (1st. d o r s a l 3.8: 3.06, 2nd. d o r s a l 6.3: 6.03, males to females). The base of the second d o r s a l f i n i s not swollen as i s the case of the female ( F i g . 32). 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 diameter, yet Vladykov found a l a r g e r eye diameter i n European Lampetra males. 4. The o r a l hood of males i s l a r g e r than that of females ( x 5.73:5.13). 5. S l i g h t or l i t t l e hypertrophy was noted around the vent as described by Hagelin and S t e f f n e r (1958). 6. The t a i l of the male bends downwards while t h a t of the female bends upwards ( F i g . 34). F i g . 34 Displays the upward bend of the t a i l of females and the downward bend of the t a i l of males of L. p l a n e r i from the 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 Characteristics The following c h a r a c t e r i s t i c s appear on a sexually mature female: 1. A pseudoanal f i n appears posterior to the vent (Fig. 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 dorsal f i n i s markedly swollen at the anterior edge (Fig. 32).. The semitranslucent oedema often becomes f i l l e d with blood as spawning progresses. The swollen f i n i s alleged to serve as a stop for the male's t a i l as i t c o i l s around the lower body of the female and thus directs the sperms on the eggs during the spawning act (Hagelin and Steffner 1958). 3. The anterior edge of the vent i s usually swollen i n a s i m i l a r manner to the pseudoanal f i n . 4. The sucking disc 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 usually shorter. 6. The abdominal body wall becomes transparent and.distended so that 1 i n d i v i d u a l eggs can be seen within. However, spawned out or nearly spawned out females may have very slender bodies. 7. The t a i l of the female i s usually turned upwards and i s p a r t i c u l a r l y noticeable i n the well preserved specimens and l i v e animals. 8. The urogenital p a p i l l a of the female i s reduced i n size 70 F i g . 35 Ventral view of the urogenital opening of E. tridentatus showing the p a p i l l a (A) and the pseudoanal f i n (B). Salmon River specimen. Fig. 36 Lateral view of the swelling of the female E. tridentatus at the positions indicated by the arrows. Fig. 37 Lateral view (A) and ventral view (B) of the urogenital p a p i l l a of the male E. tridentatus, showing the absence of the ventral swelling. 71 (less than 2 mm.) and i s usually enclosed by a f o l d of swollen skin. Entosphenus Entosphenus possess the same major sexual dimorphic ch 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 usually a red brown colour while the females are a darker brown or grey colour. The female body wall never becomes transparent as i t does i n Lampetra. The urogenital p a p i l l a of the male i s much shorter i n length compared to Lampetra. The body i s usually very much distended in the unspawned female (Fig. 38A and 38C). Fig. 38 Salmon River spawning adults. 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 collected and observed during t h i s stage because lampreys burrow into the gravel and thus • become d i f f i c u l t to c o l l e c t by conventional seining 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 condition 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 into the gravel above a r i f f l e area of the Salmon River. These specimens were not captured when the area was dug over and swept with a seine the day previous. Two males were collected from' the f i s h fence at Sweltzer Creek i n 1963 i n early A p r i l . One female was collected from the Salmon River i n early May, 1963, by digging and seining at night. 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 condition during the winter and early spring. The animals appear to burrow into gravel areas at the lower end of large pools during the prespawning period. They seem to be inactive and are not seen unless disturbed. Lampreys appear to spend t h i s period i n dormancy while maturity develops. Collected specimens observed i n an aquarium burrowed beneath the gravel and were not seen u n t i l they emerged i n spawning condition with 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 distinguished from the females. 73 A s l i g h t migration i n the Salmon River i s suspected prior to spawning, from the muddy lower reaches to above station 1. No spawning gravel i s available below station 1 and the flooding conditions of the stream during the winter carries 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 station 1. One, mile above the station and at station 2 no adults were seen but spawning adults and adults moving upstream were captured on the gravel at station 1 (Fig. 3 ) . P. Wickett (personal communication), collected lampreys at the f i s h fence on Ni l e Greek from 1948 to 1954 and recorded movement of lampreys down the creek from A p r i l to July with the peak movement occurring i n May and June. These figures reveal some movement during the prespawning period but the greatest movement within the stream occurs with the onset of J. • spawning. Leach (1940) observed laboratory-held I . fossor to be semi-sedentary u n t i l January when some specimens did not bury themselves while others were seldom out of the sand u n t i l A p r i l . Leach measured seven individuals 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 to lack the normal spawning stimulus to spawn natu r a l l y , but the sex products proved viable when f e r t i l i z e d a r t i f i c i a l l y . Schultz (1930) noticed an apparent tendency for the males to appear on the spawning grounds before the a r r i v a l of 74 females 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 . Applegate (1950), Gage (1928), and Wigley (1959) maintained that males a r r i v e d on the spawning-area before the females, chose the l o c a t i o n , and s t a r t e d " t o d i g the nest. The females were observed to j o i n the males l a t e r and a s s i s t w i t h c o n s t r u c t i o n . The above authors suggest that there may be a form of t e r r i t o r i a l i t y set up by the males. Thus, the prespawning period i s g e n e r a l l y a time of l i t t l e a c t i v i t y that s t r e t c h e s from the end of transformation to the beginning of the f i r s t signs of spawning. This period i s from one month to two weeks i n duration as the exact time of completion of transformation and the beginning of pre-spawning i s extremely d i f f i c u l t to determine. Prespawning extends from March to June i n the Salmon Ri v e r and depends on the m a t u r i t y of the i n d i v i d u a l Lampetra. Entosphenus Less i s ' known about the winter l i f e of Entosphenus than Lampetra as' few have been c o l l e c t e d or observed during t h i s time. One specimen was dug from between boulders i n December on the N i c o l a R i v e r ; another was removed from the g r a v e l at night on March 15 from the Alouette R i v e r . Three adult s nearing spawning c o n d i t i o n (sperm a c t i v e ) were captured at the f i s h fence at Sweltzer Greek on the f i r s t of A p r i l . Thus a sedentary burrowed existence i s i n d i c a t e d during the greater part of the prespawning and w i n t e r period w i t h migration 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 observations of behaviour during A p r i l 75 prior to spawning, the males are more active at lower tempera-tures than Lampetra. Entosphenus spends part of the prespawning period resting attached to the bottom rocks or the aquarium glass while Lampetra spends more time burrowed i n the gravel, (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 usually seen hiding i n the shade or under rocks during t h i s early period, while l a t e r when spawning i s more intense they are seen on the gravel i n bright sunlight. 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 construction or "play with stones" was observed. Both males and females l i f t e d and dropped stones haphazardly without construction of a nest i n any one l o c a l i t y . There seemed to be considerable movement within the gravel area before nest construction was started. When adults i n the spawning or prespawning condition are introduced to an aquarium they burrow into the gravel f o r a number of hours. The f i r s t spawning signs involve the adult leaving the gravel and resting attached to rocks. Searching the aquarium and f r a n t i c swimming around the surface of the aquarium usually follow and rock l i f t i n g and digging by individuals occurs l a t e r . Individuals may leave the gravel for a short time to dig 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 gravel during 76 the darkness hours before actual spawning s t a r t s . Hagelin (1959) observed a similar 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 glides 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 for the more vigorous behaviour of actual spawning that i s to follow. The f i r s t signs o of spawning start when the temperature r i s e s to 11 C, IHardisty 1944 and' Schultz 1930) while the temperature for 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 less than 10 G. w i l l i n i t i a t e females to st a r t spawning while a temperature above 10°C- has a highly stimulating effect on males. (f) Nest Building Normal nest building by Lampetra i n the Salmon River o commenced aft e r the temperature rose above 10 C. but spawning o . and nest bui l d i n g was observed at a temperature of 9 C (low temperature for spawning) on A p r i l 24, 1962. However, the temperature had previously risen above the 10 to 11°C. apparently necessary to i n i t i a t e the action (Hardisty 1954). The male (above 10°C.) was the i n s t i g a t o r of nest construction and contributed at least two-thirds of the effo r t of construction. The female helped the male complete the nest aft e r i t had been started. She contributed much less to the endeavour especially a f t e r spawning had started, f or much of 77 her time was spent with her body draped i n the nest with oral hood attached to a rock at the edge of the nest. Nest construction involved three d e f i n i t e actions on the part of either 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 less than 3/4 inch i n diameter were removed to the side of the nest. Most often the rocks were removed to the downstream edge of the impression, but occasionally rocks were carried upstream or to the sides of the nest, a distance of usually not more than s i x inches. Hardisty also observed t h i s (1944). Rocks weighing up to 30 grams were r o l l e d or pried from the nest, but rocks less than 15 grams were removed easily 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)• Fig. 39 Lampetra removing rocks from a nest i n an aquarium, (a i s removed rock) 78 In an aquarium the nest was round but i n the stream i t was u s u a l l y wider than i t was long (See Table 4 f o r s i z e s of n e s t s ) . In 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 the stream he would often s t a r t / a nest, p a r t i a l l y complete i t , and then wander away to a nest occupied by a number of other lampreys. The f i r s t nest was completed l a t e r by another animal or group of animals. (g) Combination Rock L i f t i n g and Digging This act was performed by lampreys i n removing l a r g e rocks from the nest. The buccal funnel was attached to the rock, the body was arched i n a prying motion, and the t a i l performed vigorous swimming movements. The a c t i o n was so vigorous that sand and small stones were s t i r r e d up from the bottom of the nest. Hagelin analysed t h i s and found t h a t the swimming movements were at a frequency of f i v e or s i x per second. I f the rock was very l a r g e i t was r o l l e d or c a r r i e d along the bottom and out of the nest. The lamprey o c c a s i o n a l l y turned on i t s back or side to pry a l a r g e stone loose; i t s body would r e s t on the bottom. The muscular movements of the head dragged or r o l l e d the rock a short d i s t a n c e . On a number of occasions two lampreys were seen attached to one rock and removed i t from the nest but t h i s was apparently a chance occurrence r a t h e r than co-operation. (h) The Digging A c t i o n This a c t i o n f o l l o w e d when the nest reached a depth of one inc h or when, some of the surface stones had been removed. The buccal d i s c was attached to a l a r g e r stone at the edge of 79 Table 4. Analysis 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 f A B C Cross-section through a Lampetra nest. Depths tabled below. S U R F A C E CURRENT - ft./sec- H T E P O O L J " I F RIFFLE .Longitudinal section through a Lampetra nest. Depths and current tabled below. Water Depth i n inches. Current i n f t . per sec. A B C D E F . G H Lampetra A p r i l 20/62 15 15 12 15 13 13 15 1. 5 " 25/62 12 13 12 4 12 12 3 1. 6 May 20/62 12 13 11 5 . 11 11 5 1. 5 " 27/62 6 10 5 12 6 6 7 1. 5 June 10/ 62 9 12 10 6 8 8 7 1. 6 i t t t t t 9 • 10 9 12 9 9 9 1. 6 t t t t t t 9 11 9 10 9 9 10 1. 5 t t t t t t 9 10 9 7 9 8 6 1. 2 June 14/ 62 7 10 8 5 7 8 4 1. 2 t t t t t t 13 15 12 13 13 13 10 1. 0 June 22/ 62 10 14 11 18 11 9 24 1. 0 i t t t t t 7 8 7 9 7 7 5 1. 5 Mean 9.8 11.7 9.5 9.7 9.6 9.4 8.8 1. 4 Entosphenus A p r i l 20/62 16 17 11 21 16 6 22 1. 2-1.6 A p r i l 28/62 13 18 15 21 12 15 23 <1 ..6 (Abandoned). 80 the nest and while the animal was on i t s side the t a i l vibrated rapidly 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 fli p p e d out of and to the sides of the nest, thus making the nest deeper (Fig. 40). This behaviour was undertaken by both male and female but i n the stream at higher temperatures i t was more frequently peculiar to the male. Rock l i f t i n g can follow digging but usually digging immediately preceded the spawning act when the nest i s completed or aft e r spawning has started. Fig. 40 Lampetra i n an aquarium nest displaying digging action. ( 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 or anchoring the eggs in the nest. From observations i t i s apparent that the vigorous digging action also serves to move the sex products to the urogenital 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 posterior 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 actions, the size of the nest, and i t s location i n the stream. Table 4 shows the larger dimensions of the nest and F i g . 41 shows a cross section of an Entosphenus nest. A comparison between Salmon River lampreys taken from the nest and the nest stones i s shown i n Fi g . 38. A spawning pair 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 regularly every two to f i v e minutes throughout the observation period. Nest construction and digging was carried on between spawning acts with the-males contributing the majority 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 S U R F A C E C U R R E N T 1.6 f t . / s e c . R I F F L E POOL II 16 17 F i g . 41 Longitudinal section through a nest constructed by a pair 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 large rock from the nest, but as with Lampetra t h i s i s apparently a chance matter of both lampreys attaching to the same rock at. one time. (i ) Courting Behaviour This behaviour i s usually confined to the nest s i t e and i s most often exhibited by the male, but females do display a s i m i l a r behaviour. The male and the female are usually seen j o i n t l y building the nest. The female, just prior to release of eggs, rests i n the nest with her buccal disc attached to rocks at the upper edge of the nest while the male continues to dig 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 dig, r e s t , and undulate again. Usually just a f t e r digging, followed by a short r e s t , the male moves to the bottom of the nest and touches the female's body with his buccal disc and moves, with a " g l i d i n g - f e e l i n g " motion , up her body to the top of her head. Hagelin (1959) describes a courting 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 nest-constructing 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 courting c i r c l e s were not observed i n L. pla n e r i , nor was there any•violent shaking by the female i n the nest; Hagelin may have interpreted the digging behaviour as 83 shaking. However, a shaking behaviour was observed when the female was attached to the aquarium g l a s s . The Salmon River 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 to a male not on a nest. This was observed toward other females i n the nest at va r i o u s times, as i s shown i n F i g . 42A. This shows three females occupying one nest but no male i s present on the day which f o l l o w e d high communal spawning. The two outside females i n the f i g u r e are undulating and the centre female has completed a c o u r t i n g g l i d e up the female attached to the g l a s s . This method of attachment of a female to another lamprey was not as f o r c e f u l and only on rare occasions was there arching of the forebody or vigorous v i b r a t i o n s . However, when two females are allowed to spawn without the presence of a male they u s u a l l y both a t t a c h the buccal d i s c to the glass or a rock 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 touching. Eggs were observed being released 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 time. 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 the rubbing of the body of one sex a g a i n s t , under, or over the body of another. This apparently tends to s t i m u l a t e the l e s s r e c e p t i v e partner i n t o a c t i v i t y , or i t may increase the general p i t c h of spawning a c t i v i t y of a communal nest.. A s i m i l a r behaviour was observed when one male had j u s t dug a nest but no females were to be found on the g r a v e l . Here the male went to the corner of the tank where the other a d u l t s were and burrowed under the rocks., t w i s t i n g h i s body about and against the others, thus apparently 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 action of the male i s very pronounced. The female courted or glided over the male only on one or two occasions. Usually spawning followed the f i r s t or second courting glide of a male over a female. The buccal disc 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 building only. No spawning actually took place during the observation period, (j) Spawning; Act A few courting movements immediately precede spawning. Here the male glides and fee l s up the female's body to a position above her buccal disc. He attaches his buccal disc to the top of her head (Fig. 42C) and arches his forebody. This i s followed'by the same behaviour from the female,, plus undulation of her body. The male twists his t a i l around the body of the female and both lampreys vibrate vigorously. Both lampreys stop vibrating and the male relinquishes his head and t a i l hold on the female (Fig. 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 action of the vibrations may be so vigorous that the rock to which the female i s attached i s pulled 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 into the loose sand, or against i t i n a v e r t i c a l position, at the bottom of the nest 35 Fig. 42 Spawning sequence of L . planeri i n an aquarium. A- females undulating i n nest waiting 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 twists his t a i l around her body, both vibrate and release sex products. D- male releases the head hold, both stop v i b r a t i n g . 86 as the eggs and sperms are released ( F i g . 43A, 43B, 43C). The fo r c e d v i b r a t i o n s cause the sand i n the nest to be s t i r r e d up i n a cloud. The eggs, heavier than water, are adhesive and become attached to grains of sand which sink to the bottom of the nest and are covered by the cloud of sand. When the nest was examined a f t e r a spawning a c t , no eggs could be seen at the s urface. The p a p i l l a of both animals may be completely buried i n the sand so that the eggs are a c t u a l l y r e l e a s e d 1 below the surface of the nest bottom ( F i g . 43A, 4 3 c ) . The t a i l p o s i t i o n of the female i s i n a v e r t i c a l plane ( F i g . 45) which i s q u i t e d i f f e r e n t from the p o s i t i o n of d i g g i n g , and the sand i s not sucked from the nest as i n the l a t t e r case. The i n t e n s i t y of the v i b r a t i o n s i s greater i n the spawning a c t than i n the digging a c t i o n . More than one p a i r of lampreys have been observed i n the spawning act at one time..One male has been observed spawning w i t h two females simultaneously. The male grasps one of two females that are undulating side by s i d e ; he throws h i s t a i l around one female that he has attached to and begins to v i b r a t e , as do both females. I t was not seen whether both females rel e a s e d eggs or not. Two males were a l s o observed to grasp the same female at the same time. Both grasped her on the head and wrapped t h e i r t a i l s around her body as i s charac-t e r i s t i c of the paired behaviour. A l s o , the males arched t h e i r bodies and v i b r a t e d v i o l e n t l y , w i t h release of sex products. There was no evidence of p a i r bond formation as males and f e -males spawned f r e e l y w i t h any partner of the opposite sex tha t 87 was available a f t e r the required physiological and behaviour s t i m u l i . 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 did not prove to be true for L. planeri or E. tridentatus i n the Salmon River. These males appeared to approach the female from which-ever side was convenient (Fig. 43 & 4 4 ) . More approaches were from the right 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. After each spawning by a pair there i s a short rest period during which the female usually rests i n the nest while the male usually leaves the nest f o r a short time. He usually 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 resting beside the female or attached to her. When the male'returns to the nest he starts rock l i f t i n g again and the digging motion. The nest i s usually enlarged i n an upstream d i r e c t i o n ; the eggs deposited are not disturbed by further spawning. The sequence of spawning, rebuilding the nest, and courting can be predicted and analysed with precision as a series of steps. Active spawning f i r s t takes place at in 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 after the major depos-i t i o n of eggs. Most of the eggs from one female are l a i d within 12 hours. After 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 position taken by the male i n grasping the head of the female, tf and C- three adults spawning at once. 89 Fig. 44 Communal spawning showing the position 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 dies. However, active spawning has not been observed very frequently because females with egg-swollen bodies are seldom seen. Spawned out and partly spawned out females are quite commonly observed spawning i n the f i e l d and i n the laboratory. This tends to indicate that the i n i t i a l and most active spawning takes place at night early i n the season. Entosphenus The actual spawning, as nest building, was more intense for 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 disc or head leaving tooth impressions from his sharp teeth. The vibrations that follow 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 into the cloud of sand p a r t i c l e s . and small stones. It 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) Internal F e r t i l i z a t i o n Much controversy exists as to whether or not intromission 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 position of the bodies during the spawning act (Fig. 42D, 44D, and 45). The farthest distance posterior that the t a i l of the male can stretch, yet s t i l l e ncircle the female's body, i s to the second dorsal f i n swelling. When the t a i l i s wound 91 in t h i s position the urogenital openings are s t i l l several centimeters from each other. This i s so i n both Lampetra and Entosphenus (Fig. 45, distance A). Intromission does not occur in B r i t i s h Columbia lampreys. Fig. 45 Spawning Lampetra showing the distance (A) between the urogenital openings during the spawning act. (1) Length of Spawning and Post Spawning Period It 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 possible 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 within 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 temper-ature (Fig. 4 6 ) . Usually less than ten eggs remained i n the body cavity 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 d i f f e r e n t i a t e d 92 80 70 60 50 c n Q O g cc £ 3 0 o z z < 0. U)20 u. o 5 10 DYING PERIOD MALES FEMALES MEAN \ \ n 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 within t h e i r bodies. Hagelin and Steffner (1958) reported that a l l r i v e r lamprey died about one week af t e r the l a s t eggs were deposited These researchers a t t r i b u t e death to a long f a s t i n g period pr i o r to spawning and a rapid use of energy during spawning. Numerous dead adults i n a spawned out condition were collected from the 20th. of March to the f i r s t week i n June from the Salmon River. A l l Salmon River lampreys kept i n aquaria died. The spawning period, and post spawning period for L. planeri from the Salmon River extended from the middle of A p r i l to the second week i n July. Animals were continually reaching maturity and dying throughout t h i s period. Dying and spawned out adults are characterized by marked reduction i n the abdomen diameter, fading and blotched colouration, and blood f i l l i n g the tissues of the f i n s , buccal disc, and region of the vent. A.number of dying adults have been observed going through rapid twisting movements and convulsions. The bodies of dead lampreys are covered with .fung within 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 to extend from A p r i l 20 to June 22 during 1962 according to specimens observed on the Salmon River. N i l e Creek specimens were caught i n spawning condition as l a t e as the f i r s t week i n July while spawning 94 movement was recorded as early as March from 1948 to 1954. Mattson (1949) reported Entosphenus spawning on the Willamette River, Oregon, i n June and July. Aquarium spawning and holding experiments were not carried out for 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 function and sig n i f i c a n c e . This behaviour of L. planeri has usually been observed during the beginning of the season or when a number of ripe animals have just been introduced into an aquarium. Six communal spawnings have been observed i n the stream during A p r i l and early May,' but none were observed during June or early July. This may be due to a decrease i n the density 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 usually much mobility within the.group, and when communal spawning was observed for a number of hours, the group broke up into three or more groups, each spreading out to neighbor-ing nests with spawning occurring i n each group. Ten minutes l a t e r the majority of them were back -in the f i r s t communal nest. There seemed to be some rhythm of spawning where two or three pairs 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 nest c o n s t r u c t i o n and enlargement of the nest between spawnings, and the females u s u a l l y take a l e s s a c t i v e part i n the pro-cedure. Communal spawning represents the highest a c t i v i t y l e v e l i n spawning which occurs f o r a period of one day or l e s s . A p a r t i c u l a r behaviour i s a s s o c i a t e d w i t h communal spawning that has never been reported before. That i s the c o i l i n g of e i t h e r a male or female around a spawning p a i r or 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 ) . This behaviour was examined w i t h the a i d of a motion, p i c t u r e and i t was concluded that i t may serve to bind a group of s t i m u l a t e d bodies to r e l e a s e sex products at one time, but whether or not the c o i l i n g a d u l t d i d r e l e a s e sex products i s not known. However, the c o i l i n g i n d i v i d u a l was seemingly sti m u l a t e d by the v i b r a t i o n s . I t could serve to hold the sex products together and ensure f e r t i l i z a t i o n , or i t may be simply 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 of a number of h i g h l y s t i m u l a t e d animals when one p a i r sets o f f the t r i g g e r mechanism of the spawning act. I t i s suspected t h a t . d u r i n g communal spawning a chemical r e l e a s e r s t i m u l a t e s lampreys to congregate at a communal nest. A r i p e unspawned female was introduced i n t o a tank c o n t a i n i n g four males and she was removed a f t e r a f i v e v minute stay. The presence of the female apparently caused the males to become very a c t i v e and they l i f t e d rocks and dug f o r a two hour period a f t e r the female was removed from the tank. Ripe unspawned females seemed to be always present i n the 96 Fig. 47 C o i l i n g action during communal spawning. A male or a female c o i l s around the spawning pair ( centre of each p i c t u r e ) . 97 communal nest. This suggests that females may give off a chemical releaser that congregates a number of lampreys to one nest for communal spawning. Communal spawning has been recorded for P. b r anch ia 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 nd iv idua l s per nest for Ichthyomyzon greeneyi. Schultz observed nine L . p laner i i n a communal nest i n Washington State near the s tar t of the spawning season. Dendy and Scott (1953) reported from f i v e to twenty lampreys i n a communal nest for Ichyomyzon gagei but they observed great va r ie ty i n numbers. Entosphenus Communal spawning was observed i n the Salmon River on one occasion when two large Entosphenus ( larger than 5 5 0 mm.) were seen i n one nest wi th three smaller i nd iv idua 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. Later d i ssec t ion revealed the animals were i n a spawned out condi t ion . The difference i n s ize between the two s ize ranges seemed to have no effect on communal spawning. A large female and a small male were co l l ec ted and spawned a r t i f i c i a l l y the fo l lowing day. The few < eggs that were obtained hatched i n the laboratory . Communal spawning does occur i n Entosphenus but usual ly the population on the Salmon River was so small that i n some years only pairs or s ingle i nd iv idua l s were c o l l e c t e d . 98 (n) Displacement Behaviour Spawning "displacement" behaviour occurs most frequently "when a central nervous mechanism has been stimulated but cannot use i t s normal outlet because the pa r t i c u l a r a c t i v i t y i s not possible." (Baerends 1957). In lamprey spawning behaviour there i s a normal series of steps that each animal goes through before the sex act. I f the, animal starts spawning by proceeding through one or more steps, as digging a nest, but i s prevented from completing the series,then a dif f e r e n t "displacement" behaviour i s observed. This "displacement" behaviour i s quite d i f f e r e n t from the normal sequence of spawning behaviour. It usually takes the form of reverting to a lower step of the normal series, when the other partner i s either 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 phys i o l o g i c a l l y ready to spawn yet the other does not complete the necessary response when the sign stimulus i s applied by the other partner. The energy i s usually channeled into an action that i s s i m i l a r to, or reverts to, early spawning behaviour. One form of displacement behaviour occurs when a single male or female has completed nest construction alone and no partner of the opposite sex i s present i n the nest to complete the spawning act. The i n t e n s i t y of digging i s usually 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 his buccal funnel up the animal's body. I f the 99 receiver i s a male he w i l l move away from the advancing male with quick swimming and wriggling motions. If the receiver 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 to spawn. I f the female i s not ready to spawn she w i l l remain burrowed or attached to the rock. The male responds by continually courting or g l i d i n g over her body with f e e l i n g motions with the buccal disc (Fig. 42B). On a number of occasions the male attached his buccal disc to the head, or brachial region of the female and swam or pulled her to the nest. Two spawned out and nearly dead females were observed being carried by the male to the nest. Once at the nest, the male proceeded to court and stimulate the female f o r ten minutes. The male attached to the female's head and wrapped his t a i l around her abdomen but the female did not respond with the undulations or vibrations of normal spawning. The i n t e n s i t y of the male's courting and attachments increased u n t i l the male went through the vibrations of spawning and t a i l t w i s t i n g with sperm release without any female response or release. This continued for one hour u n t i l the female f i n a l l y died, but the male continued to carry the female on to the nest and around the tank. The male l e f t the dead female and burrowed deeply into the gravel 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 to construction of the nest by rapid digging. Females were observed "searching" for a male aft e r completing nest construction. 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 (Fig. 48). Males usually responded by returning 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 act. Fig. 4 8 A female courting a male by g l i d i n g along his body. Females ready to spawn were observed courting other females by g l i d i n g up t h e i r bodies or attaching to the head of the other female and undulating the body. On one occasion one female arched the brachial region and vibrated rapidly 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 rapidly and close together i n the sand. Females ready to spawn and unable to arouse a male l i e f or long periods with t h e i r bodies curved i n the nest and undulating slowly. Occasionally the female w i l l dig up the bottom of the nest, l i f t rocks or attach to the glass of the tank and vibrate her 101 body rapidly as i n the spawning or digging action. 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 to court other males but the receiver always moved out of the gravel quickly. Hagelin (1959) describes t h i s action as one male r e p e l l i n g the other from the nest but i t seemed more an action 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 for a week immediately -became active and started digging and rock l i f t i n g when a female was introduced into the tank f o r a. short period. (o) The Effect of Temperature on Spawning  Effect on Behaviour Three tanks were set up to test the effect of diff e r e n t temperatures on behaviour. The following temperature ranges were established i n the three tanks: 8-10°C., 11-15°C , and 16-20°C . The two cold tanks were arranged with chlorine-free 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 dig nests a f t e r the f i r s t day of relocation 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 introduction as ripe females were present. Nest construction was usually i n i t i a t e d by the males with the females off e r i n g some assistance a f t e r the nest was started. •102. The males usually l e f t the nest f o r short periods after 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 into the gravel for the f i r s t day i n the 11-15°C. tank while the females rested attached to rocks or the aquarium glass. 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 gravel on the second day for short periods to help the females with nest construction. 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 displayed 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 aft e r introduction. Paired spawning and nest construction 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 condition and showed no more spawning action u n t i l death. The remaining males exhibited displacement behaviour af t e r the active females died. The males remained hidden under stones i n the coldest tank (8-10°C\) for two weeks aft e r introduction. Females hid under rocks for the f i r s t week but then they began to take periodic exploratory excursions around the tank. Occasionally nest construction was started by females during the second week. At the end of the second week a male occasionally l e f t the gravel to spawn with females that were a c t i v e l y occupying and digging nests. Females exhibited courting and displacement 103 spawning behaviour toward both males and females at t h i s time. Communal spawning was observed and filmed on the 1 4 t h . day a f t e r introduction 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 shortly. The females i n i t i a t e d . t h e nest building 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. After 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 after each spawning act or c o i l i n g action while the males remained i n the nest. A l l the females returned to the nest at regular i n t e r v a l s to dig and spawn. Active 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 into hiding again and the ripe females had released most of t h e i r eggs. Paired spawning was observed for the week following communal spawning with displacement behaviour being displayed very frequently by the females. L i t t l e digging and no spawning was observed during the 1 2 - 1 6 of May for the males and the females i n the cold tank. Two of these ina c t i v e males and females were removed from the cold tank and placed i n cold water that was allowed to warm gradually to room temperature (16-20°C ) . The two males became very active 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 to dig two separate nests. Spawning was observed immediately upon nest completion and for the next day. The males l e f t the nest after each spawning act while the females remained i n the nest. However, the females were i n a spawned out condition during the second day and did not have much energy to contribute to spawning during t h i s time. Both females died the second day aft e r transfer to the warm tank. Displacement behaviour was frequently displayed, between the two males and between the males and the dying or dead females. On the second day the males were returned to the cold tank. Their active behaviour stopped immediately and they burrowed into the gravel for the next two days. The females i n the cold tank were nearly a l l dead afte r one month from c o l l e c t i o n ; only occasional digging or spawning was observed. The males displayed frequent displace-ment behaviour a f t e r the females died. Periodic active swimming at the surface was observed at intervals- as was hiding i n the gravel. After 50 days from introduction 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 effect on reducing the a c t i v i t y and changing the behaviour of the lampreys. Effect on Length of Post Spawning Period 'Hardisty (1961) and Zanandrea (1961) suggest that Brook Lamprey die 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 laboratory tanks at three di f f e r e n t temperatures and the date of death was recorded for each i n d i v i d u a l (as described above). The s i x females kept at the coldest temp-erature (8-10°C.) died from 14 to 36 days af 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 af 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 af t e r c o l l e c t i o n (Fig. 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 for 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 (Fig. 4 6 ) . C. Ammocoete L i f e 1. Method of Hatching Lamprey Eggs Lampetra eggs were collected from the gravel of the spawning tank i n 1962, and placed i n nylon cloth 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 ci 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 gravel. In 1963, e g g 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 fi v e - g a l l o n glass aquarium (16-18°C temperature), and i n a 15°C. thermostatically controlled f i f t e e n - g a l l o n plywood tank. 106 A i r stones were supplied to the baskets at each temperature and f i v e days after hatching, a one-inch layer of recently collected Salmon River s i l t was added to the baskets. Obser-vations of hatching time, absorption of yolk sac, and behaviour of young ammocoetes were recorded. 2. Embryonic and Early Larval 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 rapidly i n fresh 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 af 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 rapidly i n lamprey eggs, the b l a s t u l a forming during the f i r s t three days (Piavis I960, Hardisty 1957). Piavis (I960) describes 18 stages of the sea lamprey embryo before i t developed into a larva at 33 to 40 days. The development of Lampetra embryos was compared to the stages and description outlined by P i a v i s . 3. Hatching Results The 1962 Lampetra eggs hatched.after 15 days at l6-20°C , and at 3 0 days the larvae were a c t i v e l y burrowing into the bottom of the containers. The recently-hatched and older larvae were very sensitive 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 bright 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 sensitive to l i g h t and that the animals show a photokinesis. This i s a locomotory reaction to l i g h t , bearing no d i r e c t i o n a l r e lationship to the source of stimu-l 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 into the mud to 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 attained a length of 18 mm.. In 1963 a better control of temperature was obtained and eggs of both Entosphenus and Lampetra were hatched. Lampetra hatching started a f t e r 13 days at 17°C and a f t e r 15 days at 15°C. . Hatching was usually complete aft e r 3 days from the f i r s t sign of hatching. Entosphenus eggs started hatching af 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. Naturally spawned eggs were hatched at 8-9°^ i n 25 days. Carl (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 English 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 success-f u l l y i n 3-5°C conditions after 8 weeks. The stages of embryonic development of Entosphenus and Lampetra were very s i m i l a r to that described by Piavis (I960) for 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 controls lamprey egg hatching time and development, but there seems to be only s l i g h t differences i n hatching time and development between the two species. The developing Entosphenus and Lampetra embryos, one week after hatching, became more sensitive to l i g h t . The yolk i n the i n t e s t i n e began to disappear after the second week from hatching (20-35 days). The mouth became connected to the. digestive t r a c t and the branchial 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 (Piavis I 9 6 0 ) . 4. Burrowing and Free Swimming Action of Larvae Observations on larvae i n the laboratory showed that they began to burrow after 20 days, but 'in the stream they are already burrowed i n the gravel. In the stream, the larvae leave the gravel a f t e r two or three weeks from hatching, are carried downstream by the current and are deposited i n the f i n e mud of pools. Gage (1928) believed that the larvae leave the gravel af 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 circadian 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 night. Kleerekoper et a l . (1962) showed that ammocoetes exhibit a diurnal p e r i o d i c i t y within the mud 109 and at the mud surface. 5. C o l l e c t i n g Emergent Ammocoetes Below Spawning Nests Collections were made i n the Salmon River to determine when newly-hatched larvae leave the gravel and migrate down-stream. Table 5 summarizes the results of c o l l e c t i n g larvae i n di f f e r e n t bottom conditions on the Salmon River during July 26-28, 1962. Larvae (7-10 mm.) emerge from the gravel c h i e f l y during'the dark (22 and 51 larvae were collected overnight with the Surber sampler; Table 5 ) . None were collected by the same device during the four daylight periods. . Trays f i l l e d with mud and placed'in the stream i n various places collected more larvae during the night than during the day (Table 5 ) . This substantiates the results 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 recently hatched larvae from the gravel during the dark hours. The tray c o l l e c t i o n s seem to indicate that the larvae, a f t e r being swept from the gravel into a pool, bury into 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 larvae from the gravel. The current then carries the larvae downstream u n t i l the current i s reduced and the larvae then bury themselves into the bottom. 6. Bottom-type Preference  Emergent Ammocoetes A p l a s t i c tray 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 River 110 Table 5 Collection of emergent larvae from the Salmon River July, 1962. Temperature 10 to 19°C. Pool Surface Water Bottom No. of larvae i collected tray # current depth type speed 600 hr. 1400hr. 2200 hr. July: 27 28 26 27 26 27 1 .5 ft/sec : 1' Mud 2 3 1 0 0 0 2 1 » 11" Sand 8 5 0 0 0 3 3 .2 " 2' Leaves 5 1 0 2 0 2 & mud 4 .5 " 2' Rocks 21 5 0 0 0 0 & mud .5-1 " 2' Rocks 0 0, 0 0 0 0 &. mud Modified 3 ft/sec Surber 1.5' R i f f l e 51 22* 0 0 0 0 Sampler & gravel * a one year larvae was taken i n the Surber sampler. with no current flowing over the bottom materials (Fig. 4 9 ) . Lamprey larvae (8-12 mm.) were placed i n the holding trays (Fig. 49E) and the apparatus was allowed to adjust to stream temperature for a 30-minute period. Individual ammocoetes and water were taken from the holding trays with a suction tube and the contents were released into the centre of each tray. The time taken for each ammocoete to burrow into the bottom was recorded by a stop watch and additional burrowing behaviour was noted. Similar procedure was followed with a current of 0.5 f t . / s e c . The observations were made from July 26-28, 1962. Table 6 summarizes the r e s u l t s of the bottom preference by larvae that have recently hatched i n the Salmon River. The I l l F i g . 49 Experimental trough used to test the burrowing capacity of small ammocoetes. E- holding tray A- mud B- sand C- small gravel D- no cover (measurements i n cm.) Fig. 50 Experimental trough to test the bottom preference of larger ammocoetes i n the Salmon River. A- mud B- sand C- holding tray. 112 tanks were placed in'the Salmon River to t r y to duplicate natural conditions, but as the emergence, observations showed, movement of ammocoetes usually takes place i n the dark. It 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 ammo-coetes show a photokinesis. . ' A current greater, than 1 f t . / s e c . carried a l l larvae from the tank regardless of the bottom type present. The larvae buried e a s i l y into the mud when no current was present, but the sand and gravel offered resistance to the larvae. 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 to l i g h t caused the larvae to swim about continuously with 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 ating perpendicular to the bottom. At currents of 0.5 f t . / s e c . larvae maintained t h e i r position 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 effect of current drag on the body. In sand, the larva t r i e d to maintain position by forcing the head into the sand, but t h i s was impossible, so the larva was usually 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 position better than i n the sand because they could force t h e i r heads and bodies into the spaces between the. rocks and thus escape the force of the current. Later they could squeeze between the rocks. They tend to bury themselves more quickly when the current i s present because the current appears to stimulate the t a i l and thus forces the larvae to burrow completely below the surface. 113 Emergent larvae showed a d e f i n i t e preference for 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 into sand and most were unable to enter t h i s bottom type. Gravel offered shelter for the larvae from current and they could burrow slowly into t h i s bottom-type. Table 6 Bottom type preference of emergent larvae from the Salmon River. Time: s = seconds; m = minutes Bottom type Time to bury Time to bury Time i n which completely head only animal swam or was swept from tank Mud (.004cc) No current 30s, 10s, 3s 5s, 8s. Current of 5s, 10s. 5s, 15s, 10s. 0.5 f t . / s e c .  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 5m, 2m, lm, 4m, Jm. Current of 0.5 f t . / s e c . 15s, 10s, 10s. 5s, 5s. Bare bottom No current Active swimming around the tank f o r more than f i v e minutes (5 t r i a l s ) . 5s, 5s. 5s. 15s, 10s. Current of 0.5 f t . / s e c . Swept out of tank i n less 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 indicate that a thigmotaxic response by the ammocoetes may play some role i n bottom preference. Scholl (1959) reported that water ve l o c i t y over ammocoete burrows was 2.07 f t . / s e c . This appears incorrect 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 flooding. Thomas (1959) reported, "no ammocoete could burrow into an i n f i n i t e l y soft bottom i f i t could not breast the current over i t . " Ammocoetes from the Salmon River less than 40 mm. can not penetrate the softest bottom with a current over 1 f t . / s e c , while adults of L. planeri cannot maintain t h e i r position i n the stream with current above 2 f t . / s e c . Larger Ammocoetes . Ammocoetes (10-15 mm.) were introduced into the centre of the middle p a r t i t i o n of an aluminum trough with no current (Fig. 50). A current of 1 f t . / s e c was introduced into the trough and ammocoetes were introduced 4 inches from the upstream end of the tank. The time and position f o r each ammo-i coete to bury into the bottom substrate was recorded (Table 7 and F i g . 51). Sand (.005 cc.) and.mud (less than .004 cc.) were used as the bottom types for the observations. The obser-vations were recorded on September 15, 1962. With no current in-the trough the small and medium sized larvae buried into the mud quicker than the larger larvae. In the sand substrate the large larvae buried the quickest and the small larvae 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 rate 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 Sand 10-15 mm. larvae 2 5-30 mm. larvae 40-50 mm. larvae lm, 2m, 2m, lm, 2m Ids, 7s , 7s, 12s, 10s 9 s , 10s, 9s , 8s, 10s Mud 9s , 8 s , 8 s , 10s, 8s 7s, l i s , 7s, 10s, 8s l i s , 28s , 15s 20s, 14s Current I f t . / s e c . Sand 3m, lm Mud 14s, 16s, 20s, Ids, 15s 16s, 14s, 30s, 17s, 13s, 32s, 14s 46s, lm, 18s Sand Time i n which ( tank by currenl 7s, 8 s , 6 s , 7s, 7s, 8s, 7s, 6 s , 8s , 7s • animal swam or was 5s, lm, 6 s , 18s, 4 s , 8 s , 7s, 2m, 41s, 20s swept from 10s, 6 s , 10s Mud 7s, 8s, 6 s , 8s, 8s 6 s , 3s 6 s , 5s 116 sand. However, one and one half months prior to t h i s , the young of the year could not penetrate the sand. When the current was introduced only the largest 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 better i n the current. The larger 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 diff e r e n t bottom types and three sizes of ammocoetes. He found that extremely coarse-grained or extremely fine-grained substrata were seldom used by ammocoetes. The smallest ammocoetes selected the coarser-grained substrata, especially the gravel, while the larger ammocoetes selected the finer-grained substrata, especially the sand and s i l t . These are contrary observations- to those based on co l l e c t i o n s taken in the stream. Macdonald did 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 further f o r a suitable bottom. 7. Intestine Analysis of Ammocoetes Five ammocoetes d i f f e r i n g in size (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 ventral s l i t was made i n the body wall along the length of the body. The intestine was cut posterior to 1 1 7 • • MUD X . x X X X !» X X • • x • • SAND CURRENT 1 ft/sec. > X X • •••• • #••• XXXXX xxxxx F i g . 5 1 ' The position 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. larva ©Point of introduction of x - 2 5 - 3 0 mm. larva larva • - 4 0 - 5 0 mm. larva 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 int e s t i n e were scraped; from the tissue and collected on a glass 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 quantitative estimate of abundance was not determined because the organisms could not. be randomly-distr 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 less 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. Stein of the Department of Biology and Botany, University of B r i t i s h Columbia. Ammocoetes d i f f e r from most l a r v a l fishes i n that they are f i l t e r feeders and have no discrete stomach. The organisms found i n the ammocoete in 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 material 118 from decaying plant remains was prevalent i n the f a l l and winter samples. Nematode and mollusc larvae, 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 intestine of ammocoetes were smaller i n size than the smallest diatom (6, u). The l a r g -est p a r t i c l e s i n the intestines were desmids such as Cosmarium (20 u). Table 8 Intestine-analysis of ammocoetes from the Salmon River Apr. 28 June 10 Oct. 28 Dec. 16 Relative abundance (Scale 1-10) 8 10 3 1 Diatoms (Cyanophyceae) Navicula  Cymbella  Synedra  Tabellaria  Nitzchia  Hydrosera  Gomphonema . Stephanodiscus  Diatoma  Melosira  S u r i r e l l a  Cocconeis  F r u s t u l i a  Pinnularia Desmids (Ghlor Closterium  AnkistrOdesmus  Protococcus  Cosmarium  Gloeobotrys  Scenedesmus j j e # >>< # * * * * if if if if. if. if if if if if. >'f if * ophyceae) >)e if 3{c if if if Nematode and Clam larve 119 Digestion of the contents of the i n t e r i o r of diatoms occurs i n the ammocoete inte s t i n e because chloroplasts are. absent from the c e l l s i n the posterior intestine while they are present i n the anterior i n t e s t i n e . B a c t e r i a l probably play an important role 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 crystals and organic materials 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 detritus deposited i n the quiet pools. However, none of the ammocoetes obtained any food from the stream bed even though they burrowed into 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 flowing over the ammocoete beds. This food source i s also used by insects and molluscs. The use of ammocoete intestines 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. Sch r o l l (1959) found that when diatoms were available 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 detritus was consumed. He found from laboratory analysis that diatoms, marl and activated charcoal were a c t i v e l y ingested, while starch and wheat f l o u r were less a c t i v e l y ingested. Animal foods as Paramoecium, chopped tu b i c i d s , and f i s h food were taken into 120 the pharynx, .but did not appear i n the i n t e s t i n e . The Salmon River and other ammocoetes examined feed almost exclusively 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 dorsally 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 to form a conical net that s e l e c t i v e l y picks up. diatoms and to a lesser 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 flourescent dyes to show that a continuous current of water was normally drawn into ammocoete burrows. 8. The Protective Nature of the Lamprey Skin The skin of the ammocoete and adult, though lacking scales and other hard protective plates common on f i s h , i s specialized to give the animal adequate protection. The epidermis of the skin i s covered with a layer of mucus secreting e p i t h e l i a l c e l l s (Fig 52 e). The slippery nature of the skin and the wriggling 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 adults. Numerous adults have been collected with jaw" marks j many li n e s across the body and regenerated t a i l s , the conse-quences, presumably, of i n j u r i e s i n f l i c t e d by birds, c r a y f i s h , or other predators.. Stomach analysis and preliminary feeding experiments 121 were carried out to see i f f i s h would eat ammocoetes. The stomach contents'of 20 coho salmon f r y (July 27), 5 steelhead trout (July 27), 5 cutthroat trout (July 27), and 10 redside shiners (Oct. 28) from the Salmon River were care-f u l l y examined for 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 trout of West Wales to be present i n less 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 eels). C h u r c h i l l (1947) examined 300 trout 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 trout stomachs, but these f i v e were taken by rainbow trout i n early July when lampreys were abundant on the spawning gravel. The lamprey remains from the trout stomachs indicate that the adults were i n a spawned-out condition. In the post spawning adults the epidermis i s sloughed off (Applegate 1950) so the remains eaten by the trout possibly did not contain the protective substance present i n lamprey that i s s p e c i f i c to certain f i s h . Preliminary experiments to test whether salmonids would eat ammocoetes and to i d e n t i f y the location and nature of the protective substance were necessary to an understanding of the protective mechanism. Feeding experiments were set up to 122 determine whether salmonids would eat lampreys. Ammocoetes (3O-I3O mm.) were introduced, just before regular 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 size as the ammocoetes were introduced to the surface of the tank before and a f t e r the feeding with ammocoetes. The worms were immediately eaten by the f i r s t f r y on contact. The ammocoetes were taken into the mouth of the f r y but immediately spat out. In most instances an ammocoete that was rejected was immediately tasted by another f r y and again released. Each ammocoete was tasted by at least 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 tasting and releasing pro-cedure as the whole ammocoete. A worm was always eaten by the f r y at the conclusion of each t e s t . The tests were continued for a five-day period. No intact ammocoetes or ammocoete skins were eaten during the t e s t , nor were the skinned ammocoetes refused by the f r y . After the tests a l i v e ammocoete survived i n the tank a f t e r a two-day period, 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 trout a f t e r holding for 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 experimentThe same preference for skinned lampreys and a d i s l i k e for whole ammocoetes and the skin was noticed but by the fourth or f i f t h day the number of attacks was reduced to one or two at each feeding. After the completion of the tests the f r y were starved for two days and very small ammo-coetes (2O-3O mm.) were introduced. Two ammocoetes were swallowed but did not go through the regular t a s t i n g behaviour that i s common for coho f r y . Lamprey eggs were eaten rapidly by salmonids during feeding experiments. Spawning observations i n the Salmon River showed that salmon and trout 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 adults. However, lamprey eggs are usually 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 further digging. Young of the year and f i r s t year ammocoetes were eaten when fed to f r y during daylight hours i n the Salmon River. Emergent ammocoetes were eaten half the time by salmonid f r y i n a laboratory feeding experiment. Frozen brine shrimp was introduced before and after each feeding. From these obser-vations i t appears that salmonid f r y w i l l usually taste larger ammocoetes and objects before swallowing, but small ammocoetes are occasionally 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 occasionally while larger ammocoetes that contain more granular c e l l s are not eaten. Small ammocoetes remain buried i n the bottom sediments during daylight and escape predation by f i s h . They are susceptible to predation during flooding and during t h e i r d a i l y circadian movements from the bottom, but they are probably protected by the toxi c secretion from the granular c e l l s at t h i s time. 'Stomach analysis from the Salmon River during emergence indicates 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 shiners, 10 sticklebacks, and v5 spiny sculpins from the Salmon River were kept i n aerated room temperature tanks and fed l i v e ammocoetes on three occasions. The sculpins ate small ammocoetes on one occasion, but on two occasions they tasted and released larger ammocoetes. The shiners and sticklebacks never ate the ammocoetes but they did eat skinned ammocoetes on two occasions. One squawfish (Ptychocheilus oregonense)was fed l i v e ammocoetes and ammo-coete skin on ten different occasions. The ammocoetes and skin were immediately eaten on a l l occasions. P f e i f f e r (personal communication) fed ammocoetes and adults to blind cave f i s h (Anoptichthys .jordani) and adult rainbow trout. The cave f i s h ate the lampreys while the rainbow trout did not.- Perlmutter (1951) kept ammocoetes and eels i n an aquarium and recorded that the eels burrowed into the mud of the aquarium and ate some of the ammocoetes. 125 The skin of a Lampetra ammocoete was preserved i n Bouin's f i x a t i v e and stained with Azan (Fig. 52). The s i t e of the protective secretion 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 to the surface, and the d i s t a s t e f u l substance i s discharged and di s t r i b u t e d along the epithlium when the skin i s compressed or b i t t e n . Sections of ammocoete skin preserved i n Bouin and stained with P. A. S. and Toluidine blue revealed that mucus was present i n the uppermost layer 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 structure 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 tasted 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 teeth and then placed on the tongue a b i t t e r and unpleasant tast formed i n the mouth. This substantiated that the d i s t a s t e f u l substance i n the skin does not come from the mucus but i s probably forced from the skin when the skin 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 ta s t i n g i t would not respond to the protective substance i n the skin, but those f i s h that taste and hold t h e i r prey i n the mouth before swallowing would react to the skin secretion and release the lamprey. 1 2 6 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 ammo-coetes 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 1960-61 127 i n d i c a t e d a s e l e c t i o n f o r p a r t i c u l a r bottom types and p o s i t i o n s i n the stream by d i f f e r e n t s i z e d ammocoetes. In 1962 various h a b i t a t s and ammocoete beds were sampled to see i f there was any r e l a t i o n between s i z e and substrate preference ( F i g . 53)-F i g . 53 Large pool where ammocoetes are deposited, Salmon R i v e r , s t a t i o n 1. x - l a r g e r ammocoetes; o - smaller ammocoetes. Large 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 the d i s t r i b u t i o n of ammocoete beds i n r e l a t i o n to the spawning nests and current 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 during the study, while bed D was formed during the summer and beds E and F were formed during the w i n t e r months or a f t e r high flow c o n d i t i o n s . Bed F d r i e d up duri n g the summer. Ammocoete c o l l e c t i o n s from the pools of s t a t i o n 1 and 4 from the Salmon River ( F i g . 57 to 59) show th a t there 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 of ammocoetes i n the 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. Collections from the mud and s i l t near the bank (Fig. 55B and 56B) are represented by the histograms (Figures 57B, 57C, 58B, 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 (Fig. 5 5 A and 5 6 A ) are represented by the histograms i n Figures 57A, 58A, 58D, 59B, and 5 9 C These histograms show.a s i g n i f i c a n t difference from the mud bottom habitat. Second or older year classes predominate while the young of the year and f i r s t year larvae are less 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 in the sand of bed A (Fig. 56) during the winter, they were present i n September. Flooding possibly removed the smaller ammocoetes while the larger ammocoetes remained permanent residents. The ammocoete bed C (Fig. 56) composed of sand and a very t h i n transient layer of surface mud contained the same size ammocoetes as those located i n the fine mud and s i l t . The above r e s u l t s c l e a r l y show that bottom composition, larg e l y determined by current flow, influences the size 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 siz e classes between ammocoete beds shows the need for 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 ammo-coetes 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 (Churchill 1947) , and scooping L O A LU g e n a : < _ i o LL O cn UJ m z ZD L O L O L O A ©STATION 4 S A N D , L E A V E S - BOTTOM, POOL ©STATION 4 MUD, LEAVES •> BANK , POOL S A L M O N R. F E B - 2 3/62 ©STATION 3 M U D , L E A V E S - BANK ro 20 40 60 80 100 120 140 L E N G T H IN M I L L I M E T R E S FIG. 57. LENGTH - FREQUENCY DISTRIBUTION OF L. PLANERI AMMOCOETES IN DIFFERENT HABITATS OF THE SALMON RIVER ON FEBRUARY 23,1962. 20 40 60 80 DO 140 LENGTH IN MM FIG. 58. LENGTH-FREQUENCY DIAGRAMS OF LAMPETRA IN DIFFERENT HABITATS OF THE SALMON , RIVER SEPT. 9,1962. L E N G T H IN M M FIG.5a LENGTH-FREQUENCY DIAGRAMS OF LAMPETRA IN DIFFERENT HABITATS OF THE SALMON RIVER (STATION I). 13 5 from the substrate produced few larger 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 classes. 10. Relative 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 (Fig. 1 0 ) . The greatest concentration of ammocoetes wa';s found i n the sand and leaf substrate of deep pools (Fig. 60 a, f, g). Mud areas did not contain as many ammocoetes as the sand and lea 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 difference was evident. Greater numbers of ammocoetes i n the sand are probably due to the greater numbers of year classes present. Temporary winter ammocoete beds contained a s i g n i f i c a n t l y smaller con-centration 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 attained 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 ammo-coetes was proportional to bottom hardness and water v e l o c i t y . In the absence of good bottom conditions, ammocoetes were able to f i n d shelter i n almost a l l naturally-occurring bottom materials. The Salmon River ammocoetes show the greatest con-centrations i n the harder sand and leaf bottoms of pools a. DEC. 16/62 b. DEC. 16/62 c. DEC. 16/62 d. JUNE 3/62 (FLOODING) a. JUNE 3/62 (FLOODING) f. JUNE 10/62 g. SEPT. 9/62 ( 5 ) © l o © AMMOCOETE BEDS I , © FROM FIGURE 54 SAND AND LEAVES MUD ® P?773 TEMPORARY BED f~[~l MEAN NUMBER 0 •..•>..f^rn.Vjt::V:?| © © 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 NUMBER OF AMMOCOETES PER STANDARD SCOOP FIG. 60. CONCENTRATION OF AMMOCOETES FROM DIFFERENT BOTTOM HABITATS IN THE SALMON RIVER • STATION I. 137 . during the periods of reduced flow. The positions of the sand' and le a f beds (Fig. 56A) near the central current of the stream would c o l l e c t more ammocoetes than the beds at the side of the stream at low flow conditions. 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 larvae 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 larger ammocoetes can remain i n the sand beds permanently. Winter co 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 co l l e c t i o n s showed the opposite. Therefore, the ammocoetes seemed to 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 penetra-t 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 (Fig. 55 and 56) i n the deeper water (4 to 6 feet) contained the greatest concentration of ammocoetes. Thomas (1963) also found depth of l i t t l e significance because water v e l o c i t y determines s i l t deposition and position of ammocoete beds. Early workers usually recorded that ammocoetes preferred shallow water but t h i s d i s t r i b u t i o n was possibly due to s i l t deposition at the bank of streams due to a f a l l i n current v e l o c i t y rather 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 into a substrate offers some explanation of the substrate they select 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 tw i s t i n g the oral hood from side to side. These motions continue u n t i l the g i l l s l i t s are buried. The second stage involves the buried section which parts the sand ahead of the larva with the s t i f f oral hood and pulls i t s body into 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 liberated i n an aquar-ium 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 rapid vibratory movement. I t does not continue straight 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 flattened U. The dorsal 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 into 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 into the substrate. The oral hood was contracted to a point and moved from side to side to f i n d the path of least resistance. When the head and pharyngial basket were pushed forward, as f a r as possible by the swimming and wiggling motion, the o r a l hood was f l a r e d out and served as an anchor as the body was pulled up from behind. The process was repeated u n t i l the ammocoetes were covered i n the bottom and a U-shaped 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 for mud and s i l t bottoms. Applegate (1950) showed that the depth of the burrows was proportional to the larva's length with the largest larva (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 softer bottoms r e s t r i c t e d them to the surface layers i n the Salmon River. Due to the depth of burrow construction the larger ammocoetes are l i k e l y to be unaffected by flooding while the smaller specimens are l i k e l y to be carried downstream by the current, which i s what occurred i n the Salmon River (Figures 57, 59, and 60). 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 force the sharp sand grains apart and t h e i r lack of s u f f i c i e n t swimming speed to maintain a position i n current. However, sand i n t e r -spaced with leaves or containing a top layer of mud offered 140 refuge from the current. Ammocoetes from the Salmon River seem to need contact with the bottom or to have t h e i r bodies touching a substrate. Harden-Jones (1955) showed a thigmotaxic response of L. planeri ammocoetes i n the laboratory. A photokinesis response (Young 1931) also helps to keep them buried i n the mud of stream bottoms. As the animals increase i n age, t h e i r preference for bottom contact and darkness decreases. Leach (1940) found that transforming brook lamprey gradually l o s t t h e i r preference for 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 into the mud. The bottom of the tank was marked off into 16 equal parts by a grid f i t t e d over the top of the tank so that the exact position 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 to December 31. One of the sections was randomly chosen as a control square and contained no lampreys. This square was partitioned off with nylon cloth so that wdrm and insect burrows could be differentiated'from those of ammocoetes. Over a 24-hour period never more than 20% of the burrows remained unchanged. A l l burrows had shifted position over a 48-hour period. New burrows were formed during the day and night. No ammocoetes were seen outside t h e i r burrows at 1 4 1 any time. Thomas ( 1 9 6 3 ) observed s i m i l a r results for the . sea lamprey, but he found no evidence of circadian rhythm of burrow construction or leaving the burrow during the dark. He took photographs of the ammocoete burrow mouths but found no ind i v i d u a l s v i s i b l e during the darkness. He found a circadian 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 ( 1 9 6 3) collected ammocoetes i n weirs at dawn and dusk and showed that migration occurs almost exclu-s i v e l y downstream and at night. He correlated t h i s migration d i r e c t l y with water temperature and water flow. Migration of ammocoetes would account for the s h i f t of age composition and concentration within the ammocoete beds of the Salmon River. A spawning migration of adult lamprey from the region below station 1 to above station 1 i s suspected because the ammo-coetes moving to new burrows are displaced downstream, but they must return to gravel areas to spawn i n the spring. 1 3 . Growth of Ammocoetes The lamprey.of B r i t i s h Columbia and Washington are characterized 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 classes from length-frequency data very d i f f i c u l t . The modes of the fast growing individuals 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 distinguished i n most c o l l e c t i o n s (Figures 6 l and 6 2 ) . The yearly growth f o r the f i r s t two year classes was plotted from the position of the modes at various times throughout the year and two curves were f i t t e d by eye (Fig. 6 3 ) . These growth curves reveal a period of slowing down or cessation of growth during the winter months. This, was also suspected by Schultz (1930) for L. planeri i n Washington State. The young of the year i n the Salmon River grow rapidly from June to : November while the f i r s t year larvae grow most rapidly from A p r i l to August. Intestine analysis of larger 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 rather scarce i n the la 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 positions of modes i n the Salmon River (Fig. 62) with that of other r i v e r systems (Fig. 6 l ) reveals a great s i m i l a r i t y of modes for the f i r s t year classes. This suggests that most Lower Fraser Valley streams and Vancouver Island streams produce ammocoetes that have the same growth rates. The preference for 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 larger ammocoetes occupied the variable 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 (Fig. 62) show a great v a r i a b i l i t y i n the year class 143 TSOLUM RIVER AUG. 29 1961 VARIABLE BOTTOM 20 30 40 50 LENGTH IN MM FIG. 61 LENGTH-FREQUENCY DISTRIBUTION OF AMMOCOETES FROM CERTAIN STREAMS IN BRITISH COLUMBIA . 144 A 62 Length-frequency d i s t r i b u t i o n of ammocoetes from the Salmon River , 1960-1963. 144 B A 1962 • 1961 O I960 I — , 1————i 1 r— 1 1 » ~ 1 • " 1 ~~* JUNE JULY AUG SEPT OCT NOV DEC JAN F E B MAR. APR. MAY FIG. 63.GROWTH OF AMMOCOETES (L. planeri ) IN THE SALMON RIVER DURING THE YEAR I960- 62 (curve f i t t ed by eye ) 146 as collected 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 habitats. Sampling a v a r i e t y of habitats produced a variety of year classes and represented the population, but samples of a r e s t r i c t e d area usually revealed only one or two year classes. 14. £. tridentatus Ammocoetes from the Thompson and Nicola  River Collections of E. tridentatus larvae were taken from t h i s r i v e r system on three occasions f o r comparison with the mixed population (Lampetra and Entosphenus) from the Salmon River. The August 19, 1961 c o l l e c t i o n was taken from three •different habitats and locations on the r i v e r system to compare with s i m i l a r habitats i n the Salmon River. In the Nicola and Thompson Rivers the stream bed i s characterized by r i f f l e and pool areas. The r i f f l e areas contain large boulders and larger gravel size than that present i n the Salmon River. The pool areas of the Nicola 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 larger for the Thompson and Nicola 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 larvae seem to exhibit s i m i l a r preference for bottom type as the Salmon River population. The smaller larvae (Camford Station) were collected i n a predominantly mud bottom while the larger ammocoetes were collected i n the sand and leaves of pools (Dot station) of the Nicola 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 OF ENTOSPHENUS L A R V A E , AUG. 19/61 148 on the Thompson River. Figure 6 4 indicates an increase i n the number of smaller larvae as the coll e c t i o n s were taken farther up the Nicola River. This could indicate a spawning above Merritt and a migration downstream by the larvae. However, l a t e r c o l l e c t i o n s indicate large ammocoetes i n the upper r i v e r as w e l l . Thus habit selection by the ammocoetes and sampling v a r i a t i o n , as well as some downstream migration would' be possible explanations for t h i s d i s t r i b u t i o n . The length-frequency histograms (Fig. 65) show the data collected and means for each age class can be followed, throughout the c o l -l e c t i o n s . L. planeri and E. tridentatus exhibit s i m i l a r l a r v a l requirements and general stream behaviour. E. tridentatus possess a fa s t e r growth rate and a possible shorter l a r v a l period than L. plan e r i . The intestines of 10 ammocoetes from 1 the Nicola 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 in t e s t i n e s . The increased diatom intake by the ammocoetes may account for the faster growth rate of Entosphenus i n the Thompson and Nicola Rivers than the mixed population (predominantly Lampetra) of the Salmon River. 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 analysis devised by Harding (1949) and extended by Cassie (1954). Two of the largest coll e c t i o n s of L. planeri 149 THOMPSON RIVER F E B . 24/62 10-NICOLA RIVER AUG. 2 / 8 2 LU < > or <Uo-_j QC 111 20 CD Z 13 10 2 10 20 30 LENGTH NICOLA and THOMPSON RIVER AUG. 19/6 1 40 50 60 70 80 90 100 110 120 IN MILLIMETRES FIG.65. L E N G T H - F R E Q U E N C Y OF ENTOSPHENUS LARVAE FROM THE NICOLA and THOMPSON R. 150 (10 percent E. tridentatus) from the Salmon River (Fig. 66 and 67) containing the greatest number of year classes were selected for the p r o b a b i l i t y paper analysis. The two large c o l l e c t i o n s of E. tridentatus from the Nicola and Thompson Rivers (Fig. 68 and 69) were used to separate the year classes. A summary of the p r o b a b i l i t y paper analysis 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 deviation f o r each age class. The two c o l l e c t i o n s of each species when plotted offered a check f o r picking the correct i n f l e c t i o n points. The growth curve for each species was drawn by eye from the mean of each age class' (Fig. 70 and 71) and the 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 as two minor nodes could be accepted instead of a single age 3 node. I f the age 3 minor nodes were plotted as i n F i g . 71 then the growth curve would not correspond to the curve of the other sample (Fig. 68). The major age three node places the curve i n agreement with the other sample of E. tridentatus. The i n f l e c t i o n points for both L. planeri samples showed good agreement when the growth curve was f i t t e d . , A comparison of the growth of L. planeri and E . tridentatus shows both curves to be very s i m i l a r . A s l i g h t l y more rapid rate of growth occurred i n E. tridentatus ammocoetes. This could be due to differences i n n u t r i t i o n . E. tridentatus appears to decrease growth i n the older larvae stages as indicated by the growth curve, but t h i s i s possibly due to STANDARD PERCENT DEVIATION 84.13 CONFIDENCE LIMITS,P*05. 80 90 99 FIG. 67. 10 20 30 40 50 60 70 CUMULATIVE FREQUENCY (% ) SEPARATION OF POLYMODAL FREQUENCY DISTRIBUTIONS OF L. PLANERI AMMOCOETES USING PROBABILITY PAPER (SALMON RIVER, F E B . 2 3 , 1962 ) STANDARD PERCENT DEVIATION CONFIDENCE LIMITS.P=05. 80 90 99 FIG. 67. 10 20 30 40 50 60 70 CUMULATIVE FREQUENCY ( V . ) SEPARATION OF POLYMODAL FREQUENCY DISTRIBUTIONS OF L. PLANERI AMMOCOETES USING PROBABILITY PAPER (SALMON RIVER, F E B . 2 3 , 1962 ) FIG. 68. SEPARATION OF POLYMODAL FREQUENCY DISTRIBUTIONS OF E . TRIDENTATUS AMMOCOETES USfNG PROBABILITY PAPER ( THOMPSON AND NICOLA RIVER , AUG. 19 , 1961 ) 15 10 5 ' 1 ' 1 1 • —I • i l 1 | | I I L. 10 20 30 40 50 60 70 80 90 99 CUMULATIVE FREQUENCY ( '/» ) FIG. 69. SEPARATION OF POLYMODAL FREQUENCY DISTRIBUTIONS OF E. TRIDENTATUS AMMOCOETES USING PROBABILITY PAPER ( NICOLA RIVER, AUG. 2 , 1962 ) 155 Table 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 . L. p l a n e r i Date Age Percent Mean Standard D e v i a t i o n Sept. 9/62 0 39 17.5 2 .4 1 20 36 4.17 2 17 47.5 3-76 3 14 58 3.6 4 6 72.5 4.14 - 5 5 95.5 9.92 Feb. 23/62 0 32 22 2.96 1 40 40 5.16 2 9 53 5.88 3 5.6 66.5 5.54 4 4« 4 84 8.6 5 9 110.5 9.55 E. t r i d e n t a t u s  Date Aug. 2/62 Aug. 19/61 0 3 9.8 . 1.29 1 16 35.5 2.31 2 16 . 44.5 5.5 3a 18 55.5 3.6 3 35 60 5.4 3b 17 65 2.85 4 19 76.5 5.27 5 11 91 6.3 0 36.6 17.5 2.37 1 20.4 39 5.5 2 14 52.5 5.1 3 13 67.5 5.1 4 10 78.5 3.1 5 6 97 10.1 156 FIG.70.GROWTH CURVE OF L A M P E T R A P L A N E R I FROM THE SALMON RIVER 157 i i i i i i I 2 3 4 5 6 AGE IN Y E A R S . FIG. 71. GROWTH 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 THOMPSON RIVER 158 FIG.72. GROWTH CURVES OF BRITISH COLUMBIA L A M P R E Y S (NICOLA AND SALMON RIVER ) 159 d i f f i c u l t i e s i n aging the older la rvae . The 10 percent of E. t r identa tus mixed with the L . p laner i population of the Salmon River would seem to have l i t t l e or no effect on the analysis 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 laner i appears to be 6 years or more and that of E. t r identatus i s 7 years or more. No allowance was made for possible reduction i n length before transformation, for premature i n d i v i d u a l s , or for the presence of a rest per iod. 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 laner i to be three years. Zanandrea (1951 and 1954) and MacDonald (1959( calculated 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 laner i i n England at about f ive and one-half years from large samples co l l ec ted throughout each year from 1940 to I960 i n one r i v e r system. He determined that ammocoetes grow more r ap id ly 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 length . He estimated that the annual mor ta l i ty rate of ammocoetes was . f a i r l y uniform throughout the l a r v a l per iod. The growth curve of B r i t i s h Columbia lampreys agrees with the shape of Hard is ty ' s lamprey curves but both do not represent the actual growth because of lack of knowledge of the biology of the l a s t few years of l a r v a l l i f e . The percentage of each year class 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 for each species (Table 9)• The means of the year classes show a very good f i t f o r the growth curve (Fig. 70 and 71). The standard deviation f o r the f i r s t " to t h i r d age classes show, remarkable consistency but variations increased with the larger age classes. This i s possibly due to a rest period, sexual differences i n growth, or i n d i v i d u a l differences i n growth. The growth curves of the ammocoetes f o r the two species of lampreys (Fig. 72) are representive of ammocoete growth up to ages 3 or 4, but then the curve becomes inconsis-tent with the biology of- the larger larvae. The accumulated variables of i n d i v i d u a l growth, length differences with sex, possible reduction i n length before transformation and the presence of a rest period a l l tend to make length frequency analysis inadequate f or the larger sized larvae. Growing marked ammocoetes i n a stream environment from age two or three would be desirable. I f l o c a l ammocoetes possess a rest period, then the growth curve up to transformation would take on the shape of the von Bertalanffy growth curve f o r length. k ( t - t ) L.t = Loc( 1-e 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 calculated for the B r i t i s h Columbia lamprey growth ( as used by Thomas 1963) but t h i s would only be an approximation and crude representation of actual ammocoete growth. Hardisty (1961), Okkelberg (1922), and Hubbs (1924) presented growth curves for 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 ri 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 rapidly 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 spring. Complications of biology just before transformation prevent a more detailed mathematical representation of the growth curves. 16. Transformation or Metamorphosis of Ammocoetes  L . planeri A few transforming individuals were collected during September and October i n the Salmon River and during August i n the Tsolum River. Ammocoetes larger than 90 mm., transforming ammocoetes, and adults are compared i n the length-frequency diagrams i n F i g . 72. A reduction of ammocoete size at trans-formation could conceivably take place i n the Salmon River population because the largest ammocoetes are larger than the transforming ammocoetes and there i s l i t t l e difference i n the range i n size between the three groups of Lampetra. In the 162 Tsolum River c o l l e c t i o n one transforming la rva was la rger 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 ize.from t h i s observation. Most workers who have examined transforming larvae have reported that ammocoetes decreased in 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 he i r length by 10 percent at'metamorphosis. He maintains that ammocoetes may spend an ent i re year i n the f u l l grown condi t ion or "rest period" before onset of the transformation per iod. He found that one-third of the ammo-coetes wi th in the l i m i t s of ' t ransformation s ize transform wi th in a year. Gage (1927) suspected a rest period existed i n the sea lamprey. A rest period could conceivably exis 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 ize range from the largest ammocoete to the adul t s . Thus growth could stop, or the ammocoetes could | decrease i n length, before transformation. Leach (1940) divided the transformation period into three sub-d iv i s ions : a rest period which precedes metamorphosis and extends for one year, the l a t t e r part being a non-feeding stage; an ear ly 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 for Lampetra. Leach reported that the. ' intest ine of the early ammocoete stage was t> H Z 5 MOC vi U o I -m rn - H z m o CO -1 I > 1 z n a X m > p o c c m x— z -\ o CO •< O D T1 > a t— X > > Z 2 X CO m TRA OF H > z > o z cn m T l z o -» a o Z (A TJ z X o m z c r -> CA 31 < > m N U M B E R O F L A M P R E Y N U M B E R O F L A M P R E Y m - i o Z " V ) o U l 0 ) V I > H O X c > w -n o x Z z o > X < > m *> Z Z o o o m —» m CO X > • z CO m m z o H X o •n m z -t o CO X X m z c (A fa) - 1 — f 3 25 > o x o I > 55 \< W X O VO 164 empty and reduced i n size from that of the largest ammocoetes. This also occurred i n the same stage for the Salmon River brook lamprey. ' Changes i n shape and form that occur during the trans-formation from ammocoete to adult can be seen i n F i g . 73 and 74. The transformation from ammocoete to the.early transforma-t i o n stage (Fig. 73-B) apparently occurs rapidly within a month or less (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 for many months and gradually f i l l s with teeth and increases i n size (Leach 1940). The g i l l openings become rounded and the brachial basket enlarges. The ventral groove of the endostyle disappears in' the older forms (Fig. 7S-A). The naso-pituitary i s enlarged and specialized i n the transforming and adult forms (Kleerekoper and van Erkel I960). Leach (1940) described detailed changes i n I . fossor by observing metamorphosis i n the laboratory. He observed that the in t e s t i n e i n large ammocoetes was a few millimetres i n diameter and f u l l of food, but i n transforming larvae the i n -testine was empty and reduced i n diameter to less than one millimetre. The intestines of B r i t i s h Columbia transforming larvae, showed the same reduction i n size and i t also 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, leaf and mud sediment beds during the.late summer or early f a l l . A l l specimens of 165 F i g . 74 A comparison of the size and shape of transforming larva of L. planeri. A- ammocoete. B- large transforming ammocoete (Tsolum River) C- small transforming larva. D- female adult (Salmon River). E- male adult (Salmon River). Fig 75 A comparison of the head of L . p l a n e r i . 1- Lat e r a l view. 2- Ventral view. 3- Dorsal view. A- Ammocoete. B- Transforming adult. C- Adult (length- 140 mm.). 166 transforming larvae were taken from deep water (> 3 f e e t ) . Transforming larvae were never collected i n winter from the Salmon River. 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 laboratory and found they appeared to be hiding with the pharynx extended above the burrow and retracted into the burrow when danger threatened. Ammocoetes w i l l reburrow under s i m i l a r circumstances. Gage (1928) reported that transforming lamprey remain i n the mud and sand l i k e the larvae, but they are often found i n deeper water. Entosphenus Transforming larvae were collected i n the Big Qualicum River i n August i n d i c a t i n g that transformation would start i n July. 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 Nicola and Thompson Rivers i n December and March. This indicates a rapid transformation or a f a l l transformation. Transforming Entosphenus larvae are smaller i n size than Lampetra larvae . although the Nicola : River larvae should, be larger as they were collected i n March. Collections suggest that transformation' takes one year to complete as transformed larvae or early adult stages were collected on the i r r i g a t i o n screens of the Nicola River i n August (C.C. Lindsey, personal communication). The presence of a rest period was not determined but the absence of large ammocoetes i n the N i C 0 l a River could mean reduced 167 growth or absence of the rest period. The same changes i n shape occur i n transforming Entosphenus as those i n Lampetra. D. Community Relationship 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 residents i n the Salmon River. 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 fishes of the stream so no competition f o r a food source exists between fishes and ammo-coetes. However, i n the Salmon River, the microscopic algae and detritus i s used by ammocoetes, fresh water clams (Anodonta), c r a y f i s h (Pacifastacus), ephemeroptera nymphs and oligochaetes (Tubifex). The ammocoetes appear to be highly adaptive and successful members of the bottom community of the stream. -The predation upon lamprey ammocoetes by f i s h , am-phibians, bi r d s , and mammals i s doubtful because of the foss-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 skin. The greatest mortality i n ammocoetes occurs just a f t e r hatching when the yolk sac i s used up p r i o r to feeding. Piavis (I960) found the highest mortality rate i n the land-locked sea lamprey occurred from hatching to the pre-larvae stage. Lennon (1955) reported a large 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 laboratory. How-ever, i n the stream the adhesive eggs are securely buried i n the nest and ammocoetes emerge at night, thus escaping 168 predation, as i s indicated by a lack of ammocoete remains i n the f r y stomachs. Potential lamprey predators such as the blue heron (Ardea herodias) . racoon (Procyon lotor) , and the mink (Mustela  vison) are present i n the Salmon River area, but due to the abundance of salmon and trout f r y throughout the year, i t i s unlik e l y that they would burrow into the mud fo r ammocoetes. On numerous occasions observations were made of predation by Ephemeroptera nymphs and small crayfish upon ammo-coetes 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 to that made by a bird's b i l l have been seen i n Lampetra and Entosphenus i n the Salmon River. Hardisty (1961) found, " a r e l a t i v e uniform rate of mortality which the estimate's show i s hardly surprising i n view of the sheltered and stable habitat of the ammocoetes, where except during metamorphosis, there i s l i t t l e tendency f o r seg-regation of the animals with respect to t h e i r age". He assumes that there i s a very heavy mortality during the f i r s t few months of l a r v a l l i f e , e specially i n the period when the newly emergent ammocoetes are d r i f t i n g downstream to the ammo-coete beds and again during the vulnerable phase of metamor-phosis. M o r t a l i t y a f t e r hatching was observed i n the Salmon Hiver lamprey, but mortality of emergent ammocoetes and trans-forming larvae was not observed. Entosphenus The community relationships 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 mortality 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 ra r e l y equalled i n history and can be attributed i n part to the absence of predators or b i o t i c control i n the fresh water en-vironment. The endemic fresh water forms, "offer l i t t l e or no control by competition, disease, parasitism, or predation" (McLain 1951). The discovery of the protective substance i n the skin of lamprey which protects them from many species of predacious fresh water f i s h , may account for the low mortality rate. However,' there are few records of lampreys i n stomach analysis of marine fishes.' Adult lampreys were recorded i n the stomach of a sperm whale off the Queen Charlotte Islands and from the mouth of a fur seal off Cape F l a t t e r y ( P i i e 1953) which indicate that lampreys go many miles into the open sea and would be suceptible to great predation. The effect of Entosphenus parasitism on the f i s h of the sea and certain Vancouver Island lakes i s pronounced but the extent to which f i s h are k i l l e d or affected by the parasite 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 substantial i n many areas of B r i t i s h Columbia. Their effect on other community members was d i f f i c u l t to determine. Limited observations from the Salmon River suggest that ammocoetes occupy a ni t c h and exploit 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 coastal 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 soft 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 include 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 certain sections of stream bottom. The d i s t r i b u t i o n of lampreys within the coastal streams i s incompletely known but extensive c o l l e c t i n g may f i n d them occupying most streams. A l l streams examined on Vancouver Island revealed lamprey ammocoetes as residents. The size of E. tridentatus populations and t h e i r d i s t r i b u t i o n along the coast should reveal 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. planeri i n B r i t i s h Columbia., that have d i f f e r e n t tooth patterns, myotome counts, and growth rates-. A key to separate large ammocoetes of L. planeri from those of E. tridentatus i s presented, but a key to ammocoetes of smaller size classes i s needed. Separation of l a r v a l ammocoetes by the size of gonads using the method used by Hardisty (i960) seems to offer p o s s i b i l i t i e s . The 171 position of L. ayresi and i t s l i f e h istory i s unknown except for a few p a r a s i t i c adults that have been collected on f i s h i n the S t r a i t of Georgia. The spawning behaviour of lampreys offers a r i c h and unexplored f i e l d f o r the comparative ethologist. The primitive phylogenetic position offers i n t e r e s t i n g s t a r t i n g points to trace origins and evolutionary develop-ment of spawning behaviour found i n f i s h . Adult lampreys w i l l spawn re a d i l y i n s t i l l or running water i n an aquarium containing gravel, yet feeding and conditioning requirements present i n f i s h are apparently almost non-existent. The change i n spawning behaviour with temperature changes presents an int e r e s t i n g behaviour pattern. The effect of temperature on spawning behaviour of L. planeri 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 to be predominantly female at the st a r t of the season, but l a t e r i n the season males predominated ( also recorded by Surface, 1897). A review of the data presented by Applegate (1950) on the sex-ratio i n Carp Creek reveals that there may be some correla t i o n between sex-ratio and temperature as wel l as between sex-ratio and abundance and year class s i z e . In his observations the lowest sex-ratio 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 early A p r i l and May and the sex-ratio was the highest i n t h i s year. 172 In 1947 his data showed a 5:1 r a t i o throughout the season with a 2 :1 r a t i o i n early May and a 3 ; 1 r a t i o i n June. From the Salmon River observations the low temperatures may be responsible for causing the males to bury i n the gravel or becoming less active; hence they w i l l not be collected as read i l y as the females. Collections of adult lampreys for sex-ratio analysis should be made at regular i n t e r v a l s throughout the season to overcome the sampling error associated with behaviour differences caused by temperature. Correction for a longer l i f e of males during the spawning season should also be considered i n sex-r a t i o determinations. The L. planeri males of the Salmon River were found to l i v e considerably longer than the females at a l l temperatures tested. Zanandrea (1^61) found that the sexrratio 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 to the greater s u r v i v a l rate of the male. However, from the Salmon River data, low stream temperature as well as longer l i f e of males could be suspected. Hardisty (1954) suggested that the difference i n sex-ratio 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 reveal basic s i m i l a r i t i e s that could be used to trace the evolution of dif f e r e n t species of lampreys. The, early- ammocoete l i f e may reveal taxonomic c h a r a c t e r i s t i c s tha^ could be used to separate diff e r e n t species. The range of-temperature tolerance and the effect of temperature on 173 development should prove helpful i n understanding the b i o l o g i c a l requirements and tolerance ranges that the animals can with-stand (similar to Piavis 1955). The mortality during hatching i s very important because the stage when the yolk-sac i s exhausted but before the juvenile 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 in early l i f e of. most fishes ( Beverton and Holt 1956). Sampling methods and size are extremely important i n presenting an unbiased description 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 variety of c o l l e c t i n g methods that sample a l l stream habitats would most l i k e l y be representative of the population. Most workers have used either e l e c t r i c shockers or scooped the sediments onto the shore. The f i r s t method selects f o r the larger specimens while the second does not produce adequate samples of the larger ammocoetes. Both of these methods plus downstream traps would produce the best sampling. Different sections of the r i v e r , or even sections of the same pool, produce diff e r e n t size classes, thus the entire length of large sections of the r i v e r and . each of the bottom types should be sampled to account for d r i f t i n g or migrating fractions of the population. The. biology of ammocoetes i s very d i f f i c u l t to interpret 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 existing methods. However. 174 organic dyes have recently proven successful i n marking lampreys (Wigley 1952). The protective nature of the mech-anism by which emergent ammocoetes leave the gravel at night and s e t t l e downstream i n the pool areas i s poorly understood. Harden-Jones (1955) indicated from laboratory experiments that ammocoetes are photokinetic but his data also indicated that ammocoetes are s l i g h t l y thigmotaxic. This could explain the possible need by ammocoetes to have mud i n contact with the body surface. A thigmotaxic response i n conjunction with diurnal or circadian rhythms could account for downstream mi-gration and d i s t r i b u t i o n i n the stream. Different year classes are collected in. d i f f e r e n t habitats or bottom types, but why each size 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. Detailed analysis of the f i l t e r feeding mechanism of ammocoetes requires further study. The endostyle net can apparently pick out diatoms and desmids from mud, yet proto-zoans and organic matter such as starch are rejected. The rate of food passage through the gut and the actual u t i l i z a t i o n of the material i s worthy of consideration. Ammocoetes seem to be able to withstand long periods without food as i s indicated 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 re-duction of the gut at transformation indicates a period of l i t t l e or no feeding i n the la t e ammocoete stage. The rest period described by Leach (1940) may also be associated with 175 a cessation of feeding. The adults of both species studied do not feed from the early f a l l u n t i l spawning, but the f a t ac-cumulated by the ammocoetes of L . planeri, and from a p a r a s i t i c early adult l i f e of E. tridentatus i s used to keep the animal a l i v e . 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 distorted and inaccurate inform-ation i n view of recent information as to the presence of a rest period. Shortening i n length at transformation, the presence of a rest period, d i f f e r e n t i a l growth rates between the sexes, and differences i n i n d i v i d u a l growth that originate from a long spawning period make the analysis 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 length-fre-quency analysis produces (usually) an age considerably smaller than the actual age of the animal. Strauffer (1962 ) prevented recruitment i n the sea lamprey and allowed the population to go to extinction to show that l a r v a l l i f e i s longer than previously calculated. Wigley (1959) found a better estimation of age up to transformation can be obtained from weight-frequency d i s t r i b u t i o n s . The determination of age structure and growth i n lamprey populations by the p r o b a b i l i t y paper method (Harding (1954) f o r analysis of length-frequency d i s t r i b u t i o n s 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, certain 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 class 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 also 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 well 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 within each mode are usually assumed, but di 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 to apply to the lamprey population analysed when a von Bertalanffy growth curve i s assumed. These are: 1. That there i s no difference between year-classes i n respect to 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 necessarily a random sample of several age-classes simultaneously). 3. That there be no correlation between size of a f i s h within an age-class> and the mortality rate to which i t i s subject. It i s worth noting that an analysis which gives.a s a t i s f a c t o r y f i t may not necessarily be the most complete picture of the facts which may r e a l l y conform to one of the many complex solutions. There may be smaller groups within 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 solution 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 (Harding 1949). Transformation of lamprey ammocoetes i s poorly understood, but the mechanism that i n i t i a t e s the change has been the subject of s p e c u l a t i o n by many workers. Trans-formation was thought to be as s o c i a t e d w i t h the formation of the t h y r o i d gland or unique s e m i - f o l l i c l e s w i t h i n the endo-s t y l a r organs (Leach 1939)• The s e m i - f o l l i c l e s are thought to represent the transformation t i s s u e and accounts 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 of the animal r a t h e r than growth i n l e n g t h . 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 f a i l e d t o produce metamorphosis. Horton (1934) i n i t i a t e d anuran metamorphosis by i n j e c t i n g t h y r o i d from the adult lamprey. The endostyle of the ammocoete contained no i o d i n e (Knowles 1941)• Knowles fed tadpoles ammocoete endostyles but no metamorphosis occurred. He a l s o t r i e d to 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 Atz (1957) a n t i c i p a t e t h a t hypophysisectomy would prevent the metamorphosis of ammocoetes. In tadpoles a short period of s t a r v a t i o n j u s t before metamorphosis i s s a i d t o a c c e l e r a t e the transformation i n t o the a d u l t form (Barfuth 1887, quoted by Thompson 1942). H a r d i s t y (1961) suggests t h a t a d e c l i n e i n abundance of phyto-plankton i n l a t e summer might be r e s p o n s i b l e f o r the seasonal onset of metamorphosis i n lampreys. However, the lampreys of Leach (1940) and the lampreys stu 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 start 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 intestines were f u l l of phyto-plankton. This suggests,that transformation i s associated with a cessation of.feeding by the ammocoetes. Parasitism i n the lake environment and In the sea i s poorly understood for B r i t i s h Columbia lampreys. Parasitism has been recorded 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 adults or observations of scars. Larger lampreys have been recorded attached to large cutthroat trout 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 directed to t h i s area u n t i l the l a s t few years and i n f o r -mation, i s s t i l l inconclusive. The extremely small size of scars on the E l s i e Lake trout i s i n d i c a t i v e of a reduction i n size that i s associated with landlocked races. The effect of p a r a s i t i c lampreys on marine f i s h has produced few records of incidence except for troll-caught salmon (Milne I960, personal communication). I t would seem reasonable 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 attaching to slower moving, bottom dwelling f i s h . I f lampreys are preying on other f i s h besides salmon, the incidence may not be recorded or may be less common. No evidence of lamprey k i l l i n g f i s h has been presented i n B r i t i s h Columbia. 179 The homing i n s t i n c t of lampreys offers a unique f i e l d for study, especially since Wigley (1952) has found that organic dyes can be used to mark lamprey successfully. The long migrations of E. tridentatus 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 in the sea may be a threat to 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 appraisal 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-trifludr-methyl - 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 affect other f i s h ( Applegate et a l . 1957). This chemical could be used to reduce the number of E.  tridentatus ammocoetes i n the streams and lakes where popu-l a t i o n s and parasitism warrant i t . Lake lampreys (Kennedy 1958) have complicated the control problem i n the Great Lakes by spawning i n the lakes and thus making control impossible. The evolution or speciation of non-parasitic 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 non-parasitic l i f e i s associated with a supposed shortening of the. l i f e cycle, removal of the migratory phase, shortening of the length of the body, and a reduction i n dentition and fecundity. "The degenerate or brook lampreys appear to have been independently derived from d i f f e r e n t p a r a s i t i c species", •" 180' according to Hubbs (1924)- Zanandrea (I96l) discussed, speciation. of lampreys and arranged them i n pairs where non-p 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 possible paired group of lampreys i n B r i t i s h Columbia i s ' t h a t of L. planeri (non-parasitic) and L. ayresi ( p a r a s i t i c , e a r l i e r called 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 pair indicates the recent evolutionary divergence of the two species (Hardisty 1963). However, t h i s pair could be. North American extensions of European L. planeri 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 parent form. No paired form of E. tridentatus occurs at present but a small race that i s shorter i n length may be evolving. 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 si m i l a r to a landlocked smaller form that i s suspected i n E l s i e and Cowichan Lakes. Paired lampreys are usually 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 biology i s very different (Zanandrea 1 9 6 l ) . One of the paired species does not feed after metamorphosis while the other (parasitic) form preys on f i s h . 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 (large egg number). The formation of a landlocked race from a p a r a s i t i c lamprey seems to indicate the f i r s t step i n divergence to a • ; 181 non-parasitic existence. Landlocked sea lampreys are charac-teriz e d by a,reduction i n size and fecundity, but a reduced mortality usually 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 size 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 -esting i n these instances to observe the dir e c t i o n of evolution of the landlocked lampreys af t e r the f i s h population i s removed or reduced. Laboratory rearing of the landlocked form and removal of the feeding stage or subjecting them to s a l i n i t y changes could^have i n t e r e s t i n g implications to lamprey l i f e cycles. The interactions between lampreys and other community members have never been investigated. Ammocoetes seem to occupy a habitat and exploit a food supply (algae) that i s unused i n most stream environments. The protective nature of the skin, reduced predation, f o s s o r i a l habits, and nocturnal behaviour enable ammocoetes to have a low mortality rate. Speculation as to why lampreys dominate the fresh water envir-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 in t e r e s t i n g ecological 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 just increased numbers of predators may cause the difference. The behaviour of lamprey prey i n the lakes may be quite d i f f e r e n t from that of di 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 -val advantage despite the increased egg number of the sea lamprey. Lampreys offer a fascinating and re a d i l y available source of interest that' warrants further 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 introductory work i n B r i t i s h Columbia. 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 essential. 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 preferred but not essential. B. Prespawning 1. Gather near the r i f f l e areas. 2. Active movement and searching on the r i f f l e area (nocturnal) . 3 . Play with stones and in d i v i d u a l mock spawning actions. 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 action. 2. Combined rock l i f t i n g and digging. 3 . Digging action. D. Spawning Sequence 1. Seeking out partner and courting 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 act, head grasping and entwining of the t a i l about the female, vibrations and release of sex products into the gravel. 5. Eggs are covered and attached to sand grains i n the 184 bottom of the nest. 6. Short rest 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 with high i n t e n s i t y spawning. E. Post Spawning 1. A l l animals die shortly after spawning - temperature controls the period of l i f e . SUMMARY OF THE LIFE CYCLES A. Lampetra planeri ( as outlined 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 rest period of one year with reduced growth and reduction i n size before transformation (speculation only). 5. Early transformation period from August to November. Feeding stops and great changes i n body form occur. 6. Immature adult period from November to March. Trans-formation i s completed and the sex organs enlarge. 185 7. Active adult period and spawning- from A p r i l to July. 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 s i x years. 1 Entosphenus tridentatus l.-5« s i m i l a r to Lampetra 6. 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. Active parasitism on f i s h i n the sea- twelve to twenty months. 8. Migration upstream - July to September. 9. Immature adult stage- October to March. No feeding, hiding under stones i n the stream. 10. Active adult or spawning period - A p r i l to July. 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 cycle (egg to adult) i s more than seven years. 186 CONCLUSIONS 1. Eggs of L, planeri started hatching i n 15 days at 15°C. o and i n 13 days at 17 C.. E. tridantatus eggs started hatching four days l a t e r than L. planeri at the same temperature (15°C.). 2. Two to three week old larvae emerge from the gravel at night, are carried downstream by the current to the soft 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 larger ammocoetes can penetrate most bottoms but they prefer a sand, leaf and s i l t bottom. 5. The greatest concentration of ammocoetes were found i n the sand, leaf 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 mud during each day. 7. Large ammocoetes of L. planeri can be separated from those of E. tridentatus by myotome counts and examination of pigment areas. 8. B r i t i s h Columbia L. planeri i s quite d i f f e r e n t taxon-omically from the European form of the same species. 9. The Salmon River adult L. planeri represents a dwarf race of the brook lamprey. 10. Two d i s t i n c t size groups of E. tridentatus are present i n the, Salmon River. < 11. Incidence of E. tridentatus parasitism occurs i n E l s i e and Cowichan Lakes on Vancouver Island and i n the ^sea. 12. Greatest incidence of parasitism by E. tridentatus i s confined to the early spring i n the lakes and to the summer i n the sea. • 13. More female L. planeri were collected i n the lower Salmon River than i n the upper r i v e r . 14. Female L. planeri are s i g n i f i c a n t l y larger than males i n the Salmon River. j 15. The egg diameter of both species i s s i m i l a r . The range of egg number for L. planeri i s 1,100 - 3,700 and that of E. tridentatus i s 10,000 - 106,100. i o 16. Adult L. planeri spawn at temperatures above 10 C i n the stream but at lower temperatures the females remain active yet the males bury into the gravel. 17. The spawning behaviour i s very s i m i l a r between the two species examined and that recorded for other species. 18. A long spawning period from A p r i l to July occurs f o r L. planeri i n the Salmon River, low temperature increases the period. ^ 19. Spawning adult L. planeri prefer r i f f l e areas i n the stream that are shaded and contain a current greater than 1 foot per second. 20. No'intromission occurs during the spawning act i n both species. 21. Temperature has a marked effect on the i n i t i a t i o n of nest construction and spawning behaviour between the sexes of L. pl 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 pair bond exists between partners of L. planeri 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 for L. pl a n e r i . 26. Intestines of ammocoetes of L. planeri contained pre-dominantly diatoms during the spring and summer, but detritus 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 River. 28. The skin of lampreys contains a protective substance that i s d i s t a s t e f u l to certain f i s h . 29. Length-frequency analysis should be carried out only on large samples taken from many differ e n t habitats and with many di f f e r e n t c o l l e c t i n g methods. 30. Ammocoetes of L. planeri 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 envir-onment to test length-frequency data and the presence of a rest period. 189 32. The growth curve of the ammocoetes of L. planeri and E. tridentatus i s very s i m i l a r for 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 for analysis of polymodal length-frequency d i s t r i b u t i o n and age determination for lamprey populations. 190 LITERATURE CITED Applegate, V.C., 1950a. N a t u r a l h i s t o r y of the sea lamprey, Petromyzon marinus, i n Michigan. 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 the Great Lakes. Spec. S c i . Rept. U.S. F i s h W i l d l . Serv. 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 of f i s h behaviour. The Physiology of Fi s h e s , Edited by M.E. Brown, Academic Press, New York, London, V o l : I I . Berg, L.S., 1931. A review of the lampreys of the northern hemisphere. Annuaire Du-Mussee Zoologique De. L vAcademic Des Science De L'urss, V o l . XXXII: 87-116. Beverton, J.H., and S.J. H o l t , 1956. On the dynamics of e x p l o i t e d f i s h populations. Her Majesty's S t a t i o n e r y O f f i c e , London. C a r l , C.G., 1953 . E c o l o g i c a l survey of Cowichan R i v e r and t r i b u t a r i e s . Journ. F i s h . Res. Bd. of Can. 6 (1): 28-39. C a r l , C.G., W.A. Clemens, and C.C, Lindsey, 1959. The fresh-water f i s h e s of B r i t i s h ' C o l u m b i a . B r i t i s h Columbia P r o v i n c i a l Museum, Handbook No. 5= 25 - 3 0 . Cassie, R.M., 1954. Some use of p r o b a b i l i t y paper i n the a n a l y s i s of s i z e frequency d i s t r i b u t i o n . A u s t r a l i a n J . Marine and Fresh-water Res. 5: 513-522. C h u r c h i l l , W.S., 1947. The brook lamprey i n the Brule R i v e r . Trans. Wise. Acad. S c i . , A r t s and L e t t . , 37: 337-346. Coots, M i l l a r d , . 1955• The P a c i f i c lamprey , Entosphenus, above Copco Dam, S i s i y o u , County Gal. CaT! F i s h and Game, 41 (1): 18. Creaser, .C.W.. , and C.S. Hann, 1929. The food of l a r v a l lampreys. Papers Mich. Acad. S c i . , Arts and L e t t . , .10: 433-437.' ; . , W ;• .--. Creaser, C^W-^and G.L. Hubbsyi#192^ -:--A/: r e v i s i o n - of - the H o i a r c t i c uampreys. Oct'. Papers*Mils. Zool,.,, Univ. * . Mich. No. 120.: 1^4. i:'-'- '  ;:7':° ! ' . " " M = -191 Dean,'B., and F.B. Summer, I 8 9 8 . Notes on the spawning habits of the brook lamprey (Petromyzon w i l d e r i ) . Trans. N.Y. Acad. S c i . : 331-334. Dendy, J.S., and D.C. Scott, 1953. D i s t r i b u t i o n , l i f e h istory and morphological varia t i o n of the southern brook lamprey. Copeia for 1953, ( 3 ) : 152. Enequist, P., 1937. Das Bachneunauge als okologische Modifikation des Flussneunauge. Ueber die Arkiv. Zool., 29:20: 1-22. Gage, S.H., 1893- Lake and brook lampreys of New York, especially those'of Cayuga and Seneca Lakes. Wilder Quarter Century Book, Comstock Pub. Co., Ithaca, New York: 421-493-Gage, S.H., 1928. The lampreys of New York State, l i f e h istory and economics of the Oswega River system. Rep. N.Y. St. Conserv. Dept. Suppl. t . 17th-: 158-91. Guibe, 1958. restated by Grasse, P.P., Traite de Zoologie Tome XIII Paris: 1934-Hagelin, L.O., 1959. Further aquarium observations on the r i v e r lamprey. Oikos 10 (1): 50-63. Hagelin, L.O., and N. Steffner, 1958. Notes on the spawning habits of the r i v e r lamprey (P. f l u v i a t i l i s ) . Oikos 9 (2): 222-238. Hardisty, M.W., 1944. The l i f e history and growth of the brook lamprey, Lampetra planeri. J. Anim. Ecol. 13: 110-122. 1951- Duration of the l a r v a l period i n the brook lamprey, Lampetra p l a n e r i . Nature, Lond. 167: 38. 1954- Sex r a t i o i n spawning populations of Lampetra planeri. Nature, Lond.: 173-874-, 1957- Embryonic and early l i f e of the brook lamprey. J. Exp. B i o l . , Vol. 34: 237-252. , 1961a. Studies on an isolated spawning population of brook lampreys (Lampetra planeri) J. Anim. Ecol. 30: 339-355. / , 196lb. Oocyte counts as a diagnostic character for the i d e n t i f i c a t i o n of ammocoete species. Nature, Lond. 191: 1215-1216. , 196lc. The growth of larval lampreys. J. Anim. Ecol. 30: 357-371. 192 Hardisty, M.W., 1963. Fecundity and speciation i n lampreys. Evolution Vol. 17: 17-22. Horton, F.M., 1934. On the r e l a t i o n of the thyroid gland to metamorphosis i n the lamprey. J. Exp. B i o l . I I : 257-261. Hubbs, C.L., 1924. The l i f e cycle and growth of lampreys. Pap. Mich. Acad. S c i . 4 (5): 87-603-Hubbs, C.L., and M.B. Trautman, 1937. A revisi o n of the lamprey genus Ichthyomyzon. Misc. Publ. Mus. Zool. Univ. Michigan. No. 35M-109-Hurn, D.R., 1962-63. B r i t i s h Columbia Fish and Game Branch, Regional B i o l o g i s t . Verbal communication and use of unpublished data. Ivanova- Berg, 1931. Uber f i e lebendauer der larve von Lampetra planeri aus dem Gebiete des Finneschen Busens. Zool. Anz. 96: 330-334. Jones, F.R. Harden, 1955. Photo-kinesis i n the ammocoete larva of the brook lamprey. J. Exp. B i o l . 32: 492. Kelley, CC. and R.H. Spilsbury, 1939. S o i l survey of the lower Fraser Valley. Can. Dept. Agt. Pub. # 650, Tech. B u l l . 20. Kennedy, W.A., 1956. Summary report Fisheries Research Board of Canada, B i o l o g i c a l Station, London, Ontario. Kleerekoper,H., 1958. The l o c a l i z a t i o n of prey by the sea lamprey, Petromyzon marinus. The Anatomical Record. Vol. 132 (3): 464. Kleerekoper, H., and G.A. van Erkel, I960. The olfactory apparatus of Petromyzon marinus. Can. J. Zool. 30: 211-222. Kleerekoper, H., G. Taylor, and R. Walton, 1962. Diurnal p e r i o d i c i t y i n the a c t i v i t y of Petromyzon marinus and the effect of chemical stimulation. Trans. Amer. Fish Soc. Vol. 90 (1). Knowles, F.G.W., 1941. The duration of l a r v a l l i f e i n ammocoetes and an attempt to accelerate metamorphosis by in j e c t i o n s of an anterior p i t u i t a r y extract. Zool. Soc. Lond. P r o c , Ser. A. , 1940-42, 110-111:' 101-109. Lack, D., 1954. The natural regulation of animal numbers. Oxford, Clarendon Press. Leach, W.J., 1940. Occurrence and l i f e history of the northern brook lamprey (Ichthyomyzon fossor )in Indiana. Copeia f or 1940, ( l ) : 21-34-193 Lennon, Robert E., 1955- A r t i f i c i a l propagation of the sea lamprey, P. marinus. Copeia. 1955 No. 3: 235-236. Lindsey, C.C., University of B r i t i s h Columbia. Personal communication. 1961. Loman, J.C., 1912. Uber die Geschlechts differenzierung bei Ammocoetes. Verh. Anat. Ges. Vers. 17: 66-74. MacDonald, T., 1957. Ammocoete behaviour. Summary report Fisheries Research Board of Canada, B i o l o g i c a l Station, London, Ontario. MacDonald, T.H., 1959. Estimates of the length of l a r v a l l i f e . i n three species of lamprey found i n B r i t a i n . J. Anim. Ecol. 28 (2) 293-298. McLain, A.L., 1951. Diseases and parasites of the sea lamprey, Petromyzon marinus, i n the Lake Huron basin. Trans. Amer. Fish. S o c , Vol. 81: 94-100. McMynn, R.G., and E.H. Vernon, 1954. Some physical and b i o l o g i c a l observations on the Salmon River- Fort Langley. B.C. Game Commission Report. Mansuet, R.J., 1962. D i s t r i b u t i o n of small newly metamorphosed sea lamprey, Petromyzon marinus, and t h e i r parasitism on menhaden, Brevoortia tyrannus, i n Mid-Chesapeake Bay during Winter months. Chesapeake S c i . 3 (2):137-139. Milne, D., I960. P a c i f i c B i o l o g i c a l Station, Nanaimo, B.C., personal communication. Newth,.H.G., 1930. The feeding of ammocoetes. Nature (London), 126 (3168): 94-95. Okkelberg, P., 1922. Notes on the l i f e history of the brook lamprey, Ichthyomyzon unicolor. Pap. Mus. Zool. Univ. Michigan. 522 (9): 125. Perlmutter, A., 1951. An aquarium experiment on the American eel as a predator on l a r v a l lampreys. Copeia (2): 173-174. P f e i f f e r , W., i960. Uber die Verbreitung der schreckreaktion bei fischen. Naturwiss enschaften, 47: 23; also i n B u l l . Sta. b i o l . Arcachon, No. 12. P i a v i s , G.N., i960. Embryonic stages i n the sea lamprey and effects of temperature on development. Fisheries B u l l e t i n 182. U.S. Dept. of the I n t e r i o r Fish and W i l d l i f e Service. Pickford, G.E., and J.W. Atz, 1957. The physiology of the p i t u i t a r y gland of fish e s . New York Zoological Society, New York: 117-121. 194 Pike, G.C., 1951' Lamprey marks on whales. J. Fj_ sh. Res. Bd. Canada. 84. ,1953. The P a c i f i c sea lamprey. Progress Reports of the P a c i f i c Coast. Station of the Fisheries Research Board of Canada, No. 97= 3-5. Raney, E., 1939. The breeding habits of Ichthyomyzon greenleyi (Hubbs and Trautman). Copeia 2: l i l - 1 1 2 . Regan, C.T., 1911. A synopsis of the marsipobranchs of the order Hyperoartii. Ann. Mag. Nat. Hist., Ser. 8, 7: 193-204-Reighard, J,, and H. Cummins, 1916. Description of a new species of lamprey of the genus Ichthyomyzon. Occ. Pap. Mus. Zool., Univ. Mich., (3): 12. Remy, P., 1942. L'iode et l a metamorphose de 1'ammocoete branchialis et Petromyzon planeri (Bloch). CR. Soc. B i o l . P a r i s , 86: 129-131-Rensch, 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. Fisheries 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 for 1959, (3): 256-257-S c h r o l l , F., 1959- Zur enahrungsbiologie der steirischen ammocoten Lampetra planeri (BlochT und Eudontomyzon  danfordi (Regen). Int. Rev. Ges. Hy d r o l i n l . , 44 (3) '• 395-421. Schultz, L.P., 1930. The l i f e history of L. planeri (Bloch) with a s t a t i s t i c a l analysis of the rate of growth of the larvae from western Washington. Occ. pap. Mus. Zool., Univ. Mich., (221): 1-35-Scott, 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 Station and the Technological Unit, London, Ontario, 1956-57. Stauffer, T.M., 1962. Duration of l a r v a l l i f e of sea lampreys in Carp Lake River, Michigan. Trans. Amer. Fish. Soc. Vol. 91 (4): 422-423. Surface, H.A., 1897. The lamprey of central New York. B u l l . U.S. Fish. Comm. 17: 209-215. 195 Thomas, J . ^ . , 1 9 6 2 . The food and growth of brown t r o u t (Salmo t r u t t a ) and i t s feeding r e l a t i o n s h i p s w i t h the salmon parr (Salmo s a l a r L.) and the e e l ( A n g u i l l a  a n g u i l l a L.) i n the R i v e r Terfy, West Wales. Journal Animal Ecology: 3 1 * Thomas, M.L.H., 1 9 6 3• Studies on the bio l o g y of ammocoetes i n streams. Manuscript 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. Vladykov, V.D., 1951. Fecundity of Quebec lampreys. 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 zanandreai, a new species of lamprey from Northern I t a l y . Copeia, 1955. 3: 215-223. Vladykov, 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 of Lampetra a y r e s i i (Gunther) of Western North America, a species of lamprey (Petromyzontidae) 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. Wickett, 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. Personal communication and use of unpublished data. Wigley, R.L., 1952. A method of marking l a r v a l lampreys. Copeia, 1952. No. 3 : 2 0 3 - 2 0 4 . ,1959. L i f e h i s t o r y of 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 Serv. F i s h B u l l . 59 (154): 561-617. Young, J.Z., 1935. The photoreceptors of lampreys. 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 nerves. 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 of the lamprey to i n j e c t i o n s Of a n t e r i o r lobe 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 (Bloch). 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 Pesca, 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. XXVII, 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. Studies oh European lampreys. E v o l u t i o n , 15 (4): 523-534. 

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