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Behavioural ecology of chum salmon (O.keta) and coho salmon (O. kisutch) alevins in the gravel Dill, Lawrence Michael 1967

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BEHAVIOURAL ECOLOGY OP CHUM SALMON (0. KETA) AND COHO SALMON (0. KISUTCH) A LEVINS IN THE GRAVEL by LAWRENCE MICHAEL DILL B . S c , U n i v e r s i t y o f B r i t i s h Columbia, 1966 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n t h e Department o f Z o o l o g y We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o the r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA October, 1967 In 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 o f t h e r e q u i r e m e n t s f o r a n . a d v a n c e d d e g r e e a t t h e U n i v e r s i t y o f B r i t i s h ' C o l u m b i a , I a g r e e t h a t t h e 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 r e f e r e n c e and S t u d y . I f u r t h e r a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d b y t h e Head o f my D e p a r t m e n t o r b y h iis r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l n o t be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . D e p a r t m e n t The U n i v e r s i t y o f B r i t i s h C o l u m b i a V a n c o u v e r 8, C a n a d a D a t e H o N f t W l h o x 8 J ABSTRACT An integrated laboratory and f i e l d approach was used to study the behaviour and ecology of P a c i f i c salmon (genus Oncorhynchus) alevins i n the gravel. The hypothesis tested was that these yolk sac f r y move throughout the gravel p r i o r to emergence, that t h i s movement has both l a t e r a l and v e r t i c a l components, and that changes i n the physical or b i o l o g i c a l environment w i l l a l t e r c e r t a i n parameters of subgravel behaviour. Eyed chum salmon (0. keta) eggs were buried i n incubation channels at Robertson Creek, B. C. Eight experimental treatments were chosen, u t i l i z i n g two gravel s i z e s , two b u r i a l depths and two planting d e n s i t i e s . The fry were captured at emergence by means of s p e c i a l l y designed traps that allowed determination of degree of l a t e r a l movement, pattern of emergence and s u r v i v a l to emergence. The f r y were also sampled f o r condition (weight-length r a t i o ) at the time of emergence. In the larger gravel, s u r v i v a l was greater, l a t e r a l movement was increased, and i n i t i a l emergence was e a r l i e r . At the greater b u r i a l depth the emergence period was longer. At the greater b u r i a l density i n i t i a l emergence was e a r l i e r . Condition at emergence was the same i n a l l treatments. The behaviour of coho salmon (0. kisutch) alevins was examined i n s p e c i a l l y constructed aquaria, where l i g h t and flow conditions were as natural as po s s i b l e . The same environmental factors were varied as i n the f i e l d . In addition to a general description of al e v i n behaviour, detailed analyses were c a r r i e d out on: v e r t i c a l and l a t e r a l movement, orientation, s p a t i a l d i s t r i b u t i o n , condition, survival and pattern of emergence. In the larger gravel v e r t i c a l and l a t e r a l movements were increased, survival was higher, area u t i l i z a t i o n was greater and condition at emergence was poorer. At the greater b u r i a l depth l a t e r a l movement towards the outlet was increased and i n i t i a l emergence was e a r l i e r . V e r t i c a l movement was decreased because more f r y were trapped within the gravel. At the higher density the alevins moved farther towards the i n l e t . The mean area occupied per alevin was unchanged by density and suggests competition within the gravel. The orientation of the alevins i s discussed in r e l a t i o n to l i g h t and current. The results indicate that larger gravel i s better than smaller gravel f o r the incubation of P a c i f i c salmon. B u r i a l depth seems unimportant, but should be great enough to prevent predation. The question of optimum density requires further study. Emergence patterns may apparently be modified through environmental c o n t r o l . - i v TABLE OP CONTENTS ABSTRACT TABLE OP CONTENTS LIST OP FIGURES LIST OF TABLES ACKNOWLEDGEMENTS INTRODUCTION METHODS FIELD STUDY Trapping F a c i l i t i e s and Techniques Analysis of Results ( i ) distance of migration through the gravel ( i i ) condition at emergence ( i i i ) s u r v i v a l to emergence (iv) pattern of emergence Physical Factors LABORATORY STUDY Experimental Aquaria and Design Observations ( i ) daytime ( i i ) night time Analysis of Results ( i ) movement i n the gravel ( i i ) orientation i n the gravel ( i i i ) s p a t i a l d i s t r i b u t i o n i n the gravel (iv) condition at emergence (v) s u r v i v a l to emergence (vi) pattern of emergence Physical Factors ( i ) water temperatures ( i i ) oxygen concentrations ( i i i ) subgravel flow -V-Page RESULTS FIELD STUDY Distance of M i g r a t i o n 27 C o n d i t i o n of Emergence 27 S u r v i v a l to Emergence 27 P a t t e r n of Emergence 32 P h y s i c a l Factors ( i ) oxygen concentrations 36 ( i i ) water temperatures 37 LABORATORY STUDY 37 Behaviour of A l e v i n s i n the Experimental Aquaria 37 Degree o f V e r t i c a l Movement ij.6 Degree of L a t e r a l Movement lj.6 O r i e n t a t i o n i n the Gr a v e l 53 S p a t i a l D i s t r i b u t i o n i n the Gravel 57 Condition at Emergence 57 S u r v i v a l t o Emergence 62 P a t t e r n o f Emergence 62 P h y s i c a l Factors ( i ) temperature 66 ( i i ) oxygen concentrations 66 ( i i i ) subgravel flow 66 DISCUSSION E f f e c t of Gravel Size 70 E f f e c t of B u r i a l Depth 72 E f f e c t of Egg Density 73 Responses of the A l e v i n s to Light jl$ Responses of the A l e v i n s to Current 76" Optimal Conditions of P l a n t i n g 76 LITERATURE CITED 79 - v i -LIST OP FIGURES FIGURE Page 1 Concentric r i n g traps at Robertson Creek. 7 2 Another view o f the same t r a p s , showing ducts and bags. 7 3 Schematic r e p r e s e n t a t i o n of the c o n c e n t r i c r i n g t r a p s i n s t a l l e d at Robertson Creek, B. C. 8 l\. Experimental design, Robertson Creek t r a p s . 11 5 V-screen i n operation at Robertson Creek. . 12 6 Schematic r e p r e s e n t a t i o n of experimental aquarium. 18 7 Experimental design, aquaria i n l a b o r a t o r y . 19 8 Mean d a i l y water temperatures -Robertson Creek - May + June, 1967 38 9 Phases i n the behaviour o f the a l e v i n s i n the large g r a v e l , a. a l e v i n moving down-ward 3 days a f t e r h a t c h i n g ; b. a l e v i n s aggregated on the tank bottom, 5 days a f t e r hatching; c. a l e v i n s d i s p e r s i n g along the tank bottom, 31 days a f t e r h a t c h i n g ; d. f r y near emergence, I4.I days a f t e r h a t c h i n g ; e. newly emerged f r y , 36 days a f t e r h a t c h i n g . 39 10 Phases i n the behaviour of the a l e v i n s i n the small g r a v e l , a. a l e v i n s beginning to d i s p e r s e , 1 day a f t e r h a t c h i n g ; b. a l e v i n near the tank bottom, I4.2 days a f t e r h atching; c. d i s p e r s i o n o f the a l e v i n s , 1+2 days a f t e r h a t c h i n g . I4.2 11 Nocturnal movement o f coho salmon a l e v i n s (53 days a f t e r hatching) i n the sm a l l g r a v e l of the experimental a q u a r i a . Upper: 2100 hours ( l i g h t s o f f at 2030 hours); Lower: 2l±00 hours. l±$ v i i -FIGURE Page 12 Mean v e r t i c a l p o s i t i o n s of the a l e v i n s i n the large g r a v e l . Upper - 8 i n c h b u r i a l depth, lower - 12 i n c h b u r i a l depth. L e f t side - egg de n s i t y 50, r i g h t side -egg d e n s i t y 100. lj.8 13 Mean l a t e r a l p o s i t i o n s o f the a l e v i n s i n the la r g e g r a v e l . Upper - 8 i n c h b u r i a l i depth, lower - 12 i n c h b u r i a l depth. L e f t side - egg de n s i t y 50, r i g h t side -egg den s i t y 100. 51 11}. Graph of the area occupied by the a l e v i n s i n the large g r a v e l . Upper - 8 i n c h b u r i a l depth, lower - 12 i n c h b u r i a l depth. L e f t side - egg d e n s i t y 50, r i g h t side - egg d e n s i t y 100. 59 15 Mean d a i l y temperatures Laboratory - A p r i l to J u l y , 1967. • 67 16 Subgravel flow through the experimental a q u a r i a . 68 v i i i LIST OP TABLES TABLE Page I. Mean Distance (Ft.) of Alevin Migration from Point of Deposition i n Concentric Ring Traps at Robertson Creek. 28 I I . Condition Factor (k) f o r Fry Emerging within Concentric Ring Traps. See Text f o r Calculation of "k". 29 I I I . A Comparison of the Weights and Lengths of the Fry Produced i n Channel 8 with Those of the Dyed Fish Introduced to the Channel and Recaptured. 31 IV. Number of Days a f t e r Planting at which the F i r s t Fry Appeared i n the Concentric Ring Traps. 3k V. Number of Days a f t e r Planting at which the Last Fry Disappeared from the Concentric Ring Traps. 3k-VI. Length of the Emergence Period (Days) i n the Concentric Ring Traps. 35 VII. Percent of Possible Downward Movement in the Experimental Aquaria. Ii7 VIII. Percent of Possible Upward Movement in the Experimental Aquaria. 50 IX. Extent of Lateral Movement to the Outlet (Expressed as Inches from Center) i n the Experimental Aquaria. 5U X. Extent of Lateral Movement to the Inlet (Expressed as Inches from Center) i n the Experimental Aquaria. 5^4-XI. Total Lateral Movement (Expressed as Inches from Center) i n the Experimental Aquaria. 55 XII. Mean Orientation Direction by Time Period, f o r Each Treatment i n the Experimental Aquaria. Directions are Expressed as Angles, Counterclockwise from Top Center. 56 -ix-TABLE X I I I . XIV. XV. XVI. XVII. X V I I I . Page Mean Angle o f O r i e n t a t i o n i n the Gr a v e l , Expressed as Degrees, Counterclockwise from Top Center. 58 The Maximum Area U t i l i z e d Per A l e v i n i n the Experimental A q u a r i a . Expressed as • Square Inches Per A l e v i n V i s i b l e . 61 C o n d i t i o n I n d i c e s (k) o f the Fry Emerging from the Experimental A q u a r i a . 63 Percent S u r v i v a l to Emergence i n the Experimental A q u a r i a . 61). lumber of Days a f t e r P l a n t i n g to F i r s t Emergence i n the Experimental Aquaria. 65 The E f f e c t s o f In c r e a s i n g Gravel S i z e , B u r i a l Depth, and Egg Density on the Parameters Measured i n the Study. 71 ACKNOWLEDGEMENTS The a u t h o r w i s h e s t o e x p r e s s h i s g r a t i t u d e t o the f o l l o w i n g groups and i n d i v i d u a l s : - Mr. D. MacKinnon, C h i e f B i o l o g i s t , Department o f F i s h e r i e s , f o r s u g g e s t i n g the p r o b l e m . - D r . J . T. MacFadden, now a t U n i v e r s i t y o f M i c h i g a n , f o r the e x p e r i m e n t a l d e s i g n . - the Department o f F i s h e r i e s o f Canada, f o r f i n a n c i a l s u p p o r t . - M e s s r s . P. Ryan, Department o f F i s h e r i e s E n g i n e e r , and G. M c C u l l o c h , U.B.C. Z o o l o g y T e c h n i c i a n , f o r t h e i r a s s i s t a n c e w i t h a p p a r a t u s d e s i g n . - f e l l o w s t u d e n t s R. B r o c k , B. A y l e s , A. T a u t z , R. Nagano, P. Reimers, and p a r t i c u l a r l y B. D a v i e s , f o r t h e i r h e l p w i t h a p p a r a t u s c o n s t r u c t i o n . - M e s s r s . J . Ba k e r and G. C l o u t h i e r , f o r t h e i r a s s i s t a n c e w i t h f i e l d d a t a c o l l e c t i o n . - Department o f F i s h e r i e s B i o l o g i s t s R. Palmer, C. Wa l k e r , R. K. K e a r n s , and B. L i s t e r f o r t i m e l y a i d d u r i n g the p r o j e c t . - Dr. T. G. N o r t h c o t e , my f a c u l t y a d v i s o r , f o r h i s a d v i c e and a s s i s t a n c e . - D r s . J . M a c P h a i l , N. R. L i l e y and W. S. Hoar f o r t h e i r c r i t i c a l r e v i e w o f t h e m a n u s c r i p t . - M r s . M. E. T r e b e t t , e d i t o r o f t h e Twin C i t i e s Times, A l b e r n i , B. C., f o r F i g u r e 1. - M i s s J . Towers f o r t y p i n g t h e m a n u s c r i p t and J . S t e f a n i u k f o r the f i g u r e s . - My w i f e , f o r h e r c o n s t a n t a s s i s t a n c e and encouragement. The work was u n d e r t a k e n w h i l e the a u t h o r was the r e c i p i e n t o f a N a t i o n a l Research C o u n c i l o f Canada B u r s a r y . INTRODUCTION Most phases of the l i f e h i s t o r y of P a c i f i c salmon are w e l l understood as a r e s u l t of the e f f o r t s of countless i n v e s t i g a t o r s during the past century. The a l e v i n , however, has not r e c e i v e d the a t t e n t i o n that i t deserves. The present study i s an attempt to c o n t r i b u t e some knowledge of t h i s p e r i o d of the l i f e - c y c l e . The eggs of the P a c i f i c salmon, l i k e those of most salmonids, are l a i d i n an excavation i n the stream bed (a redd) and are then covered by g r a v e l from an excavation dug by the female immediately upstream. The eggs are t y p i c a l l y covered by many inches of g r a v e l and a f t e r hatching the larvae ( a l e v i n s ) must work t h e i r way to the surface from t h i s depth, w i t h the y o l k sac a t t a c h e d . Once the y o l k sac has been absorbed, the young f i s h i s c a l l e d a f r y . The terminology i s t h a t of L a g l e r (1956). From hatching to emergence, the a l e v i n may spend up to two months w i t h i n the g r a v e l bed. That t h i s p e r i o d o f the l i f e h i s t o r y has received but scant a t t e n t i o n i s s u r p r i s i n g , since i t i s w e l l accepted that m o r t a l i t y i n the e a r l y l i f e of the salmon plays a key r o l e i n determining adult p o p u l a t i o n d e n s i t y , and therefore the commercial value of a p a r t i c u l a r stock of f i s h (Neave, 1953; Royce, 1959). Much work has r e c e n t l y been c a r r i e d out concerning the environmental requirements o f salmonid a l e v i n s . Wickett (19514-), Gangmark and Bakkala (I960), Coble (1961) and McNeil (1962) have - 2 -demonstrated that the rate of flow of the water within the gravel, as well as the quality of the water i t s e l f , are of great importance to the s u r v i v a l of the eggs, embryos, and alevins within the gravel bed. In the laboratory, Alderdice et a l . (1958), S i l v e r et a l . (1963), Shumway et a l . (1961;) and Brannon (1965) demonstrated the e f f e c t s of d i f f e r e n t concentrations of dissolved oxygen and water v e l o c i t i e s on survival and growth of salmonid a l e v i n s . Gangmark and Bakkala (I960), Sheridan and McNeil (I960), and McNeil (1962) demonstrated that the s t a b i l i t y of the redd gravel was an important factor i n determining s u r v i v a l to emergence. Harrison (1923), Shapovalov and Berrian (19l|.0), Shaw and Maga (19ir3), Neave (19lj7), Stuart (1953), Campbell ( 1 9 5 U , Cordone and Kelly (1961), Bianchi (1963), Cooper (1965), P h i l l i p s (1965), and Shelton and Pollock (1966) have a l l demonstrated the detrimental e f f e c t s of sedimentation on salmonid embryos and alevins which result from reduced flow and oxygen concentrations in the g r a v e l . Many authors have examined survival to emergence from the gravel. These include C a r l (19i|0), White (191^2), Shaw and Maga (1943 ), Pritchard (19^7 ), Hobb s (19^8), Briggs (1953), Poerster and Ricker (1953), Wales and Coots (1955), Hunter (1959), P h i l l i p s and Campbell (I96I), Coble (1961), McNeil (1962, I963, and 1966), M e r r e l l (1962), Wickett (1962), McNeil and Ahnell (19614.), and Koski (1966). The above studies demonstrated that s u r v i v a l to emergence varies widely, from zero to 100 percent, and that i t i s higher f o r coho and chinook salmon than for chum, -3-pink and sockeye. S u r v i v a l appears to be l a r g e l y dependent on the oxygen a v a i l a b i l i t y i n the g r a v e l , which i n turn depends on water v e l o c i t y and g r a v e l p e r m e a b i l i t y . I t may be that d i f f e r e n t species have d i f f e r e n t v i a b i l i t i e s , i n that one can survive c o n d i t i o n s which would cause heavy m o r t a l i t y i n another. The behaviour of the a l e v i n has been s t u d i e d by o n l y a few a u t h o r s . White (1915), Woodhead (1957) and Heard (196ii) examined the responses of salmonid a l e v i n s to l i g h t before and during emergence. B i s h a i ( I 9 6 0 , 1961a, 1961b, 1962a, 1962b) examined the o r i e n t a t i o n of salmonid larvae w i t h respect to water c u r r e n t s , s a l i n i t y , pH, pressure, and oxygen c o n c e n t r a t i o n s . Stuart (1953) raade observations of migrations through the g r a v e l of the a l e v i n s of the Loch t r o u t (Salmo t r u t t a L . ) , while Marr (I963) reported on the i n f l u e n c e of surface contour on t h e i r behaviour. Roth and Geiger ( I 9 6 3 ) , and Geiger and Roth (I962) examined the responses o f brown trout a l e v i n s to g r a v i t y , l i g h t , and c u r r e n t while i n the g r a v e l bed. R. Bams, of the F i s h e r i e s Research Board o f Canada, has conducted s i m i l a r unpublished experiments on the a l e v i n s of the sockeye salmon (Qncorhynchus  ne r k a ) . Much of the above mentioned work i s incomplete and even c o n t r a d i c t o r y , but, i n t o t o , suggests that salmonid a l e v i n s do indeed move through the g r a v e l p r i o r to emergence. These movements may have a pronounced v e r t i c a l component, the a l e v i n s moving downward p r i o r to t h e i r upward migr a t i o n t o the g r a v e l surface (Roth and Geiger, 1963) . Stuart (1953) suggested that the movements have an important l a t e r a l component as w e l l , which Roth was unable to observe i n h i s c y l i n d r i c a l experimental observation chambers, since these allowed no l a t e r a l movement. Stuart (1953) s t a t e d that "migration... was i n a l a t e r a l d i r e c t i o n and never d i r e c t l y upwards. The a l e v i n s dispersed i n t o the g r a v e l . . . r a d i a t i n g upwards and outwards, and a p l o t of t h e i r r e l a t i v e p o s i t i o n s took the form of an i n v e r t e d cone ." This has since been corroborated by work done on coho salmon (0. keta) and steelhead t r o u t (S. g a i r d n e r i ) a l e v i n s i n Oregon (H. J . Campbell, p e r s . comm., I966). Shelton (1955) demonstrated that such parameters as s u r v i v a l to and c o n d i t i o n at emergence may be a l t e r e d by c o n d i t i o n s w i t h i n the redd. I t may be that such a l t e r a t i o n s are mediated through changes i n a l e v i n behaviour. The hypotheses t e s t e d i n the present study, then, were that the a l e v i n s of the P a c i f i c salmon move throughout the g r a v e l bed p r i o r to emergence, that t h i s movement has both l a t e r a l and v e r t i c a l components, and that changing the environment may a f f e c t subgravel behaviour. The environmental v a r i a b l e s chosen f o r the study were g r a v e l s i z e , egg b u r i a l depth, and egg d e n s i t y . Two l e v e l s o f each were used i n a 2x2x2 f a c t o r i a l design. Gravel s i z e and b u r i a l depth were chosen because of t h e i r importance i n the design of in c u b a t i o n and spawning channels. Emphasis i n the past has been placed s o l e l y on s u r v i v a l to emergence. I t i s not inconceivable that f a c t o r s such as b u r i a l depth and g r a v e l s i z e a f f e c t the area of g r a v e l r e q u i r e d by a group of a l e v i n s moving towards the s u r f a c e . I f there' i s competition f o r food or space i n the g r a v e l then the area occupied by a group o f a l e v i n s before or at emergence may determine how many eggs may be planted i n a channel without a f f e c t i n g subsequent s u r v i v a l . The d e n s i t y of p l a n t i n g was v a r i e d i n an attempt to determine whether competition a c t u a l l y occurs. Competition i s a d i s t i n c t p o s s i b i l i t y i f the a l e v i n s a c t i v e l y feed before emergence. Pre-emergent feeding has alr e a d y been i n d i c a t e d by the s t u d i e s of D i l l (I967), D i s l e r (1953), Burrows (pers. comm. 1965), P h i l l i p s (pers. comm. 1966), and o t h e r s . In the present study, an i n t e g r a t e d f i e l d and la b o r a t o r y approach was u t i l i z e d to provide as complete inf o r m a t i o n as p o s s i b l e on the e f f e c t s of the f a c t o r s examined. Since, under f i e l d c o n d i t i o n s , at l e a s t , i t was not p r a c t i c a l to c o n t r o l such aspects o f the environment as oxygen c o n c e n t r a t i o n , subgravel f l o w , and water temperatures, these v a r i a b l e s were measured i n order to at l e a s t be able to account f o r them i n d i s c u s s i n g the r e s u l t s of the experiments. -6-METHODS  FIELD STUDY Trapping F a c i l i t i e s and Techniques The f i e l d portion of the experiment was conducted at the Robertson Creek station of the Department of F i s h e r i e s of Canada, located near A l b e r n i , B r i t i s h Columbia. The f a c i l i t i e s included a series of small incubation channels, whose flow could be controlled by means of stoplogs at t h e i r upstream ends. Fry traps (Figs. 1, 2, and 3) were i n s t a l l e d i n two of these channels. The upper f i f t y feet of two adjacent channels was chosen and eight "concentric-ring traps" were i n s t a l l e d i n each. The traps were modified from a design used by H. J . Campbell of the Oregon State Game Commission (pera. comm.,1966). They consisted of five concentric rings of 18x16 mesh fiberglass screen, supported by lathes and placed at one-half foot i n t e r v a l s from each other. Each ri n g , therefore, had a diameter one foot larger than the one inside i t , the t o t a l diameter of each trap being 5 f e e t . The screens extended two inches into the gravel and 1-1/2 feet above the water surface ( F i g . 3)» Eggs of the chum salmon (Oncorhynchus keta) were obtained from several adult spawners in the Big Qualicum River, B r i t i s h Columbia, on December 9, 1966. They were mixed and held to the eyed stage at the Qualicum River Station of the Department of F i s h e r i e s . The eyed eggs were transported to Robertson Creek and buried there on February 17, 1967 by gently pouring them down a 3/V inch PVC standpipe into a p l a s t i c Vibert box. The boxes were p a r t i a l l y f i l l e d with gravel and had been -7-Figure 2. A n o t h e r v i e w of the same t r a p s , showing ducts and bags. Water Sur face LEGEND ELEVATION o o o 3 3 lO Q "O 1. 3 /4 inch P.V.C. s tandpipe, through which eggs were deposited. 2. Rubber stopper at base of s tandp ipe, to prevent fry exit. 3. Molded plastic Viber box to retain eggs but pass a lev ins. 4. Routes of alevin migrat ion through the gravel . 5. Concentr ic r ings of 18 x 16 mesh f i be rg lass sc reen . 6. Ent rance to duct via metal s leeve 7. Dryerflex hose duct, 4 inches in diameter. 8. Duct passing through 3 inch diameter hole in skirt of 3/16 in neoprene rubber. 9. Cotton bags with mesh ends , one per duct. 10. Gravel level. b u r i e d i n the channels the previous day. The s l o t s i n the side of each box were small enough to r e t a i n the eggs but large enough to a l l o w e x i t of the a l e v i n s . The standpipe was sealed w i t h a number 3 rubber stopper a t the p o i n t where i t entered the box, thus preventing emergence of f r y up the standpipe. A f o u r - i n c h diameter p l a s t i c duct was attached to each screen by means of a t i n sleeve p r o j e c t i n g from the downstream end. The duct was attached to the sleeve w i t h a clamp and then passed through a t h r e e - i n c h hole i n a piece of 3 / 6-inch neoprene rubber i n s e r t e d above the metal sleeves i n each of the other screens. Thus, the duct l e a d i n g from the i n s i d e r i n g passed through each of the other f o u r screens. The neoprene s k i r t s f i t t e d t i g h t l y around the ducts so no l o s s of f r y c o u l d occur between the two. Each trap had f i v e p i e c e s of ducting p r o j e c t i n g from i t s downstream end, and each duct ended i n a canvas bag w i t h a marquisette net bottom. I t was intended t h a t the f r y emerging i n each r i n g of the trap would f i n d t h e i r way i n t o the ducting and be captured i n the canvas bags. I t proved i m p o s s i b l e , however, to capture the f r y i n t h i s manner, e i t h e r because the f r y could not locate the entrance to the duct or because water v e l o c i t y i n the channels was not marked enough to h o l d them i n the bags. At any r a t e , the emerged f r y remained i n the r i n g s r a t h e r than moving out. A few may have even vacated the traps by r e - e n t e r i n g the g r a v e l and going under the screens. Consequently the only way to assess the distance of subgravel movement and the c o n d i t i o n of the emerging f r y was to remove them from the r i n g s at n i g h t , - 1 0 using a d i p n e t . This was done four times n i g h t l y ( 0 1 0 0 , 0 3 0 0 , O^ OO, and 0700 hours) between May 6 and May 1 9 , and twice n i g h t l y (0100 and 0300 hours) between May 20 and June 2 . The traps were also checked each morning at 0900 hours between May 6 and June 2 . By June 2 there were no f i s h l e f t i n the t r a p s . The 16 traps were placed i n the in c u b a t i o n channels as shown i n F i g . i i . Two l e v e l s of each o f three f a c t o r s were st u d i e d , r e s u l t i n g i n a 23 f a c t o r i a l design w i t h two r e p l i c a t i o n s . The large and small g r a v e l s i z e s were 2 inches to I4. inches, and 3/8 inches to 1-1/2 inches r e s p e c t i v e l y . The g r a v e l was graded and washed, and put in t o the two channels, one g r a v e l s i z e per channel, i n e a r l y January, 1967. The eggs were b u r i e d at e i t h e r 8-inch or 1 2-inch depths (measured to the middle of the V i b e r t boxes) and at a de n s i t y of e i t h e r 50 or 100 eggs per t r a p . A t o t a l of 1200 eyed eggs was deposited i n the two channels. Campbell (pers. comm., I 9 6 6) reported that coho salmon and steelhead t r o u t a l e v i n s moved a maximum of 17 inches l a t e r a l l y when b u r i e d 10 inches i n the g r a v e l . I t was assumed, t h e r e f o r e , that the traps at Robertson Creek, being f i v e f e e t i n diameter, would catch a l l of the emerging f r y . To a s c e r t a i n t h i s , and to assess any p o s s i b l e leakage from the r i n g t r a p s , v-screens ( i n c l i n e d - p l a n e t r a p s ) were placed across each channel f i f t y feet below the downstream r i n g trap and l i n e d w i t h polyethylene sheeting,on a l l sides to prevent f u r t h e r leakage ( F i g . 5 ) . They were checked d a i l y from A p r i l 27 to June 2 , u s u a l l y at O83O hours i n the morning. A l l o f the chum f r y captured were recorded and preserved. One hundred chum f r y were dyed w i t h Bismarck brown -12-F i g u r e 5» V - s c r e e n i n o p e r a t i o n a t R o b e r t s o n C r e e k . and placed i n each channel on May ij. at 2330 hours. These dyed f r y were recorded i n the v-screen captures and used t o determine the e f f i c i e n c y of the two t r a p s . A n a l y s i s of Results An appendix g i v i n g d a i l y t a b u l a t i o n of a l l the Robertson Creek data i s a v a i l a b l e . Copies are on f i l e w i t h the Department of F i s h e r i e s , Resource Development Branch i n Vancouver Dr. T. G. Northcote at the U n i v e r s i t y of B r i t i s h Columbiaj and the author. ( i ) d istance of mig r a t i o n through the g r a v e l The f i s h i n each screened area were recorded as noted above. Appearance i n r i n g s A, B, C, D, and E ( F i g . 3) was taken to r e v e a l movement from the point of d e p o s i t i o n of .25, .75, 1.25, 1*75, and 2.25 f e e t r e s p e c t i v e l y . A mean distance o f mi g r a t i o n w i t h i n each trap was c a l c u l a t e d f o r each day and a composite value was determined f o r the e n t i r e emergence p e r i o d . The l a t t e r was then analyzed f o r d i f f e r e n c e s r e s u l t i n g from treatments, using the Yates t a b u l a r method of f a c t o r i a l a n a l y s i s o u t l i n e i n Davies (1956). I f P <C»05 *ke data was considered s i g n i f i c a n t . Since r e p l i c a t e s of three treatments were l o s t , no attempt was made to estimate them. I f two r e p l i c a t e s o f a treatment were a v a i l a b l e they were averaged to provide the values used i n the a n a l y s i s . ( i i ) c o n d i t i o n at emergence A l l f r y captured were preserved i n ten percent f o r m a l i n . A f t e r a p e r i o d of at l e a s t two weeks they were -111.-measured to the nearest m i l l i m e t e r and then d r i e d i n a 37 C oven f o r 2i\. hours before being weighed t o the nearest m i l l i g r a m on an e l e c t r i c balance. The data f o r both weight and l e n g t h were tab u l a t e d and summed over the e n t i r e p e r i o d of emergence f o r each r i n g and each t r a p . A c o n d i t i o n f a c t o r (k) was then determined f o r each trap by us i n g the f o l l o w i n g formula (modified from L a g l e r , 1956): , _ WEIGHT x 10 6 3 LENGTH These were analyzed by the Yates t a b u l a r method. R e p l i c a t e s of f i v e treatments were l o s t and no attempt was made to estimate them. I f both r e p l i c a t e s of a treatment were a v a i l a b l e , they were averaged as above. ( i i i ) s u r v i v a l to emergence Percent s u r v i v a l from each trap was determined s o l e l y from the number of f r y captured. The number seen i n the t r a p s was o f t e n g r e a t e r than t h i s , however, and some f r y were obviously being l o s t , even through the v-screens. At the te r m i n a t i o n of the experiment, each V i b e r t box was removed and the contents examined and enumerated. ( i v ) p a t t e r n o f emergence I t was not p o s s i b l e to compare d i r e c t l y emergence patterns between treatments since many f r y were l e f t i n the tr a p s f o r days and perhaps weeks before they were f i n a l l y captured w i t h the d i p n e t . The only parameters examinable w i t h regard to emergence p a t t e r n were: (1) date o f f i r s t f r y observed i n t r a p ; (2) date that l a s t f r y disappeared from t r a p ; -15-and (3) length of emergence period. Any differences in these parameters were also analyzed by the Yates tabular method of f a c t o r i a l a n a l y s i s , summing over two r e p l i c a t e s when a v a i l a b l e . Due to an inordinately small piece of data (a one day emergence period i n one trap compared to an average of 10.8 for the others) the data were also summed over the main e f f e c t s (for example, the two gravel sizes) and s i g n i f i c a n t differences revealed by means of Student's t- t e s t (Steel and Torrie, I960). Physical Factors Although the surface flows i n the two channels were controlled and equal, i t was thought possible that dissolved oxygen l e v e l differences might influence the parameters studied. Eight water samples, therefore, were taken on A p r i l 27, and another four on June 11. These were obtained by means of a s t a i n l e s s s t e e l b a r r e l syringe with a probe end inserted ten inches into the gravel through a 3/k inch PVG standpipe. The samples were placed i n 300 ml BOD bottles and analyzed by the standard, unmodified Winkler technique. Organic material proved troublesome i n three of the samples taken on A p r i l 27 and these were not considered i n the a n a l y s i s . Water temperatures were taken i n a l l of the standpipes on A p r i l 27 but from May 6 to June 2 the temperature was taken in only one standpipe at each observation time. Flow through the gravel was not considered in t h i s study, although P. Ryan (pers. comm., 1966) found that i t averaged .31 to .38 f t ./min. i n mixed gravel at Robertson Creek. -16-In t h i s study, no comparison of flow was made between the two g r a v e l s i z e s . LABORATORY STUDY This p o r t i o n of the study was conducted i n a s p e c i a l l y b u i l t l a b o r a t o r y at the U n i v e r s i t y of B r i t i s h Columbia. Eggs of the coho salmon (Oncorhynchus k i s u t c h ) were used. The eyed eggs were obtained from the excavation of a s i n g l e redd i n a sub-channel (Department of F i s h e r i e s designation 3B) of the Chehalis R i v e r , B r i t i s h Columbia on March 21, and were placed i n the experimental aquaria on March 23, 196?. Experimental Aquaria and Design Sixteen a q u a r i a , modified from a type p r e v i o u s l y employed by R. Bams of the F i s h e r i e s Research Board of Canada (pers. comm., 1966) were constructed by C a l v e r t Woodworks L t d . , Vancouver, B. C. Each aquarium measured 21}.—3/U- inches h i g h , 26 inches wide, and 2 inches deep (back to f r o n t ) . The base and end p l a t e s were made of s o l i d oak and were s l o t t e d to receive the two panes of 3/8 i n c h p l e x i g l a s s . P l e x i g l a s s has the advantages of high t e n s i l e s t r e n g t h and h i g h i n f r a r e d l i g h t transmittance (approx. 90%) and therefore was used i n place of g l a s s . I t s p r i n c i p a l disadvantage was i t s s u s c e p t i b i l i t y to s c r a t c h i n g . The area of ob s e r v a t i o n , viewed from the f r o n t , measured 22 inches by 23 inches * A p l a s t i c i n l e t p i p e , 1/2 i n c h i n diameter, was lo c a t e d ten inches from the bottom on the r i g h t -17-side and a 3A- inch p l a s t i c pipe served as the outlet on the l e f t side of each aquarium, one inch from the top. The gravel was retained between two 20 x 20 mesh stainless s t e e l screens, located i n s l o t s i n each end p l a t e . This permitted an open water area at the end of each aquarium to improve c i r c u l a t i o n . The amount of water entering each tank was c o n t r o l l e d with a Nalgene spigot valve on each i n l e t . The design of the aquarium i s shown schematically i n P i g . 6. The tanks were set on dexion framed plywood shelves, connected i n two series and designated i n the manner shown in Pi g . 7. The water was dechlorinated and a l l piping was polyethylene. P l a s t i c f i t t i n g s were used throughout, 1/2 inch for the i n l e t , and 3/lj. inch f o r the outlet p i p i n g . PVG ( p l a s t i c ) diaphragm valves, one on each i n l e t l i n e , provided gross flow control f o r each bank of aquaria. As i n the f i e l d study, gravel s i z e , b u r i a l depth, and egg density were each tested at two l e v e l s . The egg densities were 50 or 100 eggs per aquarium. The b u r i a l depths were again 8 inches and 12 inches. Large and small gravel sizes were l-l/l}. to 2-1/2 inches and 3A- to 1-l/ij. inches, r e s p e c t i v e l y . Eighteen inches of gravel were placed i n each aquarium on March 18 and the eggs deposited through PVG pipes on March 23, 1967. The pipes were removed a f t e r deposition and t h i s technique usually allowed the l o c a l i z a t i o n of the eggs in a single small pocket against the front plate of p l e x i g l a s s . The tanks were lig h t e d from 16 inches above the gravel surface by banks of 1+0 watt "cool white" fluorescent tubes 1. Inlet pipe of 1/2 inch polyethylene pipe. 2 . P last ic insert f i t t i ngs in in let and outlet l i nes . 3. Nalgene inlet valve. 4. Oak end f rame , pa in ted w i th Rustoleum enamel . 5. Oak b a s e , pa in ted with Rustoleum enamel . 6. Walls of 3 / 8 inch p l e x i g l a s s , inserted into grooves in ends and base and secured with S i l a s t i c adhesive. 7. S ta in less steel and s c r e e n s , 2 0 x 2 0 mesh. 8 . Outlet hose of 3 / 4 inch polyethylene pipe. L I G H T L I G H T L I G H T L I G H T LT I LT 2 LT 3 LT4 RT I RT2 RT3 RT4 100 50 100 50 8' 12" REPLICATE I 100 50 100 50 8' 12' REPLICATE 2 SMALL GRAVEL L I G H T L I G H T L I G H T L I G H T J L LB I LB 2 LB3 LB4 RBI RB2 RB3 RB4 100 50 100 50 100 50 100 50 8' 12' 8' 12" REPLICATE I REPLICATE 2 LARGE GRAVEL U re-connected to an Intermatic time switch kept adjusted to the natural day-night rhythm throughout the course of the experiment. Light was la r g e l y prevented from s t r i k i n g the front or back of the aquaria by means of black polyethylene c u r t a i n s . Some l i g h t may have been able to reach alevins against the glass because of the l i g h t transmittant properties of the p l e x i g l a s s . At any rate, the l i g h t conditions were as close to natural as possibl e . The entire area was surrounded by walls of black polyethylene to provide complete darkness when the l i g h t s were o f f , as well as to minimize other extraneous s t i m u l i . Observations ( i ) daytime Daytime observations were begun as soon as hatching started. With a few exceptions these observations were made every day from A p r i l llj. to May 18, and every second day from May 18 to June 10 i n the large gravel (May 18 to July 10 i n the small g r a v e l ) . The p o s i t i o n and orientation of each f i s h was recorded by placing a g r i d over the aquarium and copying on to a piece of paper ruled out i n the same fashion. L i f t i n g the black p l a s t i c curtain allowed enough l i g h t to carry out t h i s operation. ( i i ) night time Night observations were made with an infra-red viewer (AN/SAR-I4.). The in f r a - r e d l i g h t source consisted of two six vo l t lamps covered by Kodak Wratten f i l t e r s #87 and operated from the power mains by means of a transformer. Resolution was -21-not a b s o l u t e , and i t was o f t e n d i f f i c u l t to l o c a t e a l l of the f i s h known to be i n the g r a v e l . For t h i s reason, the r e s u l t s of the night time observations are of a more s u b j e c t i v e nature than are t h e i r daytime c o u n t e r p a r t s . Night observations were made on A p r i l 18, A p r i l 29, May l l i , May 19, May 29, May 30, June 1, and J u l y 9. In a d d i t i o n a s e r i e s of col o u r photographs was taken at one hour i n t e r v a l s from 2000 hours on June 7 to 0900 hours on June 8. An e l e c t r o n i c f l a s h o u t f i t was used. A n a l y s i s of Results Appendices g i v i n g d a i l y t a b u l a t i o n of a l l the l a b o r a t o r y data are a v a i l a b l e . Copies are on f i l e w i t h the Department of F i s h e r i e s , Resource Development Branch i n Vancouver; Dr. T. G. Northcote at the U n i v e r s i t y of B r i t i s h Columbia; and the author. ( i ) movement i n the g r a v e l Both the mean l a t e r a l and the mean v e r t i c a l p o s i t i o n s of the a l e v i n s i n the g r a v e l bed were determined f o r each observation date. This was done by a s s i g n i n g a number to each g r i d s e c t i o n , m u l t i p l y i n g t h i s number by the number of f i s h i n the s e c t i o n , summing over a l l s e c t i o n s , and d i v i d i n g t h i s value by the t o t a l number of f i s h v i s i b l e . The mean l a t e r a l and v e r t i c a l p o s i t i o n s were then p l o t t e d against time f o r each treatment, and d i f f e r e n c e s between the treatments analyzed. The amount of downward movement i n the large g r a v e l treatments was expressed as a percentage of the distance from - 2 2 -the point of b u r i a l to the bottom of the tank. In the small g r a v e l treatments, the f i g u r e used was a percentage of the distance from the f i r s t point of the graph to the bottom o f the tank. This m o d i f i c a t i o n was necessary because the eggs were not as l o c a l i z e d i n the small as i n the large g r a v e l . The amount of upward movement was c a l c u l a t e d as a percentage of the distance from the lowest point reached to the surface of the g r a v e l . The. parameters chosen to study l a t e r a l movement were extent of movement to the l e f t and extent of movement to the r i g h t , without any c o n s i d e r a t i o n o f the time at which these occurred. A l l of the above data were analyzed by means of the Yates t a b u l a r method of f a c t o r i a l a n a l y s i s . R e p l i c a t e s of four treatments were l o s t and no attempt was made to estimate them. I f both o f the r e p l i c a t e s of a treatment were a v a i l a b l e , they were averaged to provide the data used i n the a n a l y s i s . ( i i ) o r i e n t a t i o n i n the g r a v e l A l l of the f i s h e n t i r e l y v i s i b l e on the f r o n t p l a t e were recorded as being o r i e n t a t e d e i t h e r l e f t ( L ) , r i g h t (R), up (U), o r down (D). These d i r e c t i o n s were considered as the f o l l o w i n g angles (o(), clockwise from top c e n t r e : L=90, D=l80, R=270, U=360« A n a l y s i s was c a r r i e d out using the method o f Batschelet (1965) to determine the v e c t o r r e s u l t a n t (*£) f o r the e m p i r i c a l c i r c u l a r d i s t r i b u t i o n . This i s determined by the f o l l o w i n g set of equations: - 2 3 -x = i(coso(^ + coso^ + ...cosO^) = i S cosoc^ y = i(sinc< + sintxL + . ..sinc< ) = I t * sincX n 1 2 n n ±=x i r =yx 2 + y2 cos$. = x/r sinvl= y / r i s then determined from t a b l e s . A si m i l a r method was used by Groot (1965) to study the orientation of young sockeye salmon i n Babine Lake. The mean angle of orientation i n the 16 tanks was then compared over the following periods: f i r s t hatch - A p r i l 30, May 1-May 10, May 11-May 20, May 21-May 31, and June 1-June 10 (June 1-July 10 i n the small g r a v e l ) . Where possible, the data were summed over two r e p l i c a t e s as above. The data were also summed over the entire period of observation, and analyzed using the Yates tabular method. ( i i i ) s p a t i a l d i s t r i b u t i o n i n the gravel When three or more alevins were present i n the observation area t h e i r positions were connected by straight l i n e s , and the area contained within these l i n e s measured to the nearest vernier unit (v.u.) with an area planimeter. This was converted to square inches of gravel by multiplying the value by .01 sq. in ./v.u. x 16/l (the scale of the drawing). The value so obtained was then divided by the t o t a l number of a l e v i n s observed, to provide a measure of s p a t i a l d i s t r i b u t i o n , square inches per -21+-a l e v i n . This was done f o r each observation day f o r each aquarium, and the data were t a b u l a t e d . The only f i g u r e to be s t a t i s t i c a l l y analyzed was the maximum area u t i l i z e d p e r a l e v i n , using the Yates t a b u l a r method, as above. ( i v ) c o n d i t i o n a t emergence Pry were captured w i t h a dipnet i n the f o u r inches of open water above the g r a v e l s u r f a c e . Those emerging i n the small g r a v e l were captured immediately, but those emerging i n the large g r a v e l o f t e n could not be captured because o f the ease w i t h which they were able to r e - e n t e r the g r a v e l . Those f r y remaining i n the large g r a v e l a q u a r i a , a f t e r emergence was deemed complete, were counted out When the g r a v e l was removed (June 17-June 1 9 ) . A l l f r y were preserved i n 10% f o r m a l i n and a f t e r at l e a s t one week were measured to the nearest m i l l i m e t e r , d r i e d 2lj. hours i n a 37 C oven, and weighed to the nearest m i l l i g r a m on an e l e c t r i c balance. The data f o r both weight and l e n g t h were t a b u l a t e d and summed over the e n t i r e p e r i o d o f emergence. As w i t h the Robertson Creek d a t a , a c o n d i t i o n f a c t o r was then c a l c u l a t e d from the formula: v _ WEIGHT x 10 6 3 — LENGTH The data were then analyzed using the Yates t a b u l a r method. Two r e p l i c a t i o n s , when a v a i l a b l e , were averaged as above. (v) s u r v i v a l to emergence The percent s u r v i v a l was determined s o l e l y from the number of samples taken. At the end of the experiment, organic - 2 5 -remains i n the aquaria were examined but were u s u a l l y i n such an advanced s t a t e of decay as to be beyond enumeration. The f i g u r e f o r s u r v i v a l to emergence i s therefore a minimum one, since there i s a p o s s i b i l i t y that some f i s h may have been l o s t from the system, even though wire screens i n the tanks make t h i s h i g h l y u n l i k e l y . The f i g u r e s obtained were analyzed i n the usu a l manner to determine d i f f e r e n c e s a r i s i n g from treatments. ( v i ) p a t t e r n of emergence Due to the ease o f re-entry by the f r y i n t o the large g r a v e l , the date of f i r s t emergence i s the only r e l i a b l e parameter to compare emergence between treatments. The date of l a s t emergence was a r b i t r a r i l y set as June 10 i n the large g r a v e l and J u l y 10 i n t h e . s m a l l g r a v e l , and the date of maximum emergence was impossible to a s c e r t a i n i n the la r g e g r a v e l . The data f o r f i r s t emergence were analyzed f a c t o r i a l l y as bef o r e . P h y s i c a l F a c t o r s ( i ) water temperatures Temperatures were recorded at i n t e r v a l s ( u s u a l l y every second observation date) w i t h a hand thermometer i n the open water of each aquarium, A continuous temperature r e c o r d was als o obtained f o r one aquarium from May 9 t o J u l y 10 using a Taylor Automatic thermograph. The mean d a i l y temperature, c a l c u l a t e d as f o l l o w s , was p l o t t e d . m.d.t. = d a i l y maximum - d a i l y minimum -26-( i i ) oxygen concentrations Water samples were taken from the aquaria on June 16, four each from the two d i f f e r e n t gravel s i z e s . These samples were taken i n the screened area at the outlet end of the aquaria through a piece of s u r g i c a l rubber tubing. They were placed i n 300 ml BOD bottl e s and analyzed by the standard, unmodified Winkler method. Organic material was n e g l i g i b l e . ( i i i ) subgravel flow Five aquaria, three containing small gravel (1/3%, RT2, and RTi|.) and two containing large gravel ( L B I 4 . and RBI), were chosen to study t h i s environmental f a c t o r . The tests were conducted between June 13 and June 16. Approximately 1 ml of Rhodamine B dye was injected into the i n l e t pipe of each tank, above the i n l e t c ontrol valve, and i t s d i s t r i b u t i o n pattern i n the gravel was recorded at inter v a l s of two minutes to determine both rate of flow and flow c h a r a c t e r i s t i c s . -27-RESULTS FIELD STUDY Distance of Migration The Yates method of f a c t o r i a l analysis demonstrated that the only f a c t o r to affe c t s i g n i f i c a n t l y the distance of migration i n the Robertson Creek traps was gravel si z e , i . e . i n the larger gravel the alevins emerged f a r t h e r from the point of deposition. The mean values f o r distance of migration, summed over the entire emergence period, are shown i n Table I below. The variance (S^) i s shown i n brackets below each treatment mean. Condition at Emergence The analysis of variance revealed that there was no effe c t on condition at emergence of any o f the factors tested. Neither gravel si z e , b u r i a l depth, nor egg density s i g n i f i c a n t l y changed the value of the condition factor "k" (Table I I ) . The resu l t s may not be v a l i d , however, because of the r e l a t i v e l y small size of the samples. Survival to Emergence Apparent s u r v i v a l to emergence was extremely variable, ranging from 1 to 98% i n the small gravel, and 3 to 22% i n the large gravel. In t o t a l , 156 f r y were captured from the traps located i n the small gravel and i+9 from the traps located i n the large g r a v e l . - 2 8 -TABLE I . Mean D i s t a n c e ( F t . ) o f A l e v i n M i g r a t i o n f r o m P o i n t o f D e p o s i t i o n i n C o n c e n t r i c R i n g Traps a t Robertson Creek EGG DENSITY BURIAL DEPTH IN LARGE GRAVEL BURIAL DEPTH IN SMALL GRAVEL 8" 12" 8;" 12" 50 100 1.60 (.1123) 1.30 (.031*1) 1.14-7 (.0937) 1.58 (.14-055) 0.50 (.0569) 0.75 (.0000) 0.1+8 (.0970) 0.75 ( .0390) -29-TABLE I I . Condition Factor (k) f o r Fry Emerging within Concentric Ring Traps. See Text f o r Calculation of "k". EGG DENSITY BURIAL DEPTH IN LARGE GRAVEL BURIAL DEPTH IN SMALL GRAVEL 8 " 12" 8 " 12" So 100 1.29 1.1*8 1.1*2 1.37 1.1*0 0.96 1.1*3 1.1*1 - 3 0 -Besides these captures, 21 f r y were captured on the v-screen i n the small gravel channel between A p r i l 28 and May 16. During the same time period 191 fry were captured from the v-screen in the large gravel channel. The dye mark te s t s conducted May 5 indicated trapping e f f i c i e n c i e s of 71% and 3l±% from the v-screens i n these two channels respectively. Prom the following c a l c u l a t i o n s : x i n = 100 * 21 = 30 small 71 x = 100 f 191 = 5 6 2 large 34 i t would appear that 562 f r y vacated the concentric r i n g traps located i n the large gravel, while 30 f r y did the same i n the small g r a v e l . The revised t o t a l s for the estimates of s u r v i v a l therefore become: small gravel = l ^ 6 + 3 ° = 31% 600 large gravel = *f9 + 562 _ 1 0 2 % 600 The percent s u r v i v a l i n the large gravel i s c l e a r l y an overestimate. The reason f o r t h i s i s not c l e a r , since the weights and lengths of the dyed f r y captured on the v-sereen were less than the weights and lengths of the fry captured i n the concentric ring traps of the same channel (Table I I I ) . The y . . . . . . . e f f e c t of the dye on c a t c h a b i l i t y i s unknown, however. It appears obvious, however, that survival was very much greater i n the large gravel than i n the small gravel. This i s substantiated by the fact that although ij.9 dead eggs and Ifl -31-TABLE I I I . A Comparison of the Weights and. Lengths of the Fry Produced in Channel 8 with Those of the Dyed F i s h Introduced to the Channel and Recaptured. CHANNEL 8 FRY CAPTURES CONCENTRIC RING TRAPS DYED FISH CAPTURED MEAN WEIGHT . 0 6 3 gra. . 0 6 0 gm. MEAN LENGTH 35 .2 mm. 314..0 mm. -32-dead alevins were found i n the excavated Vibert boxes i n the small gravel channel, only two of the boxes from the large gravel channel contained eggs ( t o t a l of 10). Many fry were s t i l l unaccounted f o r i n the small gravel. They presumably died within the gravel a f t e r leaving the Vibert boxes. Despite the low percentage of captures within the rings themselves, the conclusions drawn regarding degree of l a t e r a l movement are s t i l l f e l t to be v a l i d . This i s because mean distance changed very l i t t l e from day to day, i n d i c a t i n g that f r y were not moving from one r i n g to another. In the large gravel, many f r y may have missed the concentric rings althogether and the mean distance moved may be an underestimate. Pattern of Emergence The number of days a f t e r planting when the f i r s t f r y appeared i n the traps i s l i s t e d in Table IV below. The analysis revealed that time to f i r s t emergence was s i g n i f i c a n t l y increased independently by both high density and small gravel; the l a t t e r i s the most important of the two f a c t o r s . It i s possible that the significance may be spurious, however, since emergence began very much l a t e r i n one treatment (91.0 days) than i n the others (mean of 77.9 days). The number of days a f t e r planting at which emergence was deemed complete was determined by the date at which the l a s t f r y l e f t the trap. These values are summarized in Table V below. The analysis of variance indicates that the 8 inch b u r i a l depth s i g n i f i c a n t l y decreased and the small gravel size s i g n i f i c a n t l y increased the time to l a s t emergence. - 3 3 -The length of the emergence p e r i o d (Table V value minus Table IV value) i s shown i n Table VI below. The data i s unworkable, however, because of the zero value i n the t a b l e . Excluding t h i s value and summing over a l l of the treatments i n each channel gives the f o l l o w i n g data f o r the mean leng t h of the emergence p e r i o d . large g r a v e l - 10.25 days sm a l l g r a v e l - 11.50 days A t - t e s t (Steele and T o r r i e , I960) shows that these are not s i g n i f i c a n t l y d i f f e r e n t at the .05 l e v e l . S i m i l a r t e s t s were c a r r i e d out f o r e f f e c t s of p l a n t i n g depth (8 inches = 9.50 days; 12 inches = 11.714- days) and p l a n t i n g d e n s i t y (50 eggs = 10.75 days; 100 eggs = 10.83. days). These t e s t s i n d i c a t e d that egg d e n s i t y had no e f f e c t on the len g t h of the emergence p e r i o d , but that i n c r e a s i n g the depth of p l a n t i n g s i g n i f i c a n t l y increased the l e n g t h of the emergence p e r i o d (at the .05 l e v e l ) . In toto the a n a l y s i s revealed that the f r y both began and completed t h e i r emergence e a r l i e r i n the l a r g e g r a v e l , but that the time taken to complete emergence was not s i g n i f i c a n t l y s h o r t e r than i n the smaller g r a v e l . There was evidence that the emergence p e r i o d was lengthened by an increased i n p l a n t i n g depth. The a l e v i n s buried at 8 inches began t h e i r emergence from the g r a v e l at the same time as t h e i r more deeply b u r i e d counterparts, but the former completed t h e i r emergence e a r l i e r . P l a n t i n g d e n s i t y had no e f f e c t on the p a t t e r n of emergence. -3k-TABLE IV. Number of Days a f t e r Planting at which the F i r s t Fry Appeared i n the Concentric Ring Traps. EGG DENSITY BURIAL DEPTH IN LARGE GRAVEL BURIAL DEPTH IN SMALL GRAVEL 8" 12" 8" 12" 50 100 77.0 74.5 78.0 79.0 79.0 91.0 79.5 78.5 TABLE V. Number of Days a f t e r Planting at which the Last Fry Disappeared from the Concentric Ring Traps. EGG DENSITY BURIAL DEPTH IN LARGE GRAVEL. BURIAL DEPTH IN SMALL GRAVEL 8" 12" 8" 12" 50 100 86.0 81*.5 89.0 90.0 88.5 91.0 93.0 90.0 - 3 5 -TABLE V I . Length o f the Emergence P e r i o d (Days) i n the C o n c e n t r i c R i n g T r a p s . EGG BURIAL LARGE DEPTH IN GRAVEL. BURIAL DEPTH IN SMALL GRAVEL. DENSITY 8 " 12" 8 " 12" 50 9.0 11.0 9.5 13.5 100 10.0 11.0 0 11.5 - 3 6 -P h y s i e a l F a c t o r s ( i ) oxygen concentrations Of the 8 samples taken from the standpipes on A p r i l 27, three were discarded because of excess organic matter. Of the remaining f i v e , three were from channel 7 (small g r a v e l ) and two from channel 8 (large g r a v e l ) . Mean values of m i l l i g r a m s of oxygen per l i t e r were: small g r a v e l - 19.7 mg O 2 / I . large g r a v e l - 12.1 mg 0^/1• The value f o r the small g r a v e l i s undoubtedly too h i g h but both s i t u a t i o n s were saturated o r supersaturated a t 1*8.1+ F. Those samples taken on June 11 gave the f o l l o w i n g values f o r the two channels: s m a l l g r a v e l - I3.6 mg O 2 / I . large g r a v e l - 11.1 mg 0 ^ / 1 , Again su p e r s a t u r a t i o n i s i n d i c a t e d . I t i s c l e a r that oxygen concentrations i n both channels were not l i m i t i n g f a c t o r s i n the environment. There i s also evidence that the small g r a v e l contained more oxygen than the large g r a v e l , but t h i s may be only an a r t i f a c t of sampling. The standpipes were b u r i e d s l i g h t l y deeper i n the large g r a v e l (x = 8.5 inches) than i n the small g r a v e l (x = 7.2 inches) because the shallower ones i n the large g r a v e l had to be r e j e c t e d due to the l a r g e r amounts of organic matter i n the samples. - 3 7 -( i i ) water temperatures The temperatures recorded i n the eigh t standpipes on A p r i l 27 were a l l i d e n t i c a l (I4.8.I4. F ) . Therefore, only one l o c a t i o n was subsequently used f o r temperature r e c o r d i n g , a standpipe i n channel 8 . The temperature was taken manually at each o b s e r v a t i o n time between May 6 and June 2, the p e r i o d of peak emergence. The mean d a i l y temperatures are graphed i n F i g . 8 . LABORATORY STUDY Of the s i x t e e n tanks i n the l a b o r a t o r y , only twelve gave u s e f u l d a t a . The eggs i n LT 1 died because of a water system f a i l u r e , while those i n LB 1 apparently died because of l a c k o f oxygen. Tanks LT 2 and RT 3 were of no use f o r most of the parameters s t u d i e d (with the exception of s u r v i v a l and emergence pattern) since the eggs were i n a d v e r t a n t l y b u r i e d i n the middle of the tank and few a l e v i n s could be seen aga i n s t the f r o n t p l a t e . Due to the large amount o f l o s t data, the treatments were considered to have had only one r e p l i c a t i o n , and the two r e p l i c a t e s were simply averaged i f both were complete. Behaviour of A l e v i n s i n the Experimental Aquaria W i t h i n a day of ha t c h i n g , the a l e v i n s moved downward ( F i g . 9a). This downward phase was more marked i n the large than i n the small g r a v e l due to the d i f f e r e n c e i n ease o f FIGURE 8, Mean Daily Water Temperatures-Robertson Creek - May+June,l967 o 5 5 -i C O I -39-on the t a n k bottom, 5 days a f t e r h a t c h i n g (x 7/16). 9c. A l e v i n s d i s p e r s i n g a l o n g the t a n k bottom, 31 days a f t e r h a t c h i n g (x 1/3). F i g u r e 9 . Phases i n the b e h a v i o u r o f the a l e v i n s i n the l a r g e g r a v e l . 9d. Fry near emergence, I4.I days a f t e r hatching (x 2 / 3 ) . 9e. Newly emerged f r y , 36 days a f t e r hatching (x 1/2). Figure 9 (cont.). Phases i n the behaviour of the alevins i n the large g r a v e l . -1*1-movement through the two m a t e r i a l s . In the larg e g r a v e l the a l e v i n s aggregated on the bottom o f the tank ( P i g . 9 b ) , but tended to more evident d i s p e r s a l i n the smaller g r a v e l ( F i g . 1 0 a ) . In both s i t u a t i o n s the a l e v i n s demonstrated what could be termed "explosive behaviour" when c l o s e l y grouped. This was c h a r a c t e r i z e d by the r a p i d s c a t t e r i n g of a group of a l e v i n s when one member of the aggregation moved. The group of a l e v i n s would subsequently reform. S i m i l a r behaviour was noted among sockeye salmon a l e v i n s by R. Bams (pers. comm., 1 9 6 6 ) , who suggested t h a t i t may be caused by carbon di o x i d e concentrations reaching a t h r e s h o l d l e v e l . As t h e i r y o l k sacs were absorbed, the a l e v i n s on the bottom o f the experimental aquaria c o n t a i n i n g the larg e g r a v e l spread out h o r i z o n t a l l y to the extreme r i g h t and l e f t sides ( P i g . 9 c ) . Prom there they made short f o r a y s i n t o the upper regions of the g r a v e l ( F i g . 9d) and f i n a l l y emerged ( F i g . 9 e ) . This p e r i o d w i l l be c a l l e d the upward phase. The snooperscope st u d i e s revealed t h a t the a l e v i n s (or, more c o r r e c t l y now, f r y ) were more dispersed through the gr a v e l during the n i g h t . However, much d i s p e r s i o n and movement was noted during the day time hours as w e l l . That the f r y were able to move extremely e a s i l y through the g r a v e l was evidenced by observations on May 3 1 , June 3 , and June 5 of f r y moving from the bottom o f the tank to the top, a t o t a l distance of about 36 inches, i n a time of about two minutes. Most f r y a f t e r emergence, however, d i d not appear to r e t u r n to any great depth i n the g r a v e l . Fry swimming i n the open water of the tanks would r e t u r n t o about -1*2-10a. Alevins beginning to disperse, 1 day a f t e r hatching (x 7/16). 10b. Alevin near the tank bottom, 1+2 days a f t e r hatching (x 2/3). Figure 10. Phases in the behaviour of the alevins i n the small gravel. -1*3-Figure 10 ( c o n t . ) . Phases i n the behaviour of the a l e v i n s i n the small g r a v e l . -kk-the f i r s t f o u r inches of the g r a v e l i f f r i g h t e n e d by a sudden movement. These f r y were never seen to r e t u r n to the bottom of the aquaria . The downward phase was much l e s s pronounced i n the small g r a v e l . In only two instances (RT 2 and RT d i d a l e v i n s reach the bottom of the tank ( P i g . 1 0 b ) . In most instances downward movement was s l i g h t , and was a s s o c i a t e d w i t h d i s p e r s i o n i n a l l d i r e c t i o n s from the point where hatching occurred ( P i g . 1 0 c ) . Most o f the a l e v i n s moved upward and out towards the side o f the aq u a r i a , although some moved s t r a i g h t up ( P i g . 1 1 ) . This p a t t e r n , i f r o t a t e d through 180 degrees ( i . e . three dimensional) would give the form of a rough cone, w i t h the apex s l i g h t l y below the point of h a t c h i n g . There appeared to be considerable day time emergence i n the sm a l l g r a v e l . This was r e l a t i v e l y c l e a r since the f r y were unable to re-enter the t i g h t l y packed g r a v e l a f t e r emergence. The tanks were oft e n c l e a r e d twice a day and many f r y were captured i n the afternoon, i n d i c a t i n g emergence since the morning sampling. The ho u r l y photographs taken on June 7 -June 8 ( P i g . 11) showed a slow but continuous movement through-out the n i g h t , w i t h most of the f r y emerging about O63O hours, about the time that the l i g h t s came on. The behaviour d i f f e r e n c e s noted above were a l l between the two g r a v e l s i z e s . No obvious d i f f e r e n c e s were noted between the l e v e l s of the other two f a c t o r s , b u r i a l depth and egg d e n s i t y . -K5-Figure 11. Nocturnal movement of coho salmon alevins (53 days a f t e r hatching) i n the small gravel of the experimental aquaria. Upper: 2100 hours ( l i g h t s o f f at 2030 hours); Lower: 2i*00 hours (x l/k) • -lj.6-Degree of V e r t i c a l Movement The alevins exhibited s i g n i f i c a n t l y greater movement during the downward phase in the large gravel than i n the small gravel (Table V I I). The mean v e r t i c a l positions are plotted for each available replicate of each treatment i n P i g . 12. The analysis also revealed that the alevins i n the small gravel moved downward to a s i g n i f i c a n t l y greater degree when planted at lower density. The analysis of variance showed that large gravel, 8 inch b u r i a l depth, and egg density of 50 a l l acted to increase the extent of movement i n the upward phase (Table V I I I ) . The analysis i s not p a r t i c u l a r l y revealing, however, since i t i s biased by the fact that some alevins were undoubtedly trapped within the small gravel, and that they were located deeper i n the gravel when the eggs were planted at the deeper l o c a t i o n . Degree of La t e r a l Movement It i s apparent (Pig. 13) that the predominant l a t e r a l movement was towards the i n l e t i n the upward phase of the migration, even though movement began towards the outlet during the downward phase (most evident i n the large g r a v e l ) . Movement towards the outlet was s i g n i f i c a n t l y greater i n the larger than i n the smaller gravel (Table IX). The degree of t h i s movement was also greater at the higher density and at the deeper b u r i a l depth, although these e f f e c t s were not as great as that of the larger gravel. -14.7-TABLE VII. Percent of Possible Downward Movement in the Experimental Aquaria. EGG DENSITY BURIAL DEPTH IN LARGE GRAVEL BURIAL DEPTH IN SMALL GRAVEL 8" 12" 8" 12" 100 100.0 100.0 100.0 100.0 37.0 19.0 28.1 17.7 i - 8 -~I Inches From A q u o r i u m F l o o r F r o m A q u a r i u m F l o o r ? . T • 8-Jfi-C z m 8 o r > w m - 5 0 -TABLE VIII. Percent of Possible Upward Movement in the Experimental Aquaria. EGG-DENSITY BURIAL DEPTH IN LARGE GRAVEL BURIAL DEPTH IN SMALL GRAVEL 8" 12" 8" 12" 50 100 90.0 69.0 61]..0 83.0 80.0 63.0 6I4..O 1+7.0 s ° a. = 1 .1 8 I N C H E S SO E G G S 2 0 C E N T R E OF T A N K o\ J 1 1 L_ ! 5 10 IS 20 25 301 10 is~~ - I 1 L 20 25 30 J l _ ~K> is" 20 25 30 6 I N C H E S 1 0 0 E G G S C E N T R E O F T A N K i • '. —I 1 U l i | 5 10 15 20 25 301 S. 10 15 20 2 5 i o T T J U J 1 I 5 C 15 20 25 30 12 I N C H E S 5 0 E G G S 12 I N C H E S 100 E G G S C E N T R E OF T A N K -1 1 1 l_ J » 1 0 1 5 20 25 301 5 i 1 1 I L U _ 10 15 20 25 STT ~s i£ is" 2 0 2 5 3 0 1-4 C E N T R E O F T A N K — -J 1 1 1 I 5 10 IS 20 25 » l 5 10 15 20 25 30| 10. 15 20 J U N E 2 5 J O FIGURE 13-1 £f\i , ? r o «i M!r2!?. 0Vne A L M i n S J n t h e ' Q r g e 9 r Q V e l - U p p e r " 8 i n c h b u r i a l ^ P t h , lower-12 inch burial depth. Letr side - egg density 50, right side egg density 100. 1 ' Ditptocermnt From C*ntr» Dilelocament From C o n l r t - 5 3 -The a n a l y s i s o f the data shown i n Table IX showed that large g r a v e l and low density s i g n i f i c a n t l y i ncreased the extent of movement towards the i n l e t . The t o t a l range o f movement i s obtained by adding the f i g u r e s i n Tables IX and X, and i s summarized i n Table X I . Both large g r a v e l and low de n s i t y s i g n i f i c a n t l y increased the degree of l a t e r a l movement. Since these r e s u l t s agree most c l o s e l y w i t h those of the a n a l y s i s of movement to the i n l e t , i t i s c l e a r that movement towards the i n l e t was the primary component of l a t e r a l movement and was more important than the movement to the o u t l e t which accompanied the downward movement immediately a f t e r h a t c h i n g . O r i e n t a t i o n i n the Gravel The most common d i r e c t i o n of o r i e n t a t i o n $ ) l a y between 270 and 3bO degrees, i . e . upwards and towards the i n l e t (Table X I I ) . This agrees w e l l w i t h the data on mean v e r t i c a l and l a t e r a l p o s i t i o n s presented above. Downward o r i e n t a t i o n was noted i n on l y a few i n s t a n c e s , a l l i n the small g r a v e l . The f a c t t h a t i t was absent i n the larg e g r a v e l , where downward movement was most evident, i s i n d i c a t i v e e i t h e r of a non-orientated mechanical " s l i p p i n g through" to the bottom of the tanks, o r of a r a p i d o r i e n t a t e d movement towards the bottom. Since the a l e v i n s i n the large g r a v e l appeared on the bottoms very soon a f t e r h a t c h i n g , i t i s d i f f i c u l t to determine which of these p o s s i b i l i t i e s i s c o r r e c t . No c o n s i s t e n t d i f f e r e n c e appears to e x i s t between the l e v e l s of the other f a c t o r s examined, i . e . b u r i a l depth and egg d e n s i t y . -51*-TABLE IX. Extent of L a t e r a l Movement to the Out l e t (Expressed as Inches from Center) i n the Experimental A q u a r i a . EGG DENSITY BURIAL DEPTH IN LARGE GRAVEL BURIAL DEPTH IN SMALL GRAVEL 8" 12" 8" 12" 50 100 6.3 5.5 6.2 7.8 0.2 2.5 1.5 1.8 TABLE X. Extent of L a t e r a l Movement to the I n l e t (Expressed as Inches from Center) i n the Experimental A q u a r i a . EGG BURIAL LARGE DEPTH IN GRAVEL BURIAL SMALL DEPTH IN GRAVEL DENSITY 8" 12" 8" 12" 50 8.2 8.3 6.2 k .7 100 2.9 5.1 3.8 2.8 -55-TABLE XI. T o t a l L a t e r a l Movement (Expressed as Inches from Center) i n the Experimental A q u a r i a . EGG DENSITY BURIAL DEPTH IN LARGE GRAVEL. BURIAL DEPTH IN SMALL GRAVEL 8 " • 12" 8 " 12" 50 100 114-.5 8.1* l i * . 5 12 .9 6.1* 6 .3 6 . 2 l*.6 - 5 6 -TABLE X I I . Mean O r i e n t a t i o n D i r e c t i o n by Time P e r i o d , f o r Each Treatment i n the Experimental A q u a r i a . D i r e c t i o n s are Expressed as Angles, Counterclockwise from Top Center. DATE TREATMENT HATCH-, A p r i l 30 May 1 -May 10 May 11-May 20 May 21-May 31 June 1-END DEGREES DEGREES DEGREES DEGREES DEGREES -o o H 135 338 351 213 270 e CM H O u\ 214 284 328 342 354 o o H i+6 360 347 343 358 CO O 337 333 343 345 356 GRAVEL CM H O O H 352 27 323 347 357 GRAVEL O 360 88 315 330 334 GRAVEL GRAVEL •3 « CO O O H 270 90 50 303 352 3 O "LA 5 8 272 277 342 -57-The orientation data were summarized by t o t a l l i n g over the entire period in which alevins or f r y were observed i n the gravel (Table XIII). The analysis of variance revealed that the angle of orientation was not s i g n i f i c a n t l y affected by gravel s i z e , b u r i a l depth, or egg density at the .05 l e v e l . S p a t i a l D i s t r i b u t i o n i n the Gravel The area occupied by each a l e v i n increases with time (Pig. llj.). The large fluctuations are caused by the emergence from the gravel of those alevins nearest the surface, resulting in a decrease i n the area covered by those s t i l l remaining in the gravel. I f these fluctuations are ignored the graphs suggest exponential curves, and are a l l s i m i l a r except that they cover a greater area i n the large gravel treatments. In other words, the alevins were more dispersed i n the large gravel. This i s also shown by the analysis of variance of the data shown in Table XIV, which showed that dispersion was s i g n i f i c a n t l y increased by large gravel s i z e . Other factors had no s i g n i f i c a n t e f f e c t . It i s s i g n i f i c a n t that the mean area occupied per a l e v i n was not affected by the number of alevins present, i . e . irregardless of number each alevin occupied the same gravel area. This indicates that the f i s h were spacing themselves out within the gravel and that competition may have been occurring. Condition at Emergence Pry emerging from the small gravel were i n s i g n i f i c a n t l y better condition than those emerging from the large gravel - 5 3 -TABLE X I I I . Mean Angle of O r i e n t a t i o n i n the G r a v e l , Expressed as Degrees, Counterclockwise from Top Center. EGG DENSITY BURIAL DEPTH IN LARGE GRAVEL BURIAL DEPTH IN SMALL GRAVEL 8" 12" 8" 12" 50 100 325 330 314-9 33 3*4-8 357 339 310 - 5 9 -ioor FIGURE 14.-I Graph of the area occupied by the alevins in the large gravel. Upper - 8 inch burial depth, lower - 12 inch burial depth. Left side - egg density 50, right side—egg density 100. FIGURE 14.-2 Graph of the area occupied by the alevins in the small gravel. Upper- 8 inch burial depth, lower - 12 inch burial depth. -61-TABLE XIV. The Maximum Area U t i l i z e d Per A l e v i n i n the Experimental A q u a r i a . Expressed as Square Inches Per A l e v i n V i s i b l e . EGG DENSITY BURIAL DEPTH IN LARGE GRAVEL BURIAL. DEPTH IN SMALL GRAVEL 8" 12" 8" 12" 50 100 28 .06 30.79 27 .38 28.1*3 8.64 6.40 11.14 3.23 -62-(Table XV). B u r i a l depth and egg density had no effect on the condition index of the emerging f r y . Survival to Emergence Survival (expressed as a percentage of emergent f r y i n r e l a t i o n to the number of eggs deposited) i s summarized i n Table XVI. The analysis of variance showed that s u r v i v a l was s i g n i f i c a n t l y lower i n the smaller gravel. The difference may not be as marked as i t appears, however, since even a f t e r July 12 there were s t i l l many f r y i n the small gravel which may or may not have emerged at a l a t e r date. Pattern of Emergence The nature of the experimental aquaria allowed only analysis of the number of days to f i r s t emergence (Table XVII). Only b u r i a l depth s i g n i f i c a n t l y affected the time taken to f i r s t emergence, i . e . deeper b u r i a l depth resulted i n increased time . It i s obvious that the small gravel greatly lengthened the period of emergence, since some fry were s t i l l emerging up to July 10. I t i s suggested that future studies of t h i s type would do well to equip the aquaria with traps to capture any f r y immediately a f t e r emergence. The f a i l u r e to provide such f a c i l i t i e s made i t impossible to determine the pattern of emergence, p a r t i c u l a r l y i n the large gravel, which the f r y r e a d i l y re-entered. Further, time of emergence may be an important factor i n any consideration of subsequent s u r v i v a l . - 6 3 -TABLE XV. C o n d i t i o n I n d i c e s ( k) o f the F r y Emerging from the E x p e r i m e n t a l A q u a r i a . EGG DENSITY BURIAL DEPTH IN LARGE GRAVEL BURIAL DEPTH IN SMALL GRAVEL 8" 12" 8" 12" 50 100 1.55 1.67 1.37 1.1*7 1.72 1.71 1.89 1.93 -61*-TABLE XVI. P e r c e n t S u r v i v a l t o Emergence i n the E x p e r i m e n t a l A q u a r i a . EGG DENSITY BURIAL DEPTH I N LARGE GRAVEL BURIAL DEPTH I N SMALL GRAVEL 8" 12" 8" 12" 50 100 91* 52 92 86 1*6 76 1*5 30 - 6 5 -TABLE XVII. Number o f Days a f t e r P l a n t i n g t o F i r s t Emergence i n t h e E x p e r i m e n t a l A q u a r i a . EGG BURIAL DEPTH IN LARGE GRAVEL BURIAL SMALL DEPTH I N GRAVEL DENSITY 8" 12" 8" 12" 50 67 71 67 68 100 67 67 67 73 -66-Physical Factors ( i ) temperature The temperature varied l i t t l e from one aquarium to another, one degree F being the maximum variance encountered. The thermograph record, therefore, gives the approximate mean d a i l y temperatures f o r a l l of the aquaria ( F i g . 15). The mean d a i l y water temperature varied only l+.i* G (8 F) over a period of two and one h a l f months, and averaged approximately 5.6 C (10 F) less than i n the Robertson Creek channels. ( i i ) oxygen concentrations The mean oxygen concentrations of the water i n the two gravel sizes were found to be: small gravel - 12.3 nig 0^/1, large gravel - 12.1 mg 0^/1. Both s i t u a t i o n s , then, were well supplied with oxygen and t h i s environmental variable was not a l i m i t i n g one i n either of them. ( i i i ) subgravel flow The flow c h a r a c t e r i s t i c s observed i n the gravel are shown i n F i g . 16. In the small gravel, the flow was l i n e a r i n the middle of the tank, but tended to upwell at the edges. Flow through the large gravel was si m i l a r but more r a p i d . Flow rates through the gravel, calculated from the time required f o r the dye to traverse the aquaria, were approximately .08 and .20 feet per minute i n the small and large gravel respectively. These values are considerably less than the flow rates previously observed i n the Robertson Creek channel gravel. FIGURE 15. Mean Daily Temperatures Laboratory — April to July , 1967. A J 1 • / • / \ A / { / 1 v / V - 25 30 —APRIL 1 5 10 15 20 25 30 MAY 5 10 15 20 25 30 JUNE 5 10 15 20 25 JULY -68-SMALL GRAVEL 25 minutes to reach left side. LARGE GRAVEL 10 minutes to reach left side. Figure 16. Subgravel flow through the experimental aquaria. -69-DISCUSSION S e v e r a l c o n s i d e r a t i o n s must be borne i n mind throughout the d i s c u s s i o n of the above r e s u l t s . F i r s t , because of unavoidable c o m p l i c a t i o n s , d i f f e r e n t s p e c i e s of salmon were used i n the two phases o f the p r o j e c t . Coho salmon were used i n the l a b o r a t o r y and chum salmon i n the f i e l d . I t may not be l o g i c a l to assume t h a t the behaviour p a t t e r n s o f the two s p e c i e s are g o ing to be the same, because t h e i r l i f e h i s t o r i e s are q u i t e d i f f e r e n t a f t e r emergence from the g r a v e l . On the other hand, however, the work o f Roth and G e i g e r (1963) on Salmo t r u t t a ; Stuart (1953) on S. t r u t t a ; Woodhead (1957) on S. t r u t t a , S. i r i d e u s , and S. s a l a r ; and White (1915) on S a l v e l i n u s f o n t i n a l i s i n d i c a t e that a l l of these s p e c i e s s t u d i e d t o date have s i m i l a r behaviour i n the e a r l y s t a g e s . F u r t h e r , Campbell's unpublished study of coho and s t e e l h e a d a l e v i n s i n d i c a t e t h a t these s p e c i e s behave i n the same manner as the Loch t r o u t s t u d i e d by S t u a r t . Comparative s t u d i e s o f salmonid f r y have i n d i c a t e d , however, that although behaviour may show gross s i m i l a r i t i e s , d e t a i l e d o b s e r v a t i o n s r e v e a l a great many d i f f e r e n c e s between s p e c i e s . F u r t h e r s t u d i e s may show that t h i s i s true f o r the a l e v i n as w e l l . Secondly, i n the l a b o r a t o r y study, the assumption i s made th a t the behaviour o f the a l e v i n s along the g l a s s i s the same as those deeper i n the g r a v e l . T h i s may not be a v a l i d assumption, p a r t i c u l a r l y i n the s m a l l g r a v e l , where those a l e v i n s on the p l e x i g l a s s would be exposed t o much more l i g h t -70-than those deeper i n the g r a v e l . The a l e v i n s i n one aquarium however, were not v i s i b l e but showed s i m i l a r emergence p a t t e r n s , c o n d i t i o n at emergence, and s u r v i v a l to emergence to those a l e v i n s exposed to l i g h t , suggesting that the e f f e c t of the p l e x i g l a s s on behaviour was minimal. T h i r d l y , i t i s assumed that d i f f e r e n c e s i n temperature, oxygen and flow c o n d i t i o n s have not a f f e c t e d the r e s u l t s . Oxygen was never found to be i n short supply i n the la b o r a t o r y or the f i e l d . Therefore, flow r a t e s must have been adequate i n both s i t u a t i o n s , even though slower i n the smaller g r a v e l . Temperature c o n d i t i o n s were much lower i n the l a b o r a t o r y , but v a r i e d l i t t l e from tank to tank. The e f f e c t s of the three v a r i a b l e s t e s t e d are summarized i n Table XVIII and w i l l now be discussed i n t u r n . E f f e c t of Gravel Size In the l a r g e r g r a v e l the a l e v i n s moved f a r t h e r l a t e r a l l y (both towards the i n l e t and the o u t l e t ) , towards the bottom, and towards the s u r f a c e . They therefore covered a greater area of g r a v e l i n the l a b o r a t o r y . For the same reason the a l e v i n s emerged f a r t h e r from the p o i n t of d e p o s i t i o n i n the f i e l d . In the f i e l d , but not i n the l a b o r a t o r y they began t h e i r emergence e a r l i e r , and, i n both s i t u a t i o n s , completed i t e a r l i e r i n the large g r a v e l . S u r v i v a l was much hig h e r i n the large g r a v e l i n both s i t u a t i o n s , but the f r y were i n poorer c o n d i t i o n at emergence from the large g r a v e l , at l e a s t i n the l a b o r a t o r y . -71-TABLE X V I I I . The E f f e c t s o f I n c r e a s i n g G r a v e l S i z e , B u r i a l Depth and Egg D e n s i t y on the Parameters Measured i n the Study. +, I n c r e a s e * -, Decreas e ; 0, No E f f e c t ; N.E., Not Examined PATTERN OF EMERGENCE LENGTH N.E. N.E. o o PATTERN OF EMERGENCE F INAL "NT TP • • * • 525 I + o PATTERN OF EMERGENCE I N I T I A L o + O i o + SURVIVAL TO EMERGENCE + o O + o o CONDITION AT EMERGENCE. 1 o o o o o SPATIAL DISTRIBUTION + o o • N.E. N.E. ORIENTATION IN THE GRAVEL o o o • • 525 N.E. LATERAL MOVEMENT TOTAL + o 1 • • • 525 LATERAL MOVEMENT INLET + o 1 N.E. IN .Hi . N.E. LATERAL MOVEMENT OUTLET + + N.E. IN • Sit t N.E. VERTICAL MOVEMENT DOWN + o • • • 525 TJ F IN . £J . N.E. VERTICAL MOVEMENT UP + 1 1 N.E. • 525 N.E. DISTANCE OF .MIGRATION t • 525 N.E. N.E. O o EFFECTS OF INCREASING GRAVEL SIZE INCREASING BURIAL DEPTH INCREASING BURIAL DENSITY INCREASING GRAVEL SIZE INCREASING BURIAL DEPTH • — — INCREASING BURIAL DENSITY EFFECTS OF LABORATORY . . STUDY FIELD STUDY - 7 2 -The g r e a t e r movement, e a r l i e r emergence and b e t t e r s u r v i v a l were probably the r e s u l t of more freedom of movement through the l a r g e r g r a v e l . The poorer c o n d i t i o n at emergence i n the l a b o r a t o r y may have been the r e s u l t of more frequent a c t i v i t y i n the large g r a v e l , where there was l e s s support f o r the a l e v i n s w i t h t h e i r l a r g e y o l k sacs. The a l e v i n s , c o n s t a n t l y having to r i g h t themselves, may u t i l i z e more energy f o r maintenance and thus be s m a l l e r at emergence than t h e i r counterparts i n the s m a l l e r g r a v e l . Such a r e l a t i o n s h i p has been noted p r e v i o u s l y by both Marr ( 1 9 6 3 , 1965) and Bams (pers. comm., 1 9 6 6 ) . The l a t t e r i n v e s t i g a t o r suggests that the a l e v i n s i n the absence of support have a g r e a t e r tendency to aggregate, to support each other i n a sense. Such aggregation was indeed noted i n the present study during the p e r i o d when the a l e v i n s were on the bottom of the a q u a r i a , at which time they would have l i t t l e support from the g r a v e l . E f f e c t of B u r i a l Depth The time to f i r s t emergence ( i n the l a b o r a t o r y ) and to l a s t emergence ( i n the f i e l d ) was increased by burying the eggs at 12 i n c h e s . The net e f f e c t , t h e r e f o r e , was to increase the t o t a l l e n g t h of the emergence p e r i o d > as noted i n the f i e l d . This may have been simply because the a l e v i n s had a greater distance to move to the surface when bu r i e d at a greater depth, or because l e s s l i g h t was able to penetrate to that depth. In the l a b o r a t o r y , i n c r e a s i n g b u r i a l depth increased the amount of movement to the o u t l e t and decreased the amount of -73-upward movement. The reason f o r these r e s u l t s cannot p r e s e n t l y be a s c e r t a i n e d . B u r i a l depth had no e f f e c t on s u r v i v a l to emergence, c o n d i t i o n at emergence, or distance moved from the point of d e p o s i t i o n i n the f i e l d . Another f a c t o r i n any c o n s i d e r a t i o n of optimum b u r i a l depth should be p r e d a t i o n . The work of P h i l l i p s and C l a i r e (1966) i n d i c a t e d that the s c u l p i n , Cottus p e r p l e x u s t c o u l d be a. s i g n i f i c a n t predator on salmonid a l e v i n s , when the g r a v e l i s large enough to al l o w access to them. In one i n c h g r a v e l s c u l p i n s were able to penetrate approximately seven inches to consume a l e v i n s . Small s c u l p i n s (1.5 inches) were able to penetrate l i * inches i n t o the 1 inch g r a v e l . Obviously, g r a v e l s i z e and b u r i a l depth i n t e r a c t , and since b u r i a l depth has few i f any d e t r i m e n t a l e f f e c t s , and large g r a v e l many b e n e f i c i a l ones, i t would appear best to bury eggs at gr e a t e r depth i n l a r g e r g r a v e l , and not near the surface i n f i n e r m a t e r i a l . E f f e c t o f Egg Density High egg den s i t y decreased the degree of v e r t i c a l movement and of l a t e r a l movement, w i t h the exception o f movement towards the l e f t . There was also some evidence that f r y began t h e i r emergence e a r l i e r when present at the h i g h e r d e n s i t y . The area u t i l i z a t i o n on a per a l e v i n b a s i s was not a f f e c t e d by the b u r i a l d e n s i t y . This may be evidence of competition i n the g r a v e l e i t h e r f o r oxygen or f o r food ( D i l l , 1967) . On the other hand, the a l e v i n s may be spacing themselves -71*-out i n response to carbon dioxide or nitrogenous waste c o n c e n t r a t i o n s . Further work on t h i s subject would c e r t a i n l y appear warranted. Responses of the A l e v i n s to Light Roth and Geiger (1963) found that a l e v i n s o f brown tr o u t were i n i t i a l l y photonegative and moved downward a f t e r h a t c h i n g . A f t e r spending some time on the bottom of the cont a i n e r s they then became p o s i t i v e l y p h o t o t a c t i c , moved back towards the surface and emerged. That t h i s was not a response to g r a v i t y was determined by t u r n i n g the c y l i n d r i c a l c o n t a i n e r s sideways. The authors concluded that l i g h t was the s i n g l e most important f a c t o r i n a l l o w i n g a l e v i n s to f i n d t h e i r way up and out of the g r a v e l bed. Bams (pers. comm., 1967 ), on the other hand, found that l i g h t a c t u a l l y retarded emergence and that g r a v i t y was a more important f a c t o r i n subgravel o r i e n t a t i o n . The l a t t e r view seems a more r e a l i s t i c one, since i t has been demonstrated by Heard (1961*), as w e l l as by Roth and Geiger themselves, that l i g h t can penetrate only i n t o the upper few centimeters o f the g r a v e l . In the present experiment, the a l e v i n s i n the large g r a v e l , i . e . where l i g h t penetrated the f a r t h e s t , showed more downward movement and more a c t i v i t y at night than d i d the a l e v i n s i n the sma l l e r g r a v e l . The explanation f o r such behaviour comes from the s t u d i e s of Woodhead (1957), Stuart (1953) and White (1915) who found that newly hatched Salmo larvae were n e g a t i v e l y p h o t o t a c t i c . Stuart found that the a l e v i n s during the p e r i o d of -75-f i n a l y o l k absorption became e i t h e r p o s i t i v e l y p h o t o t a c t i c or n e u t r a l to l i g h t . L i g h t may not be of any importance i n nature u n t i l the a l e v i n s have entered the upper few inches of g r a v e l . I t i s u n c e r t a i n , t h e r e f o r e , why the young larvae are n e g a t i v e l y p h o t o t a c t i c but i t may prevent them from premature emergence i f by chance they are b u r i e d too near the s u r f a c e , or reach there too e a r l y i n t h e i r upward m i g r a t i o n . The a l e v i n s ' response to l i g h t probably accounts f o r the large p r o p o r t i o n of d a y l i g h t emergence noted, p a r t i c u l a r l y i n the s m a l l e r g r a v e l , where the a l e v i n s (with the exception o f those against the g l a s s ) had no experience w i t h the day-night c y c l e u n t i l very near the s u r f a c e . Movement through the g r a v e l to the surface may be the r e s u l t of g r a v i t y o r i e n t a t i o n or the r e s u l t of i n t e r n a l p h y s i o l o g i c a l f a c t o r s , i . e . m o t i v a t i o n , Both of these need to be examined i n f u t u r e i n v e s t i g a t i o n s . Heard (1961*) a l s o suggests that daytime emergence may exceed daytime m i g r a t i o n downstream, s i n c e , once the f i s h have emerged i n t o high l i g h t i n t e n s i t i e s and f i l l e d t h e i r a i r bladders they seek cover u n t i l nighttime (Neave, 1955J Hartman et a l , 1962). In t u r b i d r i v e r s , m i g r a tions of pink and chum 3almon f r y have a l s o been recorded during d a y l i g h t hours (Neave, 1955). I t should be noted, however, that the species o f Oncorhynchus vary i n t h e i r response to l i g h t (Hoar, 1958). The s i g n i f i c a n c e of t h i s f i n d i n g to the present study i s u n c e r t a i n , although i t i n d i c a t e s that we should a v o i d i n f e r r i n g the -76-behaviour of an e n t i r e genus from stud i e s conducted on one or two s p e c i e s . A comparative study of a l e v i n behaviour should be c a r r i e d out. Responses of the A l e v i n s to Current White (1915) found that brook t r o u t a l e v i n s were p o s i t i v e l y r h e o t r o p i c (=rheotactic) at the time of h a t c h i n g , although both B i s h a i (I960) and Stuart (1953) found that brown tr o u t a l e v i n s were n e g a t i v e l y r h e o t r o p i c u n t i l y o l k a b s o r p t i o n , at which time t h e i r response became a p o s i t i v e one. Roth and Geiger (I963) found that brown tr o u t a l e v i n s were p o s i t i v e l y r h e o t a c t i c throughout the e n t i r e a l e v i n stage. The present experiments i n d i c a t e that coho salmon a l e v i n s are d e f i n i t e l y p o s i t i v e l y r h e o t a c t i c i n l a t e r stages, but show no c o n s i s t e n t o r i e n t a t i o n to current f o r the f i r s t few weeks a f t e r hatching, d i s t r i b u t i n g themselves i n a f a i r l y random manner w i t h respect to c u r r e n t . Optimal Conditions of P l a n t i n g The present experiments o f f e r c o n c l u s i v e evidence that large g r a v e l i s the p r e f e r r e d m a t e r i a l f o r a r t i f i c i a l i n c u b a t i o n and spawning channels, since i t r e s u l t s i n e a r l i e r emergence and b e t t e r s u r v i v a l r a t e s . Several f a c t o r s suggest, however, that the g r a v e l should be of a more mixed grade than that u t i l i z e d i n these experiments. These f a c t o r s i n c l u d e the poorer c o n d i t i o n at emergence, the p o s s i b i l i t y of higher predation i n the g r a v e l , and wider s p a t i a l d i s t r i b u t i o n . -77-i B u r i a l depth should be great enough to prevent predation but not so deep as to s e r i o u s l y r e t a r d emergence, since f r y which emerge over a short p e r i o d of time and at higher water l e v e l s probably s u f f e r l e s s p r e d a t i o n during t h e i r downstream m i g r a t i o n . F u r t h e r , e a r l y emerging f r y of such species as coho and chinook salmon stand a b e t t e r chance o f f i n d i n g s u i t a b l e h a b i t a t s i n the stream channel and subsequently have higher growth r a t e s (Mason and Chapman, 1965). B r i g g s (1953) found that coho b u r i e d t h e i r eggs at an average depth of 9.8 i n c h e s . Burner (1951) found that the average depths of chum and coho salmon eggs i n the Columbia Ri v e r were 8.5 and 8.0 inches r e s p e c t i v e l y , while Kusnetzov (1928) found chum salmon eggs to be b u r i e d 9 to 10 i n c h e s . This depth, i n view of the e f f e c t s of g r a v e l s i z e noted i n the present study, i s probably optimum. There i s no evidence that e i t h e r of the d e n s i t i e s u t i l i z e d i n t h i s study were high enough to make competition an important c o n s i d e r a t i o n . Egg pockets i n n a t u r a l redds, however, may c o n t a i n eggs at h i g h e r d e n s i t i e s than those studied here. The maximum density u t i l i z e d i n the l a b o r a t o r y was 150 eggs per cubic f o o t . This study, being one of the f i r s t conducted on the subgravel b e h a v i o u r a l ecology of the P a c i f i c salmon, may provide u s e f u l background informa t i o n f o r future i n v e s t i g a t o r s , suggest t e s t a b l e hypotheses f o r them, and stimulate them to concentrate at l e a s t some of t h e i r e f f o r t s on t h i s rewarding f i e l d of research. S e v e r a l f u t u r e s t u d i e s have been s u g g e s t e d by the p r e s e n t work. These i n c l u d e m o d i f i c a t i o n o f emergence t i m i n g t h r o u g h m a n i p u l a t i o n o f e n v i r o n m e n t a l c o n d i t i o n s , c o m p a r a t i v e e t h o l o g i c a l s t u d i e s o f the s a l m o n i d a l e v i n , p a r t i c u l a r l y i n response to l i g h t , and s t u d i e s of i n t e r a c t i o n o r c o m p e t i t i o n between a l e v i n s w i t h i n the g r a v e l b e d . Such s t u d i e s s h o u l d be co n d u c t e d i n the immediate f u t u r e , b o t h because o f t h e i r t h e o r e t i c a l and t h e i r p r a c t i c a l i m p l i c a t i o n s . -79-LITERATURE CITED Alderdice, D.P., Wickett, W.P., and J.R. Brett, 1958. Some ef f e c t s of temporary exposure to low dissolved oxygen l e v e l s on P a c i f i c salmon eggs. J . Pi s h . Res. Bd. Canada, 15(2): 229-249. Batschelet, E. 1965. S t a t i s t i c a l Methods for the Analysis of Problems i n Animal Orientation and ce r t a i n B i o l o g i c a l  Rhythms"! American I n s t i t . of B i o l o g i c a l Sciences, Washington. 57 PP. Bianchi, D.R. 1963. The ef f e c t s of sedimentation on egg sur v i v a l of rainbow trout and cutthroat t r o u t . MSc. Thesis, Montana State College, 28 pp. Bis h a i , H.M. i 9 6 0 . The ef f e c t of water currents on the survival and d i s t r i b u t i o n of f i s h larvae. J . Conseil 25(2) : 134.-1146. ' 1961a. The ef f e c t of s a l i n i t y on the survival and di s t r i b u t i o n of l a r v a l and young f i s h . Ibid 26(2):166-179. _ _ _ ^ _ _ r _ _ _ 1961b. The ef f e c t of pressure on the su r v i v a l and d i s t r i b u t i o n of l a r v a l and young f i s h . Ibid 26(3):292-311. 1962a. Reactions of l a r v a l and young salmonids to water of low oxygen concentration. Ibid 27 ( 2) :167-180 . 1962b. Reactions of l a r v a l and young salmonids to dif f e r e n t hydrogen ion concentrations. Ibid 2 7 ( 2 ) ; l 8 l - 1 9 1 . Brannon, E.L. 1965. The influence of physical factors on the development and weight of sockeye salmon embryos and a l e v i n s . Int. Pac. Salmon P i s h . Comm., Prog. Rept. 12:1-26. Briggs, J.C. 1953. The behaviour and reproduction of salmonid fishes i n a small coastal stream. C a l i f . F i s h and Game, F i s h . B u l l . 9Jt:l-62. Burner, C.J. 1951. Characteristics of spawning nests of Columbia River salmon. U.S. Pish and W i l d l i f e Service, P i s h . B u l l . £2(61) : 9 7 - H 0 . Campbell, H.J. 1954. T^e ef f e c t s of s i l t a t i o n from gold dredging on the survival of rainbow trout and eyed eggs i n Powder River, Oregon. Oregon State Game Comm., Oregon. 3p (processed). C a r l , G.C. 1940* Comparison of coho salmon f r y from eggs incubated i n gravel and i n hatchery baskets. Trans. Am. Pis h . Soc. 69:132-134. -80-Coble, D.W. 1 9 6 1 . Influence of water exchange and d i s s o l v e d oxygen .in redds on s u r v i v a l of steelhead t r o u t embryos. Trans. Am. P i s h . Soc. 9Otl4.69-l1.7ii. Cooper, A.C. 1 9 6 5 . The e f f e c t of t r a n s p o r t e d stream sediments on the s u r v i v a l of sockeye and pink salmon eggs and a l e v i n s . I n t . Pac. Salmon P i s h . Comm., B u l l . 17 :1-71. Cordone, A . J . and D.W. K e l l e y , 1 9 6 1 . The i n f l u e n c e s o f inorganic sediment on the aquatic l i f e of streams. C a l i f . P i s h and Game, 1*7.(2) : 1 8 9 - 2 2 8 . Davies, O.L.(ed.) 1 9 5 6 . Design and A n a l y s i s of I n d u s t r i a l  Experiment. Hafner, New York. 636 pp. D i l l , L;.M. 1 9 6 7 . Studies on the e a r l y feeding of sockeye salmon a l e v i n s . Can. P i s h C u l t . 3 9 : 2 3 - 3 1 * . D i s l e r , N.N. 1 9 5 1 . E c o l o g i c a l and morphological c h a r a c t e r i s t i c s of the development of the Amur autumn chum salmon, Oncorhynchus keta (Walb.). I n : P a c i f i c Salmon: Selected A r t i c l e s from Soviet P e r i o d i c a l s . I s r a e l Program f o r S c i e n t i f i c T r a n s l a t i o n , Jerusalem I 9 6 I . O f f i c e of Technical S e r v i c e s , U.S. Dept. of Commerce, Washington, pp 33-1*1. P o e r s t e r , R.E. and W. R i c k e r , 1 9 5 3 . The coho salmon of Cultus Lake and Sweltzer Creek. J . P i s h . Res. Bd. Canada, 10(6):293-319. Gangmark, H.A. and R.G. Bakkala, i 9 6 0 . A comparative study of unstable and s t a b l e ( a r t i f i c i a l channel) spawning streams f o r inc u b a t i n g king salmon at M i l l Creek. C a l i f . P i s h and Game, 1*6(2) : 151-161*. Geiger, W. and H. Roth, 1 9 6 2 . Beobachtungen an k u n s t l i c h e n F o r e l l e n l a i c h g r u b e n . Schweiz . Z. H y d r o l . 21* : 7 6 - 8 9 . H a r r i s o n , C.W. 1923. P l a n t i n g eyed salmon and t r o u t eggs. Trans. Am. P i s h . Soc. 5 3 : 1 9 1 - 2 0 0 . Hartman, W.L., S t r i c k l a n d , C.W., and D.T. Hoopes, 1 9 6 2 . S u r v i v a l and behaviour o f sockeye salmon f r y migrating i n t o Brooks Lake, A l a s k a . Trans. Am. F i s h . Soc. 9 1 ( 2):1 3 3 - 1 3 9 . Heard, W.R. I 9 6 I * . P h o t o t a c t i c behaviour of emerging sockeye salmon f r y . Anim. Behav. 1 2 ( 2 - 3):3 8 2 - 3 8 8 . Hoar, W.S. 1 9 5 8 . The e v o l u t i o n of migratory behaviour among j u v e n i l e salmon of the genus Oncorhynchus. J . F i s h . Res. Bd. Canada, l£ ( 3 ) : 3 9 l - i * 2 8 . Hobbs, D.P. 191*8. Trout f i s h e r i e s i n New Zealand, t h e i r development and management. New Zealand Marine Dept. P i s h . B u l l . 9 : 1 - 1 7 5 . -81-Hunter, J.C. 1959. Survival and production of pink and chum salmon i n a coastal stream. J . F i s h . Res. Bd.v Canada, 16(6):835-886. Koski, K.V. 1966. The su r v i v a l of coho salmon from egg deposition to emergence i n three Oregon coastal streams. MSc. Thesis, Oregon State Univ., C o r v a l l i s , Oregon. 8I4. pp. Kusnetzov, I . I . 1928. Some observations of the Amur and Kamtchatka salmons. B u l l e t i n of the P a c i f i c S c i e n t i f i c Fishery Res. Sta., Vladivostok 2(3):1-195. F i s h . Res. Bd. Canada, Translation #22. Lagler, K.F. 1956. Freshwater Fishery Biology. Dubuque, Iowa. 1+21 pp. McNeil, W.J. 1962. Mortality of pink and chum salmon eggs and larvae i n Southeast Alaska streams. PhD. Thesis, Univ. of Wash., Seattle, Washington. 270 pp. I 9 6 3 . Quality of the spawning bed as i t relates to su r v i v a l and growth of pink salmon embryos and alevins and time of f r y emergence. 16th. Int. Cong. Zool., Proc. 1:214.2 (abstract o n l y ) . 1966. E f f e c t of the spawning bed environment on reproduction of pink and chum salmon. U.S. Fish and W i l d l i f e Serv., F i s h . B u l l . 65(2):495-525. and W.H. Ahnell, I96I4.. Success of pink salmon spawning r e l a t i v e to size of spawning bed materials. U.S. F i s h and W i l d l i f e Serv., Spec. S c i . Report, F i s h . I4.69. 15 PP. Marr, D.H.A. 1963. The influence of surface contour on the behaviour of trout a l e v i n s , S. t r u t t a L. Anim. Behav. 11(2-3) :1+12. 1965. Tbe influence of l i g h t and surface contour on the e f f i c i e n c y of development of the salmon embryo. Rep. Challenger S o c , 3(XVII):33 Mason, J.C. and D.W. Chapman, 1965. Significance of e a r l y emergence, environmental rearing capacity, and behavioural ecology of juvenile coho salmon i n stream channels. J . F i s h . . Res. Bd. Canada, 22(1):173-190. M e r r e l l , T.R., J r . 1962. Freshwater s u r v i v a l of pink salmon at Sashin Creek, Alaska. In: A Symposium on Pink Salmon. N.J. Wilimovsky (ed.), University of B r i t i s h Columbia, Vancouver, B. C , i 9 6 0 , pp 59-72. Neave, F. 19.47 • Natural propagation of chum salmon i n a coastal stream. F i s h . Res. Bd. Canada, Prog. Rept. Pac. Coast Sta., 70:20-21. - 8 2 -Neave, P. 1953* P r i n c i p l e s a f f e c t i n g the si z e of pink and chum salmon populations i n B r i t i s h Columbia. J . Pish.. Res. Bd. 9(9):1|50-1*91. 1955. Notes on the seaward m i g r a t i o n of p i n k and chum salmon f r y . J . P i s h . Res. Bd. Canada, 12:369-3714-. P h i l l i p s , R.W. 1965. E f f e c t of f i n e m a t e r i a l on salmon and tr o u t redds. Proc. Meeting on Erosion and Sedimentation i n the Northwest, 196*4.-65 Flood Season. U.S. Dept. A g r i c u l t u r e , S o i l Conservation S e r v i c e , P o r t l a n d , Oregon. , and H.J. Campbell, 1961. The embryonic s u r v i v a l of coho salmon and steelhead t r o u t as i n f l u e n c e d by some environmental c o n d i t i o n s i n g r a v e l beds. Pac. Mar. F i s h . Comm. Rept. 3 4 : 6 0 - 7 3 . , and E.W. C l a i r e , 1966. I n t r a g r a v e l movement of the r e t i c u l a t e s c u l p i n , Cottus perplexus, and i t s p o t e n t i a l as a predator on salmonid embryos. Trans. Am. P i s h . Soc. 9 5 ( 2 ) : 2 1 0 - 2 1 2 . P r i t c h a r d , A.L. 1914-7. E f f i c i e n c y of n a t u r a l propagation of P a c i f i c salmon. Can. P i s h . C u l t . l ( 2 ) : 2 2 - 2 6 . Roth, H. and W. Oeiger, 1963. Experimentelie Untersuchungen uber das Verhalten der Bachf o r e l l e n b r u t i n der Laichgrube. Schweiz. Z. Hy d r o l . 2 5 ( 2 ) : 2 0 2 - 2 1 8 . Royce, W.F. 1959. On the p o s s i b i l i t i e s of improving salmon spawning areas. Trans. N.A. W i l d l i f e Conf. 21).:356-366. Shapovalov, L. and W. B e r r i a n , I9I4.O. An experiment i n hatching s i l v e r salmon (Oncorhynchus k i s u t c h ) eggs i n g r a v e l . Trans. Am. P i s h . Soc. b9:135-li+0T* Shaw, P.A. and J.A. Maga, 191+3 - The e f f e c t of mining s i l t on y i e l d of f r y from salmon spawning beds. C a l i f . P i s h and Game, 29:29-14.1. Shelton, J.M. 1955. The hatching of chinook salmon eggs under simulated stream c o n d i t i o n s . Progr. P i s h . C u l t . 17:20-35* , and R.D. P o l l o c k , 1966. S i l t a t i o n and egg s u r v i v a l i n i n c u b a t i o n channels. Trans. Am. P i s h . Soc. 9£(2):183-187. Sheridan, W.L. and W.J. McNeil, i 9 6 0 . E f f e c t s o f logging on the p r o d u c t i v i t y o f pi n k salmon streams i n A l a s k a . Univ. of Wash. F i s h . Res. I n s t i t . , C o n t r i b . j 7 : l 6 - 1 7 . Shumway, D.L., Warren, C.E., and P. Doudoroff, 1961*. The in f l u e n c e of oxygen concentrations and water movement on the growth of steelhead t r o u t and coho salmon embryos. Trans. Am. P i s h . Soc. 93 (k) :3l*2-3l|-3. - 8 3 -S i l v e r , S.J., Warren, G.S., and P. Doudoroff, 1963. Dissolved oxygen requirements of developing steelhead trout and chinook salmon embryos at di f f e r e n t water v e l o c i t i e s . Trans. Am. F i s h . Soc . 92(ij.) :327-3ij-3. Steel, R.G.D. and J.H. Torrie, I 9 6 0 . P r i n c i p l e s and Procedures  of S t a t i s t i c s . McGraw H i l l , Toronto"! 1*81 pp. Stuart, T.A. 1953 • Spawning migration,.reproduction, and young stages of Loch trout (Salmo t r u t t a L . ) . Scottish Home. Dept., Freshwater and Salmon F i s h . Res., 5 : 1 - 3 9 . Wales, J.H. and M. Coots, 1955• E f f i c i e n c y of chinook salmon spawning in F a l l Creek, C a l i f o r n i a . Trans. Am. F i s h . Soc., 8^:137-114.9. White, G.M. 1915. The behaviour of brook trout embryos from the time of hatching to the absorption of the yolk sac. J . Anim. Behav., 5 :144-60. White, H.C. I9I4.2. A t l a n t i c salmon redds and a r t i f i c i a l spawning beds. J . F i s h . Res. Bd. Canada, 6(1) :37-l|4. Wickett, W.P. 19514-• The oxygen supply to salmon eggs i n spawning beds. J . F i s h . Res. Bd. Canada, 11:933-953. 1962. Environmental v a r i a b i l i t y and reproduction potentials of pink salmon in B r i t i s h Columbia. In: A Symposium on Pink Salmon. N.J. Wilmovsky (ed.),.University of B r i t i s h Columbia, Vancouver, B. C., i 9 6 0 , pp 73-86. Woodhead, P.M.J. 1957. Reactions of salmonid larvae to l i g h t . J . Exp. B i o l . ^:1|.02-14.16. 

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