UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

The movement and competitive behaviours of male coho salmon (Oncorhynchus kisutch) reproductive tactics Prince, Angela 1997

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-ubc_1998-0046.pdf [ 3.74MB ]
Metadata
JSON: 831-1.0074812.json
JSON-LD: 831-1.0074812-ld.json
RDF/XML (Pretty): 831-1.0074812-rdf.xml
RDF/JSON: 831-1.0074812-rdf.json
Turtle: 831-1.0074812-turtle.txt
N-Triples: 831-1.0074812-rdf-ntriples.txt
Original Record: 831-1.0074812-source.json
Full Text
831-1.0074812-fulltext.txt
Citation
831-1.0074812.ris

Full Text

THE MOVEMENT AND COMPETITIVE BEHAVIOURS OF MALE COHO SALMON (ONCOEHYNCHUS KISUTCH) REPRODUCTIVE TACTICS. by Angela Prince B . S c , The U n i v e r s i t y of Toronto, 1991 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES (Department of Zoology) We accept t h i s t h e s i s as conforming to the_ required standards THE UNIVERSITY OF BRITISH COLUMBIA December, 1997 © Angela Prince, 1997 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department The University of British Columbia Vancouver, Canada DE-6 (2/88) Abstract The p r e v a i l i n g view regarding the f i t n e s s , e v o l u t i o n and maintenance of male coho mating s t r a t e g i e s has been based on pieces of data from d i f f e r e n t salmon species. Since there i s no reason to suppose that a l l salmon species are the same, there i s a need f o r a q u a n t i t a t i v e d e s c r i p t i o n of male coho salmon breeding behavior. The focus of t h i s t h e s i s i s to provide a d e t a i l e d e t h o l o g i c a l study of male coho spawning behavior w i t h the o b j e c t i v e of q u a n t i f y i n g 1) patterns of movements, and 2) i n t e r a c t i o n s among males of d i f f e r e n t reproductive t a c t i c s ( a l p h a , s a t e l l i t e , j a c k ) , and breeding groups. Because models that address the e v o l u t i o n and maintanence of reproductive s t r a t e g i e s r e q u i r e estimates of t a c t i c f i t n e s s f o r comparison, a secondary o b j e c t i v e was to use the q u a n t i t a t i v e data c o l l e c t e d to speculate about costs of reproduction f o r a l t e r n a t i v e reproductive t a c t i c s . In t o t a l , 43 male coho were captured and r a d i o tagged d u r i n g the 1992 and 1993 spawning escapements i n Kanaka Creek. Dominant hooknose males moved w i t h i n a r e s t r i c t e d stream segment (mean d a i l y d i stance (m) moved 86.33 SE 12.55) accessing the females w i t h i n the segment. S a t e l l i t e hooknose males moved both frequently and e x t e n s i v e l y (mean d a i l y distance (m) moved 661.94 SE 200.13), o f t e n e n t e r i n g d i f f e r e n t waterways during t h e i r breeding l i f e s p a n . Jack males were found to r e s i d e i n a small segment of stream throughout t h e i r breeding l i f e s p a n (mean d a i l y d i s t a n c e (m) moved 46.3 SE 40.3) and made use of a v a r i e t y of refuges, i n c l u d i n g the nest i t s e l f , from which to 'sneak' f e r t i l i z a t i o n s . S ixty-two breeding groups were i d e n t i f i e d , each having a anywhere from one to f i v e male group members. Rates of aggressive i n t e r a c t i o n s (mean i n t e r a c t i o n s per 10 minutes) were found to d i f f e r s i g n i f i c a n t l y among males adopting d i f f e r e n t r e p r o d u c t i v e t a c t i c s (P < 0.001). Alpha males had the highest rate of aggressive i n t e r a c t i o n s (15.2 SE 2.9 ) compared to a l t e r n a t i v e male behaviors ( f i r s t s a t e l l i t e 4.7 SE 0.9, second s a t e l l i t e 5.7 SE 1.3, and jack 2.4 SE 0.9). Aggression l e v e l s were found to d i f f e r s i g n i f i c a n t l y among mating groups ( 0.01 > P > 0.025). Intermediate s i z e groups had the lowest aggression l e v e l , 11.57 SE 3.81 i n t / 1 0 min (2 males) and 13.49 SE 3.87 int/ 1 0 min (3 males). The highest l e v e l of competitive i n t e r a c t i o n s occurred when only one male and one female were present (29.05 SE 12.50 int/ 1 0 min). P a i r s of combatants explained the i n c r e a s i n g r a t e of aggression with group s i z e f o r groups c o n t a i n i n g more than one reproductive t a c t i c (2 to 5 males)(0.75 <P< 0.90). Environmental c o n d i t i o n s on the spawning grounds influenced male behavior. Entry i n t o t r i b u t a r i e s was c o r r e l a t e d w i t h p r e c i p i t a t i o n . When temperatures and flow i i i decreased d r a m a t i c a l l y during the week of Dec 20-26 (1993) , manoe u v r a b i l i t y was i n h i b i t e d , and movement decreased. During storm events i n Thornvale Creek, t u r b i d i t y i n c r e a s e d and spawning behavior ceased. As season progressed and a v a i l a b l e females decreased, males were observed to engage i n es c a l a t e d contests i n the absence of females. The evidence gathered during t h i s i n v e s t i g a t i o n i n d i c a t e s t h a t the e v o l u t i o n and maintenance of male coho mating s t r a t e g i e s i s more complex than p r e v i o u s l y described. Hooknose males that adopt a l t e r n a t i v e reproductive t a c t i c s d i f f e r s i g n i f i c a n t l y i n t h e i r m i g r a t i o n distances on the spawning grounds and ra t e s of competitive i n t e r a c t i o n s . Furthermore, there i s a s t r i c t adherence to b e h a v i o r a l t a c t i c s and an abundance of intermediate s i z e d males i n the p o p u l a t i o n . Thus, the r e s u l t s of t h i s study support the idea that the s a t e l l i t e t a c t i c i s not an unsuccessful one. i v TABLE OF CONTENTS Abstract i i TABLE OF CONTENTS v LIST OF TABLES v i i LIST OF FIGURES i x Acknowledgements x i INTRODUCTION 1 STUDY AREA 8 CHAPTER I MOVEMENT PATTERNS OF MALE COHO ON THE SPAWNING GROUNDS . . . 11 Introduction 11 Methods 14 Migration Phase II: movement prior to association with a spawning group 14 Migration Phase III: movement after association with a spawning group 15 Results 16 Migration Phase II: movement prior to association with a spawning group 16 Migration Phase III: movement after association with a spawning group 23 Discussion 34 v CHAPTER II COMPETITIVE INTERACTIONS OF MALE COHO ON THE SPAWNING GROUNDS 40 Introduction 40 Methods 43 Data Analysis 46 Results 52 Rates of aggressive interactions for males adopting alternative reproductive tactics 52 Effects of group formation and group size on rates of aggressive interaction 62 Discussion 69 CHAPTER III INFLUENCE OF ENVIRONMENT ON Behavior 76 Introduction 76 Methods 78 Results 78 Discussion 84 SUMMARY AND CONCLUSIONS 88 Bibliography 94 Appendix 101 v i LIST OF TABLES Table 1.1 Numbers of coho males radio tagged during two years of study. Brackets s i g n i f y number of i n d i v i d u a l s omitted from analysis as a r e s u l t of predation or signal loss within 48 hours of release 18 Table 1.2 Length (cm) and weight (kg) measurements of coho breeding group males captured f o r radio tagging i n 1993. Note that the largest male i n a group i s always dominant. 24 Table 2.1 Agonistic behaviors observed and scored f o r male coho. • . . 45 Table 2.2 Numbers of observations on groups of males adopting d i f f e r e n t reproductive t a c t i c s used i n competitive i n t e r a c t i o n analysis 48 Table 2.3 Competitive interactions of male coho adopting alternative reproductive t a c t i c s . Rates of male competitive interactions d i f f e r across reproductive t a c t i c s (P < 0.001) by Kruskall-Wallis ANOVA 53 Table 2.4 Competitive interactions of radio tagged coho males. Mean rates of interaction per 10 minutes for males adopting a l t e r n a t i v e reproductive t a c t i c s . . . 55 Table 2.5 Breeding groups observed i n Donovan and Thornvale Creeks during 1993/94 surveys. Group types i d e n t i f i e d contained one to f i v e males. In t o t a l , 62 breeding groups were observed 63 Table 2.6 Summary of male competitive interactions i n r e l a t i o n to breeding groups. Rates of male competitive interactions d i f f e r across breeding groups of 1 to 5 males (0.01 < P < 0.025) and across groups of 2 to 5 males (0.005 < P < 0.01) 64 Table 2.7 Rates of male competitive interactions among group members only ( i . e . interactions with intruder males removed). Rates of male competitive in t e r a c t i o n s among group members d i f f e r across breeding groups of 2 to 5 males (P < 0.001) 67 v i i Table 2.8 Rates of male competitive interactions expressed as a function of the number of males i n a group. Rates of male competitive interactions as a function of p a i r s of combatants do not d i f f e r across breeding groups of 2 to 5 males (0.75 < P < 0.90) 68 Table 3.1 Physical c h a r a c t e r i s t i c s of coho spawning habitat i n Kanaka Creek and two of i t s t r i b u t a r i e s , Donovan and Thornvale Creeks. Habitat measurements coincide with the beginning of the coho run i n 1993 80 Table 3.2 Male-male competitive interactions i n the absence of females. This behavior was not observed during the peak of the run. Levels of competitive investment are s i m i l a r to those when a female i s present and a c t i v e l y digging. . 85 Appendix: Physical c h a r a c t e r i s t i c s of Thornvale and Donovan Creeks 98 v i i i LIST OF FIGURES Figure 1.1 Kanaka Creek study area. Donovan and Thornvale Creeks contain majority of coho spawning locations 1992/93 (Murdoch, 1988) 9 Figure 1.2 Periodicity of movement and a c t i v i t y f o r a s a t e l l i t e male during four consecutive days of observation, 9 to 12 December, 1992. Soli d lines indicate periods of continuous observation 19 Figure 1.3 Movement of male coho l i f e h i s t o r y strategies p r i o r to association with a breeding group, 1992. At time of capture, males did not have f u l l y developed secondary sexual c h a r a c t e r i s t i c s 21 Figure 1.4 Exploratory movements of a large hooknose male pr i o r to joining a mating group i n November, 1992. . . .22 Figure 1.5 Length-frequency d i s t r i b u t i o n of 34 male coho captured and radio tagged during the 1993 spawning run i n Kanaka Creek. Males are grouped by reproductive t a c t i c ; Alpha, S a t e l l i t e and Jack. The s o l i d l i n e represents length-frequency data c o l l e c t e d on male coho captured at the counting fence on Kanaka Creek during the 1987/88 run (Murdoch 1988, n = 99) 25 Figure 1.6 Movement patterns of male coho that adopted d i f f e r e n t reproductive t a c t i c s a f t e r association with a breeding group. Males represent i n d i v i d u a l s captured and tagged from 28 November to 10 December, 1993 during the peak of the spawning period 26 Figure 1.7 Mean d a i l y distance (+/-SE) moved by male coho adopting d i f f e r e n t reproductive t a c t i c s . Males represent i n d i v i d u a l s captured and tagged from 28 November to 10 December, 1993 during the peak of the spawning period. 28 Figure 1.8 Movement of dominant or alpha males i n r e l a t i o n to i n d i v i d u a l females accessed. Each l e t t e r represents a p a r t i c u l a r female. Figure t i t l e s i ndicate month and Creek of o r i g i n a l capture 29 i x Figure 1.9 Movement of three s a t e l l i t e males i n 1993. Figure t i t l e s i ndicate date and Creek of o r i g i n a l capture. Each box represents a time and l o c a t i o n record f o r a f i s h . Arrows indicate movement to a new waterway 30 Figure 1.10 Movement and type of refuge used by radio tagged jack males i n Donovan and Thornvale Creeks, 1993. Movement of the Donovan jack was between two redds i n close proximity. Movements of the Thornvale jacks were associated with accessing new females . 32 Figure 1.11 Frequency of refuge u t i l i z a t i o n by jacks i n Donovan and Thornvale Creeks 32 Figure 2.1 Mean rates of aggressive interactions (+/-SE) fo r male coho adopting alternative reproductive t a c t i c s . Rates of aggression d i f f e r s i g n i f i c a n t l y among t a c t i c s (P<0 . 001) 54 Figure 2.2 Frequency of competitive interactions among males adopting alternative reproductive t a c t i c s . Note alpha and jack males i n t e r a c t p r i m a r i l y with intruding males and s a t e l l i t e males with the alpha male. 56 Figure 2.3 Mean l e v e l s (+/-SE) of aggression i n r e l a t i o n to breeding group s i z e . Small and large breeding groups had more frequent competitive interactions than intermediate sized groups 65 Figure 3.1 Mean d a i l y temperature and p r e c i p i t a t i o n during f o r Kanaka Creek during the coho spawning period f o r both years of study (1992 and 1993) 81 Figure 3.2 Mean d a i l y distance (m) moved by male coho of d i f f e r e n t reproductive t a c t i c s i n r e l a t i o n to run period. The run interruption r e f l e c t s a period of low flows and temperatures (20 Dec to 26 Dec, 1993) 83 x Acknowledgements Thank you to doctors Mike Healey, Robin L i l e y , Mike Henderson and Don McPhail f o r guidance throughout the study and e d i t o r i a l reviews. S p e c i a l thanks to Mike Healey f o r h i s continued support and encouragement, i n t r o d u c i n g me to Kanaka Creek and f o r h i s many t r i p s out i n t o the f i e l d on c o l d and r a i n y winter n i g h t s , searching f o r coho. Randy Lake was instrumental i n data c o l l e c t i o n and deserves r e c o g n i t i o n f o r h i s e f f o r t s which included f i s h capture, tagging, r a d i o t r a c k i n g and s c o r i n g behavior. Thanks a l s o to John Heaven, Manager of the B e l l - I r v i n g Hatchery at Kanaka Creek f o r the use of f a c i l i t i e s , equipment, weather data and time devoted to the capture of male coho. Dr. Tony Kozak, advanced b i o m e t r i c s i n s t r u c t o r of the Fa c u l t y of For e s t r y , was extremely h e l p f u l i n d i s c u s s i o n s of data a n a l y s i s and i n t e r p r e t a t i o n . Thank you to the Westwater Research Centre f o r o f f i c e and l o g i s t i c a l support throughout my p e r i o d of study. x i INTRODUCTION The mating s t r a t e g y of an organism i s a fundamental component of f i t n e s s because i t determines success i n rep r o d u c t i o n . Many animals, p a r t i c u l a r l y males, d i s p l a y m u l t i p l e mating s t r a t e g i e s (salmonids: Schroder 1981, Chebanov 1980, Gross 1985, B a g l i n i e r e et al. 1991, Foote and L a r k i n 1988, Keenlyside and Dupuis 1988; i n s e c t s : Lawrence 1987; crustaceans: Shuster 1989, and arachnids: Whitehouse 1991). How these s t r a t e g i e s evolve has been the subject of much re s e a r c h (Maynard Smith 1982, Gross 1985, Gardner et al. 1987, Gross 1991, Reynolds et al. 1993, Hutchings and Myers 1994, Fleming and Gross 1994). S e v e r a l hypotheses have been proposed to account f o r the existence of more than one mating s t r a t e g y . B e h a v i o r a l t a c t i c s may be under d i r e c t genetic c o n t r o l as i n the pygmy s w o r d t a i l {Xiphophorus nigrensis, Zimmerer and Kallman 1989) or be c o n d i t i o n a l upon an environmental cue ( i e . l i g h t l e v e l s ) as i n T r i n i d a d i a n guppies (Reynolds et al. 1993). I f a l t e r n a t i v e t a c t i c s are to be e v o l u t i o n a r y s t a b l e they r e q u i r e ; 1) that the d i f f e r e n t actions have equal payoffs and 2) that the payoffs to a p a r t i c u l a r s t r a t e g y be n e g a t i v e l y frequency dependant (Smith 1982) . One of the most popular examples of a mixed e v o l u t i o n a r y s t a b l e s t r a t e g y comes from coho salmon {Oncorhynchus kisutch) 1 (Gross 1984, 1985, and 1991). J u v e n i l e coho emerge from the g r a v e l as f r y and spend the f i r s t twelve to twenty-four months feeding i n freshwater before migrating to the ocean as smolts. As they mature, they move up and down the coast feeding, many spending t h e i r e n t i r e marine l i f e i n c o a s t a l waters (Hartt and D e l l 1986). Populations of coho are d i s t r i b u t e d as f a r north as Kukpuk R i v e r near Point Hope on the Chukchi Sea and occur along the A s i a n and P a c i f i c coasts as f a r south as Monterey Bay, C a l i f o r n i a (Sandercock 1991) . The m a j o r i t y of males mature a f t e r eighteen months at sea and return to t h e i r n a t a l streams to spawn as three year o l d hooknose males. Some males; however, mature a f t e r only s i x months at sea and are known as j a c k s . Based on a v a r i e t y of s t u d i e s i n salmonids and other species d e a l i n g with b e h a v i o r a l t a c t i c s and reproductive success, a p a r t i c u l a r view of male coho reproduction has developed (Schroder 1981, Chebanov et al. 1983, Maekawa and Onozato 1986, Hutchings and Myers 1988, Zimmerer and Kallman 1989, Jordan and Youngson 1992, Gross 1985, Gross 1991) . According to t h i s view, once on the spawning grounds, there are two b e h a v i o r a l t a c t i c s males may employ to gain access to females, f i g h t i n g or sneaking. The l a r g e , hooknose males are b e t t e r equipped f o r f i g h t i n g as they have long kypes (upper jaw extension) w i t h enlarged t e e t h and d o r s a l humps ( c a r t i l a g e 2 deposits) which may serve to s h i e l d blows from opponents (Gross 1985) . By c o n t r a s t , jack males are small and have c r y p t i c c o l o r a t i o n making them b e t t e r s u i t e d f o r sneaking (Gross 1985) . Jack males are believed to be r e l i a n t upon s u i t a b l e refuges ( i e . shallow depressions or vegetation) to gain p r o x i m i t y to a female (Gross 1985, Gross 1991). Hiding i n these refuges, they may avoid i n j u r y from l a r g e r males. When gamete re l e a s e i s imminent, jack males rush i n t o the nest and p a r t i c i p a t e i n the f e r t i l i z a t i o n of the eggs and are thus r e f e r r e d to as "sneaks" (Gross 1985). Based on t h e i r p r o x i m i t y to the female r e l a t i v e to the dominant male, jack coho males have been estimated to achieve 66% of the f e r t i l i z a t i o n success of alpha males during spawning (Gross 1985). This estimate i s supported by experimentation t h a t c o r r e l a t e d f e r t i l i z a t i o n success of A t l a n t i c salmon parr w i t h nest entry order (Hutchings and Myers 1988). Measures of precocious male f e r t i l i z a t i o n success (determined w i t h e l e c t r o p h o r e t i c techniques) i n d i c a t e t h a t , on average, a precocious male D o l l y varden, Salvelinus malma miyabei f e r t i l i z e s 16.8%(Maekawa and Onozato 1986), and A t l a n t i c salmon p a r r f e r t i l i z e 5.0%, Salmo salar (Hutchings and Myers 1988) to 10.8% (Jordan and Youngson 1992) of the eggs. While a greater number of the eggs are f e r t i l i z e d w i t h i n c r e a s i n g numbers of p a r r (up to 23%), i n d i v i d u a l l y , the f e r t i l i z a t i o n success i s 3 reduced (Hutchings and Myers 1988). C a l c u l a t i o n s of the r e l a t i v e f i t n e s s of the hooknose and jack l i f e h i s t o r y s t r a t e g i e s , based on estimates of s u r v i v o r s h i p to m a t u r i t y , breeding o p p o r t u n i t i e s (corresponding to breeding l i f e s p a n ) and f e r t i l i z a t i o n success (estimated by p r o x i m i t y of the male to the female) , suggests that both s t r a t e g i e s have equal payoffs (Gross 1985). Furthermore, there i s evidence that w i t h i n each s t r a t e g y , male success i s negative frequency dependant (Hutchings and Myers 1988) and that body s i z e i s the t r a i t on which d i s r u p t i v e s e l e c t i o n operates (Gross 1985). In a d d i t i o n to p r o v i d i n g one of the best known examples of a mixed e v o l u t i o n a r y s t a b l e s t r a t e g y , the coho mating system also serves as an example of a l t e r n a t i v e t a c t i c s w i t h i n a s i n g l e s t r a t e g y . A l t e r n a t i v e behavior which depends on circumstance ( i . e . on p e r c e i v e d asymmetries) i s not e v o l u t i o n a r y s t a b l e as payoffs a s s o c i a t e d with each a c t i o n d i f f e r . Among the hooknose males, i n d i v i d u a l s compete f o r access to a female (Gross 1985) . A s i z e graded h i e r a r c h y i s e s t a b l i s h e d behind the spawning p a i r as s i z e i s c o r r e l a t e d w i t h competitive a b i l i t y (Gross 1985). The winner of a competition i s c l o s e s t to the female, c o u r t i n g and defending her against would be s u i t o r s . This dominant male i s also c a l l e d the alpha male and subordinate males behind the p a i r are c a l l e d s a t e l l i t e males. The a s s o c i a t i o n of males (sub-dominant and dominant) and a female i n a breeding assemblage i s r e f e r r e d to as a breeding group. 4 Measures of s a t e l l i t e male f e r t i l i z a t i o n success (determined using e l e c t r o p h o r e t i c techniques) i n d i c a t e that on average, a sub-dominant hooknose male sockeye salmon; Oncorhynchus nerka f e r t i l i z e s 10.0% (range: 1.6%-47.7%), (Chebanov et al. 1983) and a chum salmon; Oncorhynchus keta 25.5% (range: 0%-46%)(Schroder 1981) of the eggs. In c o n t r a s t , an alpha hooknose male f e r t i l i z e s 90% (sockeye) and 63% (chum range: 53%-100%) of the eggs. Thus, those hooknose males forced to occupy a s a t e l l i t e p o s i t i o n appear to be making the "best of a bad s i t u a t i o n " (BBS) (Maynard Smith 1982). Although reproductive payoffs ( i . e . f e r t i l i z a t i o n success) of the three mating t a c t i c s (alpha, s a t e l l i t e and jack/sneak) have been q u a n t i f i e d f o r s e v e r a l species ( A t l a n t i c salmon, chum salmon, sockeye salmon, and Miyabei char), such measurements are not a v a i l a b l e f o r coho. S i m i l a r l y , many of the reproductive b e h a v i o r s , i n c l u d i n g movement and competition, that have been des c r i b e d f o r other species ( A t l a n t i c salmon, chum salmon, sockeye salmon, pink salmon) remain to be resolved f o r coho. In f a c t , the p r e v a i l i n g view regarding the f i t n e s s , e v o l u t i o n and maintenance of male coho mating s t r a t e g i e s has been based on pieces of data from d i f f e r e n t species. Since there i s no reason to suppose that a l l salmon species are the same, there i s a need f o r a good, q u a n t i t a t i v e d e s c r i p t i o n of the breeding behavior and t a c t i c s of male coho. Consequently, the focus of 5 t h i s t h e s i s i s to provide a d e t a i l e d e t h o l o g i c a l study of male coho spawning behavior w i t h the o b j e c t i v e of q u a n t i f y i n g 1)patterns of movements, 2 ) i n t e r a c t i o n s of males adopting a l t e r n a t i v e r eproductive t a c t i c s , and 3 ) i n t e r a c t i o n s of males belonging to d i f f e r e n t breeding groups. Because models that address the evol u t i o n and maintenance of reproductive s t r a t e g i e s require estimates of t a c t i c f i t n e s s f o r comparison, a secondary o b j e c t i v e was to use the q u a n t i t a t i v e data c o l l e c t e d to speculate about the reproductive costs f o r a l t e r n a t i v e male reproductive t a c t i c s . The f i r s t chapter examines the movement p a t t e r n s of male coho on the spawning grounds. Observations of chum salmon i n an experimental stream channel showed that males dominated by two or more males moved on i n search of other a v a i l a b l e females r a t h e r than occupying a subordinate p o s i t i o n (Schroder 1981). Assuming that coho s a t e l l i t e males are s i m i l a r to sockeye and chum s a t e l l i t e males i n t h e i r f e r t i l i z a t i o n success ( r e c a l l that s a t e l l i t e s of these species achieved fewer f e r t i l i z a t i o n s than the alpha male)(Chebanov et al. 1983, Schroder 1981), competitively i n f e r i o r males ( s a t e l l i t e s ) were expected to move more i n an attempt to access a d d i t i o n a l females and maximize reproductive success. Chapter two q u a n t i f i e s the competitive i n t e r a c t i o n s of the male mating t a c t i c s . The p o t e n t i a l r eproductive b e n e f i t of 6 each p o s i t i o n i n the h i e r a r c h y was expected to be r e f l e c t e d i n the amount of energy expended i n defence. S p e c i f i c a l l y , more frequent and vigorous competitive i n t e r a c t i o n s were expected to occur among hooknose males f i g h t i n g f o r the p o s i t i o n next to the female. Jack males were expected to have few aggressive i n t e r a c t i o n s with hooknose males as they are hidden i n refuges, l i m i t e d by energy reserves and would l i k e l y s u f f e r s e r i o u s i n j u r y i f attacked. Jack males, however, were expected to compete among themselves f o r refuges (Gross 1985). The f i n a l chapter considers the p a t t e r n s of movement and competition w i t h i n the spawning area, i n r e l a t i o n to environmental c o n d i t i o n s . Habitat type, temperature, flow and season were recognized as f a c t o r s l i k e l y to i n f l u e n c e spawning behavior. While no formal t e s t i n g was conducted to determine the e f f e c t of the p h y s i c a l c o n d i t i o n s on behavior, data c o l l e c t e d from h a b i t a t mapping, data loggers and i n c i d e n t a l observations were considered i n i n t e r p r e t i n g r e s u l t s . Since salmon cease feeding upon t h e i r r e t u r n spawning m i g r a t i o n s , the a l l o c a t i o n of energy reserves i s c r i t i c a l i n determining l i f e t i m e reproductive success as breeding l i f e s p a n corresponds w i t h breeding o p p o r t u n i t i e s (Gross 1985, van den Berghe and Gross 1986). Reproductive success r e a l i z e d i n any one spawning event w i l l be devalued by the costs r e q u i r e d to search f o r that female and maintain p o s i t i o n w i t h i n a mating group. 7 The i n f o r m a t i o n gathered on male movement and competitive investments i n t h i s study i s considered i n terms of the f i t n e s s of the d i f f e r e n t reproductive t a c t i c s and the maintenance of phenotypes w i t h i n the po p u l a t i o n . The r e s u l t s have been combined to give a comprehensive overview of f a c t o r s that may have played a r o l e i n the evolu t i o n of reproductive behavior and st r a t e g y i n male coho. STUDY AREA Kanaka Creek, l o c a t e d approximately 62 km east of Vancouver, B. C , i s a t r i b u t a r y to the Fraser R i v e r . O r i g i n a t i n g from Blue Mountain Forest i n Maple Ridge D i s t r i c t M u n i c i p a l i t y , i t flows southwest f o r 19 km through mature second growth f o r e s t , canyons, meadows and f i n a l l y t i d a l marshes, entering the Fraser River northwest of McMillan I s l a n d (Murdoch, 1988) . Salmon spawning h a b i t a t i n Kanaka Creek i s r e s t r i c t e d by a set of impassable f a l l s at C l i f f F a l l s Park (Figure 1.1). The bottom f a l l s , l o c a t e d approximately 6.8 km upstream from the mouth, presents a 3 m high rock b a r r i e r which are impassable d u r i n g low flows. The top f a l l s , above which Kanaka Creek s p l i t s i n t o two branches, i s approximately 7.6 km upstream from 8 F i g u r e 1.1 Kanaka c r e e k s t u d y a r e a . Donovan and T h o r n v a l e c r e e k s c o n t a i n m a j o r i t y o f coho spawning l o c a t i o n s 1992/93 (Murdoch, 1988) . 9 the mouth, and presents a 6 m high rock b a r r i e r which are impassable to a l l anadromous salmonids. Kanaka Creek flows past, and feeds B e l l - I r v i n g Hatchery, located on i t s south fork, approximately 16 km above C l i f f F a l l s Park (Murdoch, 1988). There are three small t r i b u t a r i e s below the lower f a l l s : Lamb, Thornvale and Donovan Creeks (Figure 1.1). Kanaka Creek and i t s t r i b u t a r i e s are subject to f l a s h f l o o d i n g . Only Thornvale and Donovan Creeks are a c c e s s i b l e to spawning salmonids. Lamb Creek had spawning coho documented i n a 1987/88 spawner survey (Murdoch, 1988); however, no spawning salmon were observed during t h i s study as p r i v a t e land owners had ba r r i c a d e d (with fencing) the t r i b u t a r y at i t s mouth. Thornvale Creek was als o b a r r i c a d e d , at 108 Th Avenue, by land f i l l and a c u l v e r t which was elevated 3-4 metres above the stream bed, l e a v i n g only 400 m of acc e s s i b l e stream h a b i t a t . Donovan i s a c c e s s i b l e up to 2.0 km from i t s mouth. 10 CHAPTER I MOVEMENT PATTERNS OF MALE COHO ON THE SPAWNING GROUNDS I n t r o d u c t i o n Over the geographic range of the species, coho salmon spawning migrations begin i n July/August and c a r r y through to March w i t h the m a j o r i t y of spawning o c c u r r i n g between November and January (Shapovalov and Taft 1954). In general, the higher the l a t i t u d e , the e a r l i e r the mi g r a t i o n (Briggs 1953) . Upon re a c h i n g freshwater, coho w i l l wait weeks, even months f o r su i t a b l e conditions of flow and temperature before e n t e r i n g the freshwater stream (Banks 1969, Sandercock 1991). As temperatures decrease and flows increase, coho begin t h e i r freshwater migrations upstream during daylight' hours (Sandercock 1991). The freshwater migration of returning adult salmon has been c h a r a c t e r i z e d as having three d i s t i n c t phases: 1) Rapid continuous upstream movement followed by; 2) a delay or residence p e r i o d spent i n s h e l t e r e d pools before; 3) movement onto spawning beds (Heggberget et a l . 1988, B a g l i n i e r e et a l . 1990). Previous accounts of coho movement (Neave 1943, Shapovalov and Taft 1954, E l l i s 1962, Sandercock 1991) have been l i m i t e d to the f i r s t two phases of mi g r a t i o n as the m a j o r i t y of information stems from observations made at fishways l o c a t e d on 11 l a r g e r creeks and r i v e r s . Since coho spawn i n s m a l l , o f t e n f a r reaching t r i b u t a r i e s (Briggs 1953, Murdoch 1988), movement and d i s t r i b u t i o n on the spawning grounds has received l e s s a t t e n t i o n (Heggberget et a l . 1988, B a g l i n i e r e et a l . 1990). In a system where males compete f o r access to females, male d i s t r i b u t i o n and mating success can be understood only by observing i n d i v i d u a l male a c t i v i t y (Otronen 1993) . In t h i s way, i n v e s t i g a t o r s gain an understanding of the d e c i s i o n s ( i . e . trade o f f s ) made over an i n d i v i d u a l ' s breeding l i f e s p a n . Since movement i s a cost of reproduction f o r male salmon (Lucas et a l . 1993), documenting movement i n r e l a t i o n to male reproductive t a c t i c s may provide i n s i g h t regarding the e v o l u t i o n and maintenance of a l t e r n a t i v e s t r a t e g i e s i n salmon p o p u l a t i o n s . With the advent of rad i o telemetry, researchers are now able to c o l l e c t d e t a i l e d and continuous observations on i n d i v i d u a l behavior and movement of f i s h i n t h e i r n a t u r a l environment. Telemetric studies of male salmon movements on the spawning grounds have uncovered complex behavior p a t t e r n s that are not e a s i l y g e n e r a l i z e d (Power and McCleave 1980). For example, i n a study on A t l a n t i c salmon, Webb and Hawkins (1989) observed a number of male a c t i v i t y p a t t e r n s . In one p a t t e r n , males moved to a p a r t i c u l a r short length of stream and remained there u n t i l spawning. In a second p a t t e r n , males moved ext e n s i v e l y between the main spawning areas before s u c c e s s f u l l y 12 spawning. In a t h i r d p a t t e r n , e x h i b i t e d p a r t i c u l a r l y by g r i l s e (precocious) males, i n d i v i d u a l s moved frequently and e x t e n s i v e l y between the main spawning areas, but achieved few s u c c e s s f u l p a i r i n g s . The researchers concluded that the frequency and amplitude of movements was not n e c e s s a r i l y an i n d i c a t o r of spawning success, but r a t h e r , a long stay i n a small segment of stream was i n d i c a t i v e of spawning success. A d d i t i o n a l evidence which r e l a t e s movement to reproductive success i s provided, by male chum salmon. Schroder (1981, 1982) showed th a t a male dominated by two or three r i v a l s i n a spawning group, tended to leave r a t h e r than stay and occupy a subordinate p o s i t i o n . Schroder (1981) argued t h a t , because these subordinate males o b t a i n almost no f e r t i l i z a t i o n success, they should leave i n search of another a v a i l a b l e female. In other words, those males that are small or weak should spend more time searching f o r an a v a i l a b l e female (Schroder 1981). In t h i s i n v e s t i g a t i o n , r a d i o telemetry was used to compare i n d i v i d u a l movement patterns of male coho adopting a l t e r n a t i v e reproductive t a c t i c s (alpha, s a t e l l i t e and jack) on the spawning grounds. I pr e d i c t e d that the smaller, s a t e l l i t e hooknose males would e x h i b i t greater movement w i t h i n the spawning area than l a r g e r , alpha hooknose males. Further, i n accordance w i t h Schroder's (1981) observations, secondary s a t e l l i t e males, (dominated by two males: alpha and f i r s t s a t e l l i t e ) , were 13 expected to move more f r e q u e n t l y and e x t e n s i v e l y than f i r s t s a t e l l i t e and alpha males. F i n a l l y , because precocious coho males (jacks) are thought to be r e s t r i c t e d by energy reserves and s u i t a b l e refuges from which to "sneak" f e r t i l i z a t i o n s (Gross 1985), two year o l d jack males were expected to show the l e a s t amount of movement on the spawning grounds. Methods Migration Phase II : movement prior to association with a spawning group Studies of movement were made by r a d i o tagging f i s h and monitoring t h e i r movements and l o c a t i o n throughout stream l i f e . To determine movements of males p r i o r to spawning, i n d i v i d u a l males were captured (Oct & Nov, 1992) at a counting fence i n Kanaka Creek and transported to the B e l l - I r v i n g hatchery l o c a t e d upstream from the fence. Three weight categories were chosen to represent the d i f f e r e n t reproductive t a c t i c s : 2-4 kg (alpha males), 1-2 kg ( s a t e l l i t e males) and <1 kg ( j a c k s ) . P r i o r to tag attachment, males were anaesthetized w i t h 2-phenoxy ethanol to reduce handling s t r e s s . A f t e r weight and f o r k l e n g t h were recorded, males were placed on t h e i r d o r s a l surface and using a s m a l l p l a s t i c tube ( l u b r i c a t e d w i t h mineral o i l ) as a guide, a t r a n s m i t t e r (14 X 45 mm) was d e l i v e r e d to the stomach l e a v i n g the antenna t r a i l i n g from the mouth. G a s t r i c i n s e r t i o n was chosen as the method of transmitter attachment as i t i s a r a p i d , 14 non-invasive technique that does not increase drag and has a low p r o b a b i l i t y of ex p u l s i o n given that spawning salmon are not feeding (Mellas and Haynes, 1985). F i n a l l y , coloured Floy tags were attached j u s t behind the d o r s a l f i n to a i d i n v i s u a l i d e n t i f i c a t i o n . F i s h were allowed to recover f o r one hour before being t r a n s p o r t e d back to Kanaka Creek where they were r e l e a s e d 1500 m above the counting fence (Figure 1.1) . A three-element Yagi antenna and an SRX 400 r e c e i v e r (Lotek Eng. Inc.) was used to l o c a t e i n d i v i d u a l s on the spawning grounds. The movement and p o s i t i o n of males was monitored f o r one hour observation periods during both day and n i g h t . Migration Phase III: movement after association with a spawning group The two spawning t r i b u t a r i e s of Kanaka Creek, Donovan and Thornvale Creeks, were surveyed (Nov./Dec. 1993 & Jan. 1994) f o r spawning groups. Once lo c a t e d , a spawning group was observed for one hour to determine each male's p o s i t i o n and reproductive t a c t i c . Members of the group were captured by hand, beginning at the downstream end of the h i e r a r c h y such that other males were not d i s t u r b e d . Jacks were captured l a s t w i t h a dip net. Three classes of tags ( 14 X 45 mm, 14 X 40 mm, and 11.2 X 37.5 mm) were used so that the weight of the tag i n water d i d not exceed 1.5% of the weight of the f i s h i n a i r . Transmitters were i n s e r t e d i n t o the f i s h (see above) on the bank adjacent to the 15 capture s i t e . Weight, fork length and c o n d i t i o n were recorded. Indices of c o n d i t i o n recorded i n c l u d e d development of secondary sexual c h a r a c t e r i s t i c s , s c a l e r e s o r p t i o n , f i n c o n d i t i o n (wearing/erosion) and fungal i n f e c t i o n s . Each index had four l e v e l s : 0-25%, 25-50%. 50-75% and 75-100%. The r e s u l t s of the c o n d i t i o n measurements are not presented as they do not r e l a t e to the a n a l y s i s of movement pat t e r n s or conclusions regarding strategy e v o l u t i o n . F i s h were returned to the same s e c t i o n of stream from which they were captured and allowed to recover. S i x to eight f i s h were captured and tagged per week depending on the numbers of i n d i v i d u a l s comprising groups. Each t r i b u t a r y was walked w i t h a h i p chain and stakes were p l a c e d at 20 m i n t e r v a l s from mouth to f i r s t m i g r a t i o n b a r r i e r (see Study area). The p o s i t i o n of each f i s h was recorded once during the day and movement was monitored f o r one hour at n i g h t . Night time observations continued f o r one week, a f t e r which each f i s h was l o c a t e d only once d a i l y to provide i n f o r m a t i o n regarding l e n g t h of l i f e on the breeding grounds. Results Migration Phase II: movement prior to association with a spawning group Nine males, three. l a r g e hooknose (2-4 kg) , three intermediate hooknose (1-2 kg) and three jacks (500-700 g) were 16 captured and radio tagged during 1992 (Table 1.1). Immediately a f t e r r e l e a s e , a l l males dropped downstream. This r e a c t i o n i s b e l i e v e d to have r e s u l t e d from the a r t i f i c i a l displacement upstream (Heggberget et a l . 1988) rather than as a r e s u l t of the tagging procedure. None of the males tagged i n 1993 moved downstream. Other stud i e s show no i l l e f f e c t s of the tagging procedure used i n t h i s i n v e s t i g a t i o n (Mellas and Haynes 1985, E i l e r 1988, Webb and Hawkins 1989). One of the tagged males, a ja c k disappeared w i t h i n 48 hrs of r e l e a s e ; t h e r e f o r e , usable data were c o l l e c t e d f o r eight i n d i v i d u a l s (Table 1.1). I t q u i c k l y became evident that peaks of movement and spawning a c t i v i t y i n Kanaka Creek occurred at n i g h t . The d i u r n a l a c t i v i t y p a t t e r n f o r one s a t e l l i t e male i s presented i n Figure 1.2 (Note: dusk occurred between 1600 and 1700 hrs) as an example of the noctu r n a l behavior e x h i b i t e d by a l l tagged males. This male succumbed to pre d a t i o n three days a f t e r r e l e a s e . During the day, tagged f i s h occupied deep pools along with s e v e r a l other untagged f i s h . U s u a l l y l o c a t e d on bends, these pools were most o f t e n bordered by steep c l a y banks and/or t r i b u t a r i e s . F i s h were not observed on r i f f l e s d uring d a y l i g h t hours; but, at nigh t males moved onto r i f f l e s where s e v e r a l i n d i v i d u a l s e x h i b i t e d spawning behavior. D i f f e r e n t p atterns of movement were observed by the 17 Table 1.1 Numbers of coho males radio tagged during two years of study. Brackets s i g n i f y number of i n d i v i d u a l s omitted from a n a l y s i s as a r e s u l t of predation or s i g n a l l o s s w i t h i n 48 hours of r e l e a s e . Creek Date Status Life history strategy (Reproductive tactic) Total of run Large Hooknose Intermediate Jack Small Kanaka 7 30 Nov Nov 92 E a r l y 2 2 2 6 9 30 Dec Dec 92 Peak 1 1 1(1) 3 Total 1992 3 3 3 9 (Alpha) (Satellite) First Second (Sneak) Donovan 28 7 Nov Dec' 93 Peak 4 3 2 1 10 Thornvale 10 20 Dec Dec 93 Peak 2 2 2(1) 2(1) 8 20 26 Dec Dec 93 Interrupted 4(1) 3(1) 1 2(1) 10 1 10 Jan Jan 93 Late 4 2 0 0 6 Total 1993 14 10 5 5 34 Total 92 & 93 17 13 5 8 43 18 100 9-December 10-December aj w a) a) o u a m w •H Q 100 80 60 [• 40 • 20 • 0 100 11-December ^Movement between riffle areas • • • • * • • 100 12-December 9:36 10:48 12:00 13:12 14:24 15:36 16:48 18:00 19:12 20:24 21:36 22:48 0:00 Time (hrs) Figure 1.2 P e r i o d i c i t y of movement and a c t i v i t y f o r a s a t e l l i t e male during four consecutive days of observ a t i o n , 9 to 12 December, 1992. S o l i d l i n e s i n d i c a t e periods of continuous observation. 19 d i f f e r e n t s i z e classes of males. Large hooknose males g e n e r a l l y moved to a stream segment where they remained u n t i l death (Figure 1.3) . One l a r g e male i n i t i a l l y e x h i b i t e d e x p l o r a t o r y behavior u n t i l he entered Donovan Creek. He remained w i t h i n the same l o c a t i o n f o r one week, a f t e r which time he d i e d and was recovered. While i n the t r i b u t a r y , he was observed as the dominant male i n a spawning, group (Figure 1.4). Intermediate s i z e d hooknose males e x h i b i t e d more e x p l o r a t o r y movement. Often these males were a s s o c i a t e d with two or more d i f f e r e n t r i f f l e areas (> 100 m apart) i n a s i n g l e night (Figure 1.2 and 1.3) . A l l intermediate males d i s p l a y e d l o c a l i z e d h o r i z o n t a l movements not w e l l q u a n t i f i e d by the methods used i n t h i s study (Hawkins and Smith 1986). Jack males showed the l e a s t amount of movement. During a 24 hr p e r i o d , the greatest distance moved by l a r g e and intermediate hooknose males was 1800 m and 1700 m r e s p e c t i v e l y . Jack males moved a maximum of 500 m. Jacks were never observed a c t i v e l y moving but they, nevertheless, e x h i b i t e d a gradual, u n i d i r e c t i o n a l m i g r a t i o n p a t t e r n (Figure 1.3) . They were t y p i c a l l y found near the stream bank, i n pools or under d e b r i s . On the n i g h t of 21 November, 1992 one jack male and one l a r g e hooknose male moved i n t o Thornvale and Donovan Creeks r e s p e c t i v e l y (Figures 1.3 and 1.4). This m i g r a t i o n corresponded w i t h increased flows ( i . e . p r e c i p i t a t i o n , Figure 20 Large Hooknose -1500 J. •2000 2000 1500 1000 500 0 -500 •1000 •1500 •2000 Movement into Thornvale creek 10 12 14 16 18 20 22 Days after release F i g u r e 1.3 Movement o f male coho l i f e h i s t o r y s t r a t e g i e s p r i o r t o a s s o c i a t i o n w i t h a b r e e d i n g group, 1992. At ti m e o f c a p t u r e , males d i d not have f u l l y d e v e l o p e d s e c o n d a r y s e x u a l c h a r a c t e r i s t i c s . 21 Large Hooknose 2000 o M <H <D O C as •P to -H Q Movement i n t o Donovan Creek 0 1 2 3 4 6 7 9 10 11 12 13 14 15 16 17 18 19 20 21 22 Days after release Figure 1.4 Exploratory movements of a large hooknose male p r i o r to j o i n i n g a mating group i n November, 1992. 22 3.1 Chapter 3). Large numbers of spawning a d u l t s were l o c a t e d i n these t r i b u t a r i e s ; thus, tagging e f f o r t s i n 1993 were focused i n these Creeks. Migration Phase III: movement after association with a spawning group During 1993, a t o t a l of 14 alpha males, 15 s a t e l l i t e males and 5 jack males were captured and radio tagged wh i l e a s s o c i a t e d w i t h spawning groups (Table 1.1). As before, only those males that remained a l i v e 48 hrs a f t e r r e l e a s e were analyzed f o r movement (n = 29). The mating t a c t i c s of males are defined by t h e i r p o s i t i o n w i t h i n a group h i e r a r c h y . As expected, the l a r g e s t male i n a group was always the dominant male and the sm a l l e s t male a jack or s a t e l l i t e (Table 1.2). I n t e r e s t i n g l y , there was l i t t l e o v e r l a p i n s i z e among the hooknose males that adopted dominant or s a t e l l i t e t a c t i c s (Figure 1.5). A n a l y s i s of the fork length data c o l l e c t e d at the Kanaka Creek counting fence, revealed that the m a j o r i t y of hooknose males i n the population were i n the s a t e l l i t e s i z e group (Figure 1.5) . This was an unexpected f i n d i n g c o n s i d e r i n g that i n t e r m e d i a t e s i z e d s a t e l l i t e males are supposed to be s e l e c t e d against (Gross 1985). D i f f e r e n c e s i n the amount of movement were a l s o observed between alpha, s a t e l l i t e and jack males (Figure 1.6). The l a r g e 23 Table 1.2 Length (cm) and weight (kg) measurements of coho breeding group males captured f o r r a d i o tagging i n 1993. Largest male i n group i s always dominant. Group Date Tagged Reproductive tactic Location (m) Fork length (cm) Weight (kg) 1 28 Nov Alpha 810 62 50 2 50 1 28 Nov S a t e l l i t e 1 810 46 00 0 88 2 28 Nov Alpha 660 62 50 2 50 2 30 Nov Alpha (challanger) 660 59 70 2 30 2 30 Nov S a t e l l i t e 1 660 53 40 1 70 2 30 Nov S a t e l l i t e 2 660 58 20 1 60 3 2 Dec Alpha 760 79 50 5 20 4 3 Dec Alpha 910 55 00 1 70 4 3 Dec S a t e l l i t e 1 910 51 70 1 40 4 3 Dec S a t e l l i t e 2 910 47 80 0 95 4 5 Dec Jack 910 28 20 0 26 5 7 Dec Jack 350 27 80 0 23 6 10 Dec Alpha •310 59 40 1 90 6 10 Dec S a t e l l i t e 1 310 45 20 1 00 6 10 Dec S a t e l l i t e 2 310 45 30 0 70 6 10 Dec Jack 310 30 50 0 31 7 10 Dec Alpha 390 61 00 2 20 7 10 Dec S a t e l l i t e 1 390 49 90 1 20 7 10 Dec S a t e l l i t e 2 390 45 90 0 80 7 10 Dec Jack 390 unknown unknown 8 ' 20 Dec Alpha 355 57 00 1 80 8 20 Dec Jack 355 unknown unknown 9 20 Dec Alpha 300 53 20 1 45 9 20 Dec S a t e l l i t e 1 300 43 30 0 80 10 20 Dec Alpha 155 59 60 2 10 10 20 Dec S a t e l l i t e 1 155 50 80 1 20 10 20 Dec S a t e l l i t e 2 155 50 60 1 30 10 20 Dec Jack 155 39 20 0 60 10 20 Dec Jack 155 34 00 0 40 11 20 Dec Alpha 250 61 20 2 30 11 20 Dec S a t e l l i t e 1 250 58 00 1 80 12 2 Jan Alpha 97 62 70 2 40 12 2 Jan Alpha (challanger) 97 58 60 2 00 12 2 Jan S a t e l l i t e 1 97 49 40 1 40 12 2 Jan S a t e l l i t e 2 97 50 20 1 20 13 3 Jan Alpha 75 60 80 2 40 13 3 Jan Alpha (challanger) 75 60 00 2 40 24 I 1 Alpha E B B S a t e l l i t e • • Jack -X-1987/88 100 i 25-34 35-44 45-54 55-64 65 + Fork length (cm) F i g u r e 1.5 Length-frequency d i s t r i b u t i o n of 34 male coho captured and r a d i o tagged during the 1993 spawning run i n Kanaka Creek. Males are grouped by r e p r o d u c t i v e t a c t i c ; Alpha, S a t e l l i t e and Jack. The s o l i d l i n e represents length-frequency data c o l l e c t e d on male coho captured at the counting fence on Kanaka creek during the 1987/88 run (Murdoch 1988, n = 99). 25 Six Dominant Males 0) m m <u rH 0) M e o M *H (U 0 C n) +> 01 •rH Q Eight. S a t e l l i t e Males Two Jack Males 2000 1000 0 -1000 -2000 -3000 -4000 -5000 -6000 -7000 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Days after release F i g u r e 1.6 Movement p a t t e r n s o f male coho t h a t adopted d i f f e r e n t r e p r o d u c t i v e t a c t i c s a f t e r a s s o c i a t i o n w i t h a b r e e d i n g group. Males r e p r e s e n t i n d i v i d u a l s c a p t u r e d and t a g g e d from 28 November t o 10 December, 1993 d u r i n g t h e peak o f the spawning p e r i o d . Note open c i r c l e s on s a t e l l i t e graph r e p r e s e n t second s a t e l l i t e s , s o l i d s q uares r e p r e s e n t f i r s t s a t e l l i t e males. 26 s c a l e i n Figure 1.6 emphasizes the much greater d i s t a n c e moved by s a t e l l i t e males compared to alpha and jack males. On average, s a t e l l i t e males moved 2 to 10 times f u r t h e r i n a 24 hr p e r i o d than alpha or jack males (Figure 1.7). S a t e l l i t e males always moved greater distances than other b e h a v i o r a l types, though the magnitude of a l l migrations was a f f e c t e d by temperature and season (Figure 3.2 Chapter 3). On a smaller s c a l e , i t i s evident that alpha males were e x h i b i t i n g movement but t h e i r movements were r e s t r i c t e d to a sm a l l segment of stream (Figure 1.7). In general, alpha male movements were a s s o c i a t e d w i t h accessing a sub-set of females w i t h i n a stream. The same females were repeatedly attended by a p a r t i c u l a r alpha male, often with days between previous v i s i t s (Figure 1.8). In contrast, s a t e l l i t e movements were often a s s o c i a t e d w i t h e n t r y i n t o m u l t i p l e waterways (Figure 1.9). Seventy-five percent of s a t e l l i t e males were observed i n at l e a s t two water ways. Alpha and jack males tagged i n 1993 were never observed l e a v i n g the Creek where they were i n i t i a l l y captured. Two of the f i v e tagged jack males disappeared (predated and captured) w i t h i n 48 hours a f t e r r e l e a s e . Therefore, movement data was a v a i l a b l e f o r only three j a c k s . L i k e alpha males, tagged jack males e x h i b i t e d r e s t r i c t e d movement w i t h i n a small stream segment (Figure 1.6 and 1.7). The jack male tagged i n 27 3000 2500 •0 2000 1-t % o 1500 o a m -p •H 1000 500 Dominant. |S| i 1*1 i Pi i n i a . P i . F i r s t S a t e l l i t e I B M I W I B M I B M I M B I B B I I Second S a t e l l i t e Jack. • 1^  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Individual Males F i g u r e 1.7 Mean d a i l y distance (+/-SE) moved by male coho adopting d i f f e r e n t reproductive t a c t i c s . Males represent i n d i v i d u a l s captured and tagged from 28 November to 10 December, 1993 during the peak of the spawning p e r i o d . 28 November-Donovan December-Donovan 01 n) <U .-t tt) u 8 M <H (U 0 in •H Q January-Thornvale Days after release (m) Figure 1.8 Movement of three dominant or alpha males i n r e l a t i o n to i n d i v i d u a l females accessed. Each l e t t e r represents a p a r t i c u l a r female associated with a p a r t i c u l a r male. Figure t i t l e s i n d i c a t e month and Creek of o r i g i n a l capture. 29 November-Donovan 2000 , -3000 --4000 • -5000 --6000 --7000 -December-Donovan <D u) id IB rH IS U e o u <H d) o c m 4J CD 2000 10 00 I- / Donavin 0 -1000 -2000 -3000 -4000 -5000 -6000 -7000 Days a f t e r release Figure 1.9 Movement of three s a t e l l i t e males i n 1993. Figure t i t l e s i n d i c a t e date and Creek of o r i g i n a l capture. Each box represents a time and l o c a t i o n r e cord f o r a f i s h . Arrows i n d i c a t e movement to a new waterway. 30 Donovan Creek moved between two females that had constructed nests w i t h i n 5 m of one another f o r two days, a f t e r which he was predated upon (Figure 1.10). Jacks tagged i n Thornvale Creek also attended more than one female; however, u n l i k e the Donovan tagged jack, they were not seen r e v i s i t i n g the same female. Jacks were observed a s s o c i a t e d w i t h a breeding group on 24 separate occasions. On 14 of these occasions, the jack was found h i d i n g i n the nest w i t h the female and dominant male ra t h e r than i n a refuge outside the nest (Figure 1.11). This behavior by jack coho has not been reported before although p r e c o c i a l charr (Svedang 1992) and kokanee sockeye (Foote and L a r k i n 1988) have been reported i n the nest w i t h a much l a r g e r spawning p a i r . In the nest, jacks courted ( i . e . quivered) the female while remaining out of view of the alpha male, ( i . e . c r o s s i n g underneath the female while the alpha male crossed overtop) . On four of the t o t a l f i v e occasions where gamete re l e a s e was witnessed, a jack male was observed i n the nest immediately p r i o r to and during the spawning event. The tagged jacks observed i n the nest were the smallest i n d i v i d u a l s ( l e s s than 30 cm) . Although the sample s i z e i s too small f o r any conclusions, t h i s may mean that only small jacks are able to occupy the nest p o s i t i o n . Other refuges used by jacks i n c l u d e d woody d e b r i s , l a r g e 31 December-Donovan 150 -50 --100 --150 --200 --250 --300 L ai CO (IS <u H a) u 8 M <M <U O C n> -P (0 a December-Thornvale December-Thornvale 0 1 2 3 4 5 6 7 Days a f t e r release Figure 1.10 Movement and type of refuge used by ra d i o tagged jack males i n Donovan and Thornvale Creeks, 1993. Movement of the Donovan jack was between two redds i n clo s e p r o x i m i t y . Movements of the Thornvale ja c k s were a s s o c i a t e d w i t h accessing new females. 32 Positions Utilized by Jack Males i n Breeding Groups (n = 24). Figure 1.11 Frequency of refuge u t i l i z a t i o n by jac k s i n Donovan and Thornvale Creeks. ! 33 cobbles and boulders, and undercut banks. These refuges were located adjacent to or s l i g h t l y downstream from a n e s t i n g p a i r . On one occasion, a dominant male was observed charging the woody debris adjacent to the nest, though he was unsuccessful at di s l o d g i n g the two jacks w i t h i n . In those instances where jacks were observed at the t a i l end of a h i e r a r c h y ( i . e . s a t e l l i t e p o s i t i o n ) , cover was u s u a l l y l a c k i n g . Discussion R e s u l t s of t h i s i n v e s t i g a t i o n show that i n Kanaka Creek male coho movement and spawning a c t i v i t y occurs p r i m a r i l y at night and that movement patterns are t a c t i c s p e c i f i c . Dominant hooknose males remained w i t h i n a r e s t r i c t e d stream segment, a c c e s s i n g the females that b u i l d nests w i t h i n the segment. S a t e l l i t e hooknose males moved both f r e q u e n t l y and e x t e n s i v e l y , often entering several d i f f e r e n t waterways during t h e i r breeding l i f e s p a n . Jack males were found to reside i n a small segment of stream throughout t h e i r breeding l i f e s p a n and made use of a v a r i e t y of refuges, i n c l u d i n g the nest i t s e l f , from which to 'sneak' f e r t i l i z a t i o n s . The observations of nocturnal a c t i v i t y and movement i n t h i s study appear to c o n t r a d i c t the conventional wisdom of d i u r n a l spawning migrations f o r coho salmon (Sandercock 1991); however, t h i s c o n t r a d i c t i o n r e s u l t s p r i m a r i l y from a l a c k of d i s t i n c t i o n 34 between the three phases of movement. E a r l y work on coho movement o f f e r e d c o n f l i c t i n g o p i n i o n s . Many i n v e s t i g a t o r s reported that coho migrate upstream during d a y l i g h t hours (Neave 1943, Briggs 1953, Br e t t and MacKinnon 1954, Shapovalov and Taft 1954, E l l i s 1962, Fraser et a l . 1983) although E l l i s (1962) noted that the numbers of coho migrants increased ( i . e . peak) as t h e i r observations ended (dusk) and suggested t h a t the increase "probably continued a f t e r the r o u t i n e counts had stopped". These s t u d i e s focused on the f i r s t phase of freshwater migration, namely entry i n t o freshwater. In c o n t r a s t , an e a r l y study conducted at the entrance of spawning t r i b u t a r i e s ( i . e . Phase I I of migration) , found that coho entered the fishway mostly at night ( A l l e n 1956). Nocturnal migrations of salmonids i n t r i b u t a r y streams have been documented f o r A t l a n t i c salmon (Hawkins and Smith 1986, Webb and Hawkins 1989, Webb 1989, Webb 1990) and b u l l t r o u t (Fraley and Shepard 1989) . Counts of coho through the fishway on Kanaka Creek a l s o i n d i c a t e peak migrations occur at ni g h t (pers. comm. John Heaven; manager of Kanaka Creek B e l l I r v i n g Hatchery). Therefore, a s h i f t from day to ni g h t i n the tim i n g of coho spawning migrations appears to occur a f t e r the f i s h have entered freshwater, but before they reach the spawning beds. I t has been suggested, that sustained movement e a r l y on r e f l e c t s the f i n a l stage of the marine behavior of the adult salmon (Webb 1992). 35 N o c t u r n a l behavior may r e s u l t from the r i s k of p r e d a t i o n . The i n f l u e n c e of predation i s p o o r l y understood, though i t i s l i k e l y to have i n c r e a s i n g importance f o r species (such as coho) t h a t spawn i n shallow waters and have long breeding l i f e spans (van den Burge and Gross 1986). Avoidance of predators may be accomplished by r e s t r i c t i n g a c t i v i t y s p a t i a l l y , to deep pools and areas with vegetative cover (Hoopes 1972) and temporally, to periods of darkness. Whereas no daytime spawning a c t i v i t y was observed i n Kanaka Creek i n 1992, when observations were confined to the shallow t r i b u t a r i e s (Thornvale and Donovan Creeks) i n 1993, spawning occurred throughout the day. Both t r i b u t a r i e s lacked the daytime refuges ( i . e . deep pools) a v a i l a b l e i n the mainstem of Kanaka Creek, though Donovan Creek d i d o f f e r some pool h a b i t a t . More daytime spawners were observed i n Thornvale, the shallowest and most narrow t r i b u t a r y (Table 3.1), than i n Donovan Creek and more daytime spawning was observed i n Donovan than i n Kanaka, suggesting that the incidence of daytime spawning, may be determined by the h a b i t a t (Webb 1992). The patterns of movement by male coho adopting a l t e r n a t i v e r eproductive t a c t i c s correspond to the three a c t i v i t y p a tterns described f o r breeding A t l a n t i c salmon (Webb and Hawkins 1989). Dominant hooknose coho males r e s t r i c t e d t h e i r movements to a s m a l l segment of stream. This i s c o n s i s t e n t w i t h Webb and Hawkins (1989) conclusion that a long stay i n a small segment of 36 stream i s i n d i c a t i v e of spawning success. Furthermore, Webb and Hawkins (1989) noted that s u c c e s s f u l A t l a n t i c males moved from female to female w i t h i n t h e i r r e s t r i c t e d stream segment, which was also the pattern of behavior observed among coho alpha males. S a t e l l i t e coho males d i s p l a y e d the second type of movement p a t t e r n described by Webb and Hawkins (1989) f o r male A t l a n t i c salmon, moving e x t e n s i v e l y between spawning areas. Schroder's (1981) p r e d i c t i o n that small or weak males would move ext e n s i v e l y was also confirmed by the r e s u l t s . However, i n t h i s i n v e s t i g a t i o n , a l l s a t e l l i t e males, regardl e s s of the number of dominant males, e x h i b i t e d frequent and extensive m i g r a t i o n s . Unlike A t l a n t i c g r i l s e males, jack coho males d i d not move ext e n s i v e l y between main spawning areas (Webb and Hawkins 1989). The l a c k of movement e x h i b i t e d by jack males i s l i k e l y a r e f l e c t i o n of t h e i r r e s t r i c t e d energy reserves r a t h e r than the a v a i l a b i l i t y of ^ s u i t a b l e ' d e b r i s refuges as p r e v i o u s l y suggested (Gross 1991), since jacks were most f r e q u e n t l y observed i n the nest (Figure 1.11). Nest u t i l i z a t i o n may be p a r t i c u l a r l y b e n e f i c i a l to mainstem spawning jacks where debris refuges are l i m i t e d to the banks (by the high flows during the coho spawning period) and where spawning p a i r s are o f t e n l o c a t e d mid channel. The information gathered on jack and hooknose reproductive t a c t i c s challenges much of the current model proposed f o r male 37 coho reproductive s t r a t e g i e s . F i r s t , i f p r o x i m i t y to the female i s a r e l i a b l e p r e d i c t o r of f e r t i l i z a t i o n success (Gross 1985), then f i n d i n g jacks d i r e c t l y under the p a i r suggests higher f e r t i l i z a t i o n success than p r e v i o u s l y described. While, jack males i n the nest may r i s k severe i n j u r y from l a r g e r hooknose males and thereby reduce breeding o p p o r t u n i t i e s , i n f o r m a t i o n gathered on competitive i n t e r a c t i o n s among males of breeding groups does not support t h i s hypothesis (Chapter 2). Second, the high degree of asymmetry ( d i f f e r e n c e i n size) observed among hooknose males ( s a t e l l i t e s and dominants) i s not c o n s i s t e n t w i t h the idea that a l l hooknose males adopt a f i g h t i n g t a c t i c . I f d i s r u p t i v e s e l e c t i o n operates to e l i m i n a t e intermediate s i z e d males from the population as they are n e i t h e r e f f e c t i v e f i g h t e r s nor sneakers (Gross 1985), then the m a j o r i t y of hooknose males should be c l o s e l y matched i n s i z e . However, measurements of hooknose males revealed two d i s t i n c t phenotypes ( s i z e c lasses) corresponding to dominant and s a t e l l i t e r e p r o d u c t i v e t a c t i c s . This observation suggests that the two t a c t i c s are not interchangeable. Furthermore, h i s t o r i c a l data i n d i c a t i n g the abundance of intermediate s i z e d males w i t h i n the Kanaka Creek coho p o p u l a t i o n (Murdoch 1988) suggests that s a t e l l i t e , i s a s u c c e s s f u l t a c t i c . The hooknose str a t e g y has p r e v i o u s l y been considered as a pure s t r a t e g y i n which males compete f o r access to females and i n which intermediate s i z e d males are s e l e c t e d against (Gross 38 1985). I f the s a t e l l i t e t a c t i c i s s u c c e s s f u l , then i t may be expected that there i s a high cost a s s o c i a t e d w i t h dominance as s a t e l l i t e males i n v e s t more energy i n movement than dominant males yet are b e l i e v e d to achieve fewer f e r t i l i z a t i o n per spawning event. One obvious cost of dominance i s i n t r a - s e x u a l c o m p e t i t i o n and i s the focus of the next chapter. In summary, the evidence gathered during i n v e s t i g a t i o n s of instream patterns of movement suggests that, the evol u t i o n and maintenance of male mating s t r a t e g i e s i n coho populations i s more complex than p r e v i o u s l y described. 39 CHAPTER II COMPETITIVE INTERACTIONS BETWEEN MALE COHO ON THE SPAWNING GROUNDS Introduction Models that address the e v o l u t i o n and maintenance of reproductive s t r a t e g i e s , require estimates of t a c t i c f i t n e s s f o r comparison. Consequently, the reproductive costs and b e n e f i t s associated with a l t e r n a t i v e t a c t i c s has been the subject of much re s e a r c h . In P a c i f i c salmon, i n t r a - s e x u a l competition, a cost of r e p r o d u c t i o n , has been proposed to account f o r spawner d i s t r i b u t i o n s (Schroder 1973, Schroder 1981, Sargent et a l . 1986), sexual dimorphism (Quinn e t . a l . 1995, Quinn and Foote 1994), le n g t h of l i f e on the breeding grounds (van den Berghe and Gross 1986), breeding success and u l t i m a t e l y , the e v o l u t i o n of r e p r o d u c t i v e t a c t i c s (Gross 1984, Gross 1985, Fleming and Gross 1989, Gross 1991, Fleming and Gross 1994). In salmon, frequently more than one male attends a spawning female. The c o l l e c t i o n of a female and attendant males form a spawning group. E a r l y i n v e s t i g a t i o n s of male salmonid competition describe a v a r i e t y of d i s p l a y s and aggressive i n t e r a c t i o n s that males use to e s t a b l i s h dominance (Hanson and Smith 1967, Schroder 1973) . A dominant male must defend the female from both non-group (intruder) and group ( s a t e l l i t e ) c h a l l e n g e r s . Although the process of group formation has not 40 been documented, hooknose males ( i . e . dominant and s a t e l l i t e males) are b e l i e v e d to gain access to matings through f i g h t i n g (Gross 1984, Gross 1985, Hutchings and Myers 1988, Keenlyside and Dupuis 1988). Studies of the s o c i a l r e l a t i o n s h i p s among pink salmon males i n a mating group i n d i c a t e l i t t l e overt competition among group members, i n c l u d i n g those groups w i t h l i t t l e d i f f e r e n c e i n s i z e among i n d i v i d u a l s (Chebanov 1980, Keenlyside and Dupuis 1988). In general, dominant males d i r e c t much more aggression at non-group members (small and large) than group members (Keenlyside and Dupuis 1988). However, when spawning i s imminent ( i . e . w i t h i n 15 minutes), sub-dominant males crowd the nest and dominant aggression to group members increases (Keenlyside and Dupuis 1988). The o b j e c t i v e of t h i s i n v e s t i g a t i o n was to provide a q u a n t i t a t i v e d e s c r i p t i o n of the breeding behavior of male coho by q u a n t i f y i n g male competitive i n t e r a c t i o n s i n r e l a t i o n to mating t a c t i c s and breeding groups. A secondary o b j e c t i v e was to use the q u a n t i t a t i v e data c o l l e c t e d to speculate about costs of r e production f o r d i f f e r e n t c l a s s e s of males. Dominant alpha males were expected to have a high number of i n t e r a c t i o n s w i t h other males as they remained w i t h i n a r e s t r i c t e d stream segment, competing f o r access to females and are p r i m a r i l y concerned w i t h excluding other males from access to the female (Chapter. 1). Because movement and competition 41 reduces energy reserves, s a t e l l i t e males were expected to have fewer competitive i n t e r a c t i o n s than alpha males as they showed frequent and extensive movements (Chapter 1). Jack males were expected to have few aggressive i n t e r a c t i o n s w i t h hooknose males as they were hidden i n refuges, l i m i t e d by energy reserves and would l i k e l y s u f f e r s e r i o u s i n j u r y i f attacked. However, jack males were expected to compete among themselves f o r refuges (Gross 1985). The competitive investments of males were f u r t h e r expected to r e f l e c t f e r t i l i z a t i o n success. Measures of s a t e l l i t e male f e r t i l i z a t i o n success (determined using e l e c t r o p h o r e t i c techniques) i n d i c a t e that on average, a s a t e l l i t e male sockeye salmon; Oncorhynchus nerka f e r t i l i z e s 10% (range: 1.6% 47.7%) (Chebanov et a l . 1983) and a chum salmon; Oncorhynchus keta 25.5% (range: 0% - 46%) (Schroder 1981) of the eggs. In contrast, an alpha sockeye male f e r t i l i z e s 90% (Chebanov et a l . 1983) and alpha chum male 63% (range: 53% - 100%) (Schroder 1981) of the eggs. Thus, alpha males were expected to be w i l l i n g to f i g h t harder to o b t a i n t h e i r r e l a t i v e l y l a r g e r reproductive payoff. E s c a l a t e d contests between alpha males were expected to occur as the payoff (63%-90% f e r t i l i z a t i o n success) of the p o s i t i o n i s high. S i m i l a r l y , each s a t e l l i t e hooknose male i n the mating group was p r e d i c t e d to have the most i n t e r a c t i o n s 42 w i t h the male j u s t above i t i n the h i e r a r c h y i f f e r t i l i z a t i o n success increases w i t h p r o x i m i t y to the female as has been argued (Gross 1985). I t was hypothesized that group aggression l e v e l s may be explained by the number of males i n a group (Quinn et a l . 1995) . Larger groups were expected to demonstrate higher l e v e l s of aggression ( i n t e r a c t i o n s / 1 0 min) because there are more combatant p a i r s (combinations of males) c o n t r i b u t i n g to the groups t o t a l i n t e r a c t i o n s . Because males have been found to direct,much more aggression at non-group members (Keenlyside and Dupuis 1988), the presence of i n t r u d i n g males ( i . e . non-group males) was expected to increase l e v e l s of group aggression. Methods A t r a i l was constructed along Donovan and Thornvale Creeks, t r i b u t a r i e s of Kanaka Creek (Figure 1.1). Each t r i b u t a r y was walked with a hip chain and stakes were placed at 20 m i n t e r v a l s from the Creek mouth to the f i r s t m i g r a t i o n b a r r i e r (Study area). During the f i r s t n ight of each week from 28 Nov 1993 to 6 Jan 1994, a Creek was walked i n search of mating groups. A mating group was define d as the a s s o c i a t i o n of d i f f e r e n t i n d i v i d u a l males and a female i n a breeding assemblage at the time of observation. Upon l o c a t i n g a mating group, i t s Creek l o c a t i o n (m) , number of males, t a c t i c of each male, and aggressive i n t e r a c t i o n s among males were recorded. Each group 43 was monitored f o r 10 minutes p r i o r to r e c o r d i n g aggressive i n t e r a c t i o n s to c l e a r l y i d e n t i f y members and t h e i r p o s i t i o n w i t h i n the group h i e r a r c h y . In coho, the membership of mating groups changed f r e q u e n t l y ; however, since the time spent obs e r v i n g a group was predetermined, i t was not p o s s i b l e to comment on how long each group p e r s i s t e d . I n t e r a c t i o n s w i t h i n the group were recorded during ten minute observation p e r i o d s . I f a male l e f t the group during an observation period then the observation period was excluded from a n a l y s i s . Providing the group remained i n t a c t , three ten minute observation periods, each separated by 5 minute i n t e r v a l s , were c o l l e c t e d f o r each breeding group wi t h the a i d of a Dictaphone. Tapes were l a t e r t r a n s c r i b e d d e t a i l i n g the frequency of aggressive i n t e r a c t i o n s between males of d i f f e r e n t reproductive t a c t i c s w i t h i n breeding groups. A score of 1 was assigned to each aggressive i n t e r a c t i o n i n which a male was engaged ( e i t h e r r e c e i v i n g or d e l i v e r i n g the b e h a v i o r ) . I f a male f a i l e d to i n t e r a c t w i t h other members of the group, a score of 0 was assigned. A g o n i s t i c male behaviors t h a t were scored i n c l u d e d d o r s a l and l a t e r a l d i s p l a y s , digs, c r o s s i n g over, charges, chases and b i t e s (Table 2.1). While most of the d i s p l a y s f o r coho are s i m i l a r to those described f o r chum salmon (Schroder 1973), the cross d i s p l a y was unique. P r i o r to crossing over the caudal peduncle of another male, 44 Table 2.1 A g o n i s t i c behaviors observed and scored f o r male coho. Displays D o r s a l : U s u a l l y performed by two males, f i s h remain p a r a l l e l with d o r s a l f i n s , and u s u a l l y p e c t o r a l f i n s , extended. Opponents may charge or cross-over. Attacks Chase: One male pursues another (of short or long d u r a t i o n 1-5 sees). L a t e r a l : One male swims upstream, turns perpendicular to opponent and presents l a t e r a l side (often i n combination with erect f i n s ) . Opponent may remain motionless. Charge: An open mouthed rush that r e s u l t s i n contact with opponents body; normally preceeded by a d o r s a l or l a t e r a l d i s p l a y . Dig: Male turns (at l e a s t 45°) on l a t e r a l side and undulates caudal f i n thereby d i s p l a c i n g substrate. Digging normally occurs outside of the nest. B i t e : A t t a c k i n g male b i t e s an opponents body; d i r e c t e d at caudal and d o r s a l f i n s , d o r s a l hump, and head. Cross: One male r i s e s out of water and crosses over opponents body, to the opposite s i d e . P r i o r to cross-over i n i t i a t i n g male may place h i s lower jaw i n f r o n t of h i s opponents extended d o r s a l f i n and d e l i b e r a t e l y sweep his jaw along the d o r s a l ridge, f l a t t e n i n g the f i n . 45 one male would r i s e from the water, place h i s lower jaw i n f r o n t of h i s opponents erect d o r s a l f i n , and d e l i b e r a t e l y sweep h i s jaw (2-4 times) back and f o r t h along the d o r s a l r i d g e , f l a t t e n i n g the f i n . This ^rubbing' behavior p r i o r to c r o s s i n g over d i d not occur between sexes during c o u r t s h i p . A f t e r having scored male competitive i n t e r a c t i o n s , group members were captured and tagged (Chapter 1). Group capture and tagging was done at the beginning of each week though jack males were captured o p p o r t u n i s t i c a l l y . Tagged males were l o c a t e d twice d a i l y (once during the day, once during the n i g h t ) , f o r the d u r a t i o n of the week and a d d i t i o n a l sets of competitive observations were recorded. Nighttime observations were made p o s s i b l e by r e f l e c t i n g incandescent l i g h t on the stream bank downstream of the group, so that the edges of i l l u m i n a t i o n f e l l upon group members. Data Analysis As a r e s u l t of the mobile nature of males (Chapter 1), observations of i n t e r a c t i o n s made on tagged males the day a f t e r t a g g i n g were l i k e l y to i n v o l v e groups i n which not a l l males were tagged. Consequently, competitive i n t e r a c t i o n s were scored f o r both tagged and non-tagged breeding group members. This presented a challenge i n d e f i n i n g an independent observation. For example, consider the case of a male f i r s t i d e n t i f i e d and tagged on day 1 of the sampling p e r i o d i n Donovan Creek as 46 the f i r s t s a t e l l i t e of group A. On day 2, the same male was t r a c k e d to Thornvale Creek where he was observed as f i r s t s a t e l l i t e i n another mating group i n which the female and a l l other males were d i f f e r e n t i n d i v i d u a l s (group B). Admittedly group A i s not completely independent of group B as the same i n d i v i d u a l belongs to both groups. However, because c o m p e t i t i v e i n t e r a c t i o n s f o r each group and p o s i t i o n s w i t h i n those groups are determined by the collection of males, I have de f i n e d an independent observation according to the unique combination of i n d i v i d u a l males. In other words, f o r the purpose of a n a l y s i s , group A and group B are each t r e a t e d as independent observations. Table 2.2 presents the number of" groups or independent observations used to c a l c u l a t e the s t a t i s t i c s presented w i t h i n t h i s chapter (Note: ab b r e v i a t i o n s f o r male t a c t i c s are a l s o defined i n Table 2.2). In t o t a l , 62 groups were observed. A l l 62 groups had an alpha male, 48 of the 62 groups had a f i r s t s a t e l l i t e male, 19 of the 62 groups had a second s a t e l l i t e e t c . . . (Table 2.2). In 35 of the 62 groups, the alpha male was a tagged male (Table 2.2). Since only fourteen individual alpha males were tagged (Table 2.2), some i n d i v i d u a l s are present i n more than one group. S i m i l a r l y , i n 19 of the 48 groups containing a f i r s t s a t e l l i t e male, the f i r s t s a t e l l i t e male was a tagged male. Since only eight individual f i r s t s a t e l l i t e 47 Table 2.2 Numbers of observations d i f f e r e n t reproductive t a c t i c s i n t e r a c t i o n a n a l y s i s . on groups of males adopting used i n competitive Reproductive Alpha F i r s t Second Third Jack Tactic S a t e l l i t e S a t e l l i t e S a t e l l i t e A b b r e v i a t i o n A SI S2 S3 J T o t a l Number of Groups 62 48 19 2 19 Number of Groups w i t h Tagged Male 35 19 5 0 8 Number of Tagged I n d i v i d u a l s 14 8 5 0 2 48 males were tagged (Table 2.2), some i n d i v i d u a l s are present i n more than one group. Having defined a u n i t of observation, the next challenge i n the a n a l y s i s was presented by the nature of the data i t s e l f . Counts of aggressive i n t e r a c t i o n s do not f i t any standard p r o b a b i l i t y d i s t r i b u t i o n making the appropriate t r a n s f o r m a t i o n u n c e r t a i n . For example, a group may have no aggressive i n t e r a c t i o n s f o r two observation periods then during the t h i r d , a l a r g e i n t r u d i n g male challenges the r e s i d e n t alpha male f o r dominance r e s u l t i n g i n a dramatic increase i n group aggression l e v e l s . In a d d i t i o n , there are large d i f f e r e n c e s i n sample s i z e s as some group types and h i e r a r c h a l p o s i t i o n s were more common than o t h e r s . For example, there i s some evidence that as time to spawning approaches, more sub-dominant males j o i n the group. These d i s t a n t sub-dominant males (e.g. t h i r d s a t e l l i t e s ) may be present f o r only a f r a c t i o n of the t o t a l time r e q u i r e d f o r the female to construct a nest and spawn. Conversely, an alpha male i s present from the groups i n c e p t i o n ( i . e . female a r r i v i n g on the spawning grounds). Consequently, there are many more observations on alpha and f i r s t s a t e l l i t e males than on second and t h i r d s a t e l l i t e males. Since group aggression l e v e l s do not f i t a normal d i s t r i b u t i o n and the variances are heterogeneous, non-parametric 49 a n a l y s i s were chosen to t e s t hypotheses concerning d i f f e r e n c e s among t a c t i c s and group s i z e s (Zar 1984). D e s c r i p t i v e summaries of the data and the counts of aggressive i n t e r a c t i o n s are presented i n conjunction w i t h a l l analyses to i l l u s t r a t e d i f f e r e n c e s between cate g o r i e s of males and groups not e a s i l y t e s t e d w i t h s t a t i s t i c s ( i . e . s i n g l e degree of freedom comparisons. Means and standard errors (SE) of a g o n i s t i c behavior scores fo r tagged males w i t h i n a reproductive t a c t i c (alpha, s a t e l l i t e and j a c k ) , were c a l c u l a t e d to determine i f the observed di f f e r e n c e s i n t a c t i c movement patterns (Chapter 1) corresponded with d i f f e r e n c e s i n aggression l e v e l s . Aggressive i n t e r a c t i o n s f o r each tagged male w i t h i n a group were averaged to ob t a i n a r a t e of i n t e r a c t i o n / 1 0 minutes. The rat e s of i n t e r a c t i o n / 1 0 minutes were then used to c a l c u l a t e the mean and SE f o r tagged males belonging to a reproductive t a c t i c . The analyses was then expanded to i n c l u d e a l l males observed (tagged and non-tagged). Again, r a t e s of i n t e r a c t i o n /10 minutes were f i r s t c a l c u l a t e d f o r males i n each of the 62 groups and then used to determine the mean and SE f o r males d i s p l a y i n g d i f f e r e n t reproductive t a c t i c s . The rat e s of i n t e r a c t i o n f o r male t a c t i c s were al s o ranked and a K r u s k a l l -W a l l i s t e s t procedure performed to determine i f aggression l e v e l s d i f f e r e d across reproductive t a c t i c s . F i n a l l y , the 50 d i s t r i b u t i o n of aggressive encounters f o r each male t a c t i c was f u r t h e r examined i n r e l a t i o n to the males opponent. Group rates of i n t e r a c t i o n /10 minutes were al s o determined for each of the 62 groups and used to c a l c u l a t e the mean and SE f o r group types that were defined according to the number of males. To t e s t the hypothesis that aggression i s i n f l u e n c e d by group s i z e , the rates of competitive i n t e r a c t i o n s f o r each of the 62 groups were ranked ( K r u s k a l l - W a l l i s ) and compared across group types. I n t e r a c t i o n s w i t h non-group males or i n t r u d e r s were then removed to examine within group aggression l e v e l s . Again, rates of interaction/10 minutes were c a l c u l a t e d f o r each group, ranked, and compared across group types by ANOVA ( K r u s k a l l - W a l l i s ) . I t was hypothesized that group aggression l e v e l s may be explained by p a i r s of combatants. P a i r s of combatants are determined by the number of males i n a group. For example, an A- S l (see Table 2.2 f o r male t a c t i c a bbreviations) group has on l y one p a i r of combatant males, the dominant male and the f i r s t s a t e l l i t e , while an A - S l - J group has three p a i r s of combatants, A - S l , A-J, and S I - J . The number of combatant p a i r s which comprise groups from 2-5 males i s : 2 males-1 combatant p a i r , 3 males-3 combatant p a i r s , 4 males-6 combatant p a i r s and 5 males-10 combatant p a i r s . The r a t e s of aggressive i n t e r a c t i o n s f o r each group, were 51 made a f u n c t i o n of the number of combatant p a i r s w i t h i n that p a r t i c u l a r group type. Each group's r a t e of i n t e r a c t i o n / 1 0 minutes was d i v i d e d by the number of combatant p a i r s i n that p a r t i c u l a r group type. The adjusted rates of competitive i n t e r a c t i o n s f o r each of the 62 groups were ranked ( K r u s k a l l - W a l l i s ) and compared across group types by ANOVA. Results Rates of aggressive interactions for males adopting alternative reproductive tactics Rates of male aggressive i n t e r a c t i o n s were found to d i f f e r s i g n i f i c a n t l y among reproductive t a c t i c s ( K r u s k a l - W a l l i s ; P < 0.001) (Table 2.3). Alpha males (both tagged and non-tagged) had much higher r a t e s of i n t e r a c t i o n (mean 15.2 SE 2.9 int / 1 0 min) than any other male t a c t i c (Figure 2.1). S i m i l a r l y , r a d i o tagged alpha males (n = 14) had the highest r a t e of aggressive i n t e r a c t i o n s (mean 9.3 SE 2.9 int/10 min) compared w i t h other tagged males belonging to d i f f e r e n t r eproductive t a c t i c s (Table 2.4) . The majo r i t y (85%) of alpha male i n t e r a c t i o n s occurred w i t h non-group males (Figure 2.2) and r e f l e c t the e s c a l a t e d contests that often occurred between la r g e males. Previous work on pink salmon s o c i a l r e l a t i o n s h i p s a l s o found males to have a s i g n i f i c a n t p o r t i o n of t h e i r i n t e r a c t i o n s with non-group members (Keenlyside and Dupuis 1988) . 52 Table 2.3 Competitive i n t e r a c t i o n s of male coho adopting a l t e r n a t i v e reproductive t a c t i c s . Rates of male competitive i n t e r a c t i o n s d i f f e r across reproductive t a c t i c s (P < 0.001) by K r u s k a l l - W a l l i s ANOVA. Reproductive Tactic A SI S2 S3 J No. o f I n t e r a c t i o n s 2291 446 227 1 92 No. of 10 minute O b s e r v a t i o n P e r i o d s 145 110 45 6 42 No. o f Groups 62 48 19 2 19 Rate of Interaction Mean/10 min (SE) 15.2 (2.9) 4.7 (0.9) 5.7 (1.3) 0.2 2 .4 (0.9) 53 20 15 10 A l p h a T F i r s t S a t e l l i t e I •'.-V •/////// v/v .-• y s s Second S a t e l l i t e T h i r d S a t e l l i t e T if m Jack Reproductive Tactic Figure 2.1 Mean rates of aggressive i n t e r a c t i o n s (+/-SE) f o r male coho adopting a l t e r n a t i v e reproductive t a c t i c s . Rates of aggression d i f f e r s i g n i f i c a n t l y among t a c t i c s ( P < 0.001) . 54 Table 2.4 Competitive i n t e r a c t i o n s of r a d i o Mean rates of i n t e r a c t i o n per 10 minutes a l t e r n a t i v e reproductive t a c t i c s . tagged coho males, for males adopting Reproductive Tactic A SI S2 J No. of Intera c t i o n s 893 216 76 25 No. of 10 minute Observation Periods 96 44 18 17 No. of Groups 35 19 5 8 Rate of Interaction Mean/10 min (SE) 9.3 (2.9) 5.5 (1.2) 4.5 (1.5) 1.8 (0.7) 55 Alpha Alpha F i r s t S a t e l l i t e Second S a t e l l i t e T h i r d S a t e l l i t e * 0 n & § a H 01 a 100 90 80 70 60 50 40 30 20 10 0 Second S a t e l l i t e Alpha mm F i r s t S a t e l l i t e Second S a t e l l i t e T h i r d S a t e l l i t e Jack • Jack -mm TIINl wmw . Intruder Alpha F i r s t S a t e l l i t e Second T h i r d S a t e l l i t e Jack S a t e l l i t e Males Within Breeding Groups F i g u r e 2.2 Frequency of competitive i n t e r a c t i o n s among males adopting a l t e r n a t i v e reproductive t a c t i c s . Note alpha and ja c k males i n t e r a c t e d p r i m a r i l y w i t h i n t r u d i n g males and s a t e l l i t e males w i t h the alpha male. 56 In t o t a l , 33 contests (in the presence of a female) between an alpha male and a large i n t r u d e r were observed w i t h the number of i n t e r a c t i o n s ranging from 2 to 285. Gener a l l y , these contests began wi t h the i n t r u d i n g male approaching the breeding group from downstream. Often, the i n t r u d e r would remain s t a t i o n a r y ( i . e . e x h i b i t s a t e l l i t e behavior) f o r a b r i e f p e r i o d before challenging the alpha male. Any s a t e l l i t e males present would f a l l downstream s l i g h t l y or move o f f to one side where they would wait and watch the ensuing b a t t l e before reassuming t h e i r p o s i t i o n . Upon the a r r i v a l of another la r g e male, the alpha male would immediately extend h i s f i n s i n a dorsal d i s p l a y (see Table 2.1 f o r d e s c r i p t i o n of a g o n i s t i c behaviors) and move away from the female, towards the i n t e r l o p e r . At t h i s p o i n t , the i n t r u d e r was e i t h e r chased from the nest area or remained to contest the alpha's dominance. I f the int r u d e r remained, the two combatants would engage i n a s e r i e s of d o r s a l d i s p l a y s and charges. Any chases recorded during t h i s attack phase of the contest were of short d u r a t i o n (approx. 1 sec.) and r e s u l t e d from one male moving away from an attempted charge. Very few b i t e s and no l a t e r a l d i s p l a y s were observed between competing l a r g e males. I f the contest continued to e s c a l a t e , ( i . e . the i n t r u d e r d i d not leave a f t e r s e v e r a l a t t a c k s ) , then the two males would begin a s e r i e s of d i s p l a y behaviors before resuming the attack 57 phase of the contest. I t was during the d i s p l a y phase of e s c a l a t e d contests that the d o r s a l rubbing and cross behaviors were observed. The contest continued w i t h a l t e r n a t i n g attack and d i s p l a y phases u n t i l one male was chased from the area completely. Of the 27 contests with known outcomes between l a r g e males, s i x r e s u l t e d i n alpha take-overs. Three of the takeovers occurred over the same female during one set of observations ( i . e . three ten minute periods) . In another two of the takeovers, the winner was observed s u c c e s s f u l l y spawning ( i . e . p a r t i c i p a t i n g as alpha male i n gamete r e l e a s e ) , one 20 minutes a f t e r the takeover, and the other, the next day. S u r p r i s i n g l y , none of the contests r e s u l t e d i n the l o s e r adopting a subordinate p o s i t i o n . Alpha males c o n t i n u a l l y d i r e c t e d aggression to any s i m i l a r s i z e d male ( i n c l u d i n g o l d and weak males) that came i n to the v i c i n i t y of the nest and breeding group, even i f the i n t r u d e r d i d not d i r e c t l y challenge but attempted to take a s a t e l l i t e p o s i t i o n . Only one r a d i o tagged alpha male was ever observed to act as a s a t e l l i t e ; however, f o r most of the observations, the alpha male was engaged w i t h other l a r g e i n t r u d i n g males. Contests between l a r g e males r e s u l t e d i n the l o s e r moving on i n search of an a v a i l a b l e female r a t h e r than occupying a sub dominant p o s i t i o n w i t h i n the hierarchy. However, e s t a b l i s h e d alpha males confined 58 t h e i r search to a r e s t r i c t e d stream segment (Chapter 1). F i r s t s a t e l l i t e males had a lower r a t e of i n t e r a c t i o n (4.7 int/10 min) than alpha males (15.2 int/10 min); but, appeared to have a higher r a t e of i n t e r a c t i o n than jack males (Table 2.3)(Figure 2.1). S i m i l a r l y , radio tagged f i r s t s a t e l l i t e males (n = 8) had a lower r a t e of aggressive i n t e r a c t i o n s (mean 5.5 i n t / 1 0 min) compared to tagged alpha males (9.3 int/10 min)(Table 2.4). While the m a j o r i t y (51 %) of f i r s t s a t e l l i t e i n t e r a c t i o n s occurred with the alpha male (Figure 2.2) they d i d not appear to r e s u l t from d i r e c t challenges to the alpha males dominance. Even when alpha males l e f t the female (exploratory movement), and the f i r s t s a t e l l i t e male assumed the dominant p o s i t i o n , next to the female, the s a t e l l i t e male r e l i n q u i s h e d the nest p o s i t i o n w i t h l i t t l e i n t e r a c t i o n upon the alpha males r e t u r n . Often w i t h i n breeding groups, alpha males and f i r s t s a t e l l i t e s were observed engaged i n a modified d o r s a l d i s p l a y . Alpha males would extend t h e i r f i n s i n a d o r s a l d i s p l a y while d r i f t i n g downstream, away from the female; however, r a t h e r than holding t h e i r p o s i t i o n and remaining p a r a l l e l as l a r g e i n t r u d e r males would respond, s a t e l l i t e males a l s o d r i f t e d downstream, ma i n t a i n i n g t h e i r h i e r a r c h i c a l p o s i t i o n s and d i s t a n c e from the alpha male. Male d i g s , though infr e q u e n t , were observed only between the alpha and f i r s t s a t e l l i t e males. In a l l instances 59 where male digging behavior was observed, the alpha male was the one that performed the behavior. F i r s t s a t e l l i t e males had t h e i r second highest number of i n t e r a c t i o n s (29%) w i t h i n t r u d e r males (Figure 2.2). However, these i n t e r a c t i o n s occurred p r i m a r i l y w i t h i n t r u d i n g s a t e l l i t e s i z e d males r a t h e r than w i t h i n t r u d i n g alpha s i z e d males. On average, contests f o r f i r s t s a t e l l i t e p o s i t i o n were re s o l v e d w i t h fewer i n t e r a c t i o n s (1.2 i n t e r a c t i o n s / 1 0 min) than alpha male i n t r u d e r contests (13.4 i n t e r a c t i o n s / 1 0 min) though the types of i n t e r a c t i o n s (attack and d i s p l a y phases) were s i m i l a r . The highest number of i n t e r a c t i o n s recorded between a f i r s t s a t e l l i t e male and s a t e l l i t e i n t r u d e r was 26 which i s reduced compared with the maximum 285 i n t e r a c t i o n s recorded between two competing alpha males. With one exception, tagged s a t e l l i t e males a l s o maintained t h e i r behavioral t a c t i c throughout t h e i r breeding l i f e s p a n . The exception r e s u l t e d when an o r i g i n a l l y tagged s a t e l l i t e male entered a small (approximately 1 m wide and 10-20 cm deep) offshoot of Thornvale Creek wi t h an e q u a l l y small female. Second s a t e l l i t e males had a lower rate of i n t e r a c t i o n (5.7 int/10 min) than alpha males (15.2 i n t / 1 0 min), and appeared to have a s i m i l a r r a t e of i n t e r a c t i o n compared to f i r s t s a t e l l i t e males (4.7 int/10 min)(Table 2.3)(Figure 2.1). S i m i l a r l y , r a d i o tagged f i r s t s a t e l l i t e males (n = 8) had a lower r a t e of 60 aggressive i n t e r a c t i o n s (mean 4.5 int/10 min) compared to tagged alpha males (9.3 i n t / 1 0 min) (Table 2.4) . U n l i k e f i r s t s a t e l l i t e males, second s a t e l l i t e males d i d not have the m a j o r i t y of t h e i r i n t e r a c t i o n s w i t h the male j u s t above them i n the h i e r a r c h y ( i . e . f i r s t s a t e l l i t e ) , but r a t h e r w i t h the alpha male (50%, Figure 2.2). Second s a t e l l i t e males occupied p o s i t i o n s e i t h e r d i r e c t l y behind or o f f to one side of the f i r s t s a t e l l i t e (forming a r i g h t angle t r i a n g l e w i t h the spawning p a i r ) . These circumstances seemed to t r i g g e r what i n t e r a c t i o n s were observed. When behind the f i r s t s a t e l l i t e , the second s a t e l l i t e would, without obvious provo c a t i o n , swim past the f i r s t s a t e l l i t e and i n t o the nest which immediately r e s u l t e d i n an attack from the alpha male. S i m i l a r l y , when forced to one side of the p a i r , the dominant male would d i r e c t more attacks at the second s a t e l l i t e though the reason f o r t h i s i s u n c l e a r . Jack males, were r a r e l y observed i n aggressive i n t e r a c t i o n s (2.4 i n t / 1 0 min) and o v e r a l l had fewer than other male t a c t i c s (Table 2.3) (Figure 2.1). The m a j o r i t y of jack i n t e r a c t i o n s (60%) occurred w i t h other i n t r u d i n g jack males f o r the nest p o s i t i o n (Figure 2.2). Jack contests were r e s o l v e d w i t h the same types of i n t e r a c t i o n s (attack and d i s p l a y phases) as was observed between competing alpha and s a t e l l i t e males. The h i g h e s t number of i n t e r a c t i o n s recorded between two j a c k males 61 i n any one contest was 43. In t h i s instance, the l o s e r occupied a p o s i t i o n behind a boulder adjacent to the spawning p a i r while the winner entered the nest. Effects of group formation and group size on rates of aggressive interaction Sixty-two breeding groups were i d e n t i f i e d , each comprised of a unique combination of males, having anywhere from one to f i v e male group members (Table 2.5). Competitive i n t e r a c t i o n data was s o r t e d by group type (1-5 males) and the e f f e c t of group s i z e on aggression l e v e l s analyzed. Aggression l e v e l s were found to d i f f e r s i g n i f i c a n t l y among mating groups of one to f i v e males ( K r u s k a l - W a l l i s 0.01 < P < 0.025) (Table 2.6). Intermediate s i z e groups had the lowest aggression l e v e l , 11.57 (2 males) and 13.49 (3 males) i n t e r a c t i o n s / 1 0 min. Small (one male) groups had much higher aggression l e v e l s (29.05 i n t e r a c t i o n s / 1 0 min) (Figure 2.3). The highest l e v e l of competitive i n t e r a c t i o n s occurred when only one male and one female were present (Figure 2.3). S i n g l e p a i r s were observed e a r l y i n the process of group formation. At t h i s time, l a r g e i n t r u d e r males o f t e n challenged the alpha f o r access to the newly a r r i v e d female. Thus, t h i s group type (group s i z e of one) represents i n t e r a c t i o n s between males adopting the same b e h a v i o r a l t a c t i c . In c o n t r a s t , groups c o n t a i n i n g 2 to 5 males represent 62 Table 2.5 Breeding groups observed i n Donovan and Thornvale Creeks during 1993/94 surveys. Group types i d e n t i f i e d contained one to f i v e males. In t o t a l , 62 breeding groups were observed. Group Type Number of Males Number of Groups A 1 10 A - S l 2 23 A - J 2 4 A - S l - J 3 6 A-S1-S2 3 9 A-S1-S2-J 4 8 A-S1-S2-S3 4 1 A-S1-S2-S3-J 5 1 Total Groups: 62 63 Table 2.6 Summary of male competitive i n t e r a c t i o n s i n r e l a t i o n to breeding groups. Rates of male competitive i n t e r a c t i o n s d i f f e r across breeding groups of 1 to 5 males (0.01 < P < 0.025) and across groups of 2 to 5 males (0.005 < P < 0.01) Group Size (No. of males) 1 2 3 4 5 No. of I n t e r a c t i o n s 753 756 481 523 87 No. of 10 minute Observation Periods 24 65 33 20 3 No. of Groups 10 27 15 9 1 Rate of Interaction Mean/10 min (SE) 29.05 (12.50) 11.57 (3.81) 13.49 (3.87) 27.30 (6.00) 29.00 64 45 40 -35 30 25 20 15 10 / / / / / / , *//< */ ••.••// .•' .••.•' / mm 2 3 4 Number of males .••Ssssss m Figure 2.3 Mean l e v e l s (+/-SE) of aggression i n r e l a t i o n to breeding group s i z e . Small and la r g e breeding groups had more frequent competitive i n t e r a c t i o n s than intermediate s i z e d groups. 65 i n t e r a c t i o n s between males adopting d i f f e r e n t reproductive t a c t i c s . To compare aggression l e v e l s among s i m i l a r group types, namely groups c o n t a i n i n g a combination of reproductive t a c t i c s , observations of s i n g l e p a i r s ( i . e . alpha only) were removed. Rates of male competitive i n t e r a c t i o n s f o r groups c o n t a i n i n g a l t e r n a t i v e reproductive t a c t i c s d i f f e r e d s i g n i f i c a n t l y across breeding groups of 2 to 5 males,(0.005 < P < 0.025)(Table 2.6). I n t e r a c t i o n s w i t h i n t r u d i n g males were removed to examine whether the observed d i f f e r e n c e i n aggression l e v e l s among groups was the r e s u l t of more i n t r u d e r s being present i n some group types than i n others. Comparisons across groups i n d i c a t e d that the ra t e s of male competitive i n t e r a c t i o n s among group members d i f f e r e d s i g n i f i c a n t l y across breeding groups of 2 to 5 males(Table 2.7)(P < 0.001). Since the frequency of i n t e r a c t i o n s appeared to increase w i t h group s i z e f o r male groups l a r g e r than one (Figure 2.3), re g a r d l e s s of the presence of i n t r u d e r s , i t was hypothesized that aggressive i n t e r a c t i o n s were more frequent i n l a r g e r groups simply because there are more males to i n t e r a c t . When rates of male competitive i n t e r a c t i o n s ( i n c l u d i n g i n t e r a c t i o n s w i t h intruders) were expressed as a f u n c t i o n of p a i r s of combatants, aggression l e v e l s d i d not d i f f e r s i g n i f i c a n t l y across breeding groups of 2 to 5 males (0.75 < P < 0.90)(Table 2.8). 66 T a b l e 2.7 Rates o f male c o m p e t i t i v e i n t e r a c t i o n s among group members o n l y ( i . e . i n t e r a c t i o n s w i t h i n t r u d e r males removed). Rates o f male c o m p e t i t i v e i n t e r a c t i o n s among group members d i f f e r a c r o s s b r e e d i n g groups o f 2 t o 5 males (P < 0.001) Group Size (No. of males) 2 3 4 5 No. o f I n t e r a c t i o n s 83 152 269 15 No. o f 10 minute O b s e r v a t i o n P e r i o d s 65 33 20 3 No. o f Groups 27 15 9 1 Rate of Interaction Mean/10 min (SE) 1.48 (0.41) 3.84 (0.88) 15.04 (4.26) 5.00 67 Table 2.8 Rates of male competitive i n t e r a c t i o n s expressed as a f u n c t i o n of the number of males i n a group ( p a i r s of combatants). Rates of male competitive i n t e r a c t i o n s as a f u n c t i o n of p a i r s of combatants do not d i f f e r across breeding groups of 2 to 5 males (0.75 < P < 0.90). Group Size (No. of males) 2 3 4 5 P a i r s o f Combatants 1 3 6 10 No. o f I n t e r a c t i o n s 756 481 523 87 No. o f 10 minute O b s e r v a t i o n P e r i o d s 65 33 20 3 No. o f Groups 27 15 9 1 Rate of Interaction Mean/10 min (SE) 11.57 (3.81) 4.50 (1.29) 4.67 (1.00) 2.90 68 Discussion The r e s u l t s of t h i s i n v e s t i g a t i o n showed that male competit i v e i n t e r a c t i o n s are i n f l u e n c e d by choice of reproductive t a c t i c and breeding group. Alpha males had much higher competitive investments than subordinate males (Table 2.3) . The m a j o r i t y of alpha male i n t e r a c t i o n s (85%) occurred with other large i n t r u d i n g males (Figure 2.2), when no s a t e l l i t e males were i n attendance ( i . e . e a r l y i n the process of group formation). The l o s e r of any contest f o r the dominant p o s i t i o n d i d not assume a subordinate p o s i t i o n w i t h i n the h i e r a r c h y , r a t h e r he moved on i n search of an a v a i l a b l e female. A l l s a t e l l i t e males i n t e r a c t e d p r i m a r i l y w i t h the dominant male. S a t e l l i t e males had very few i n t e r a c t i o n s w i t h l a r g e i n t r u d e r males but d i d defend t h e i r p o s i t i o n against s a t e l l i t e s i z e d i n t r u d e r males. Jacks had very few competitive i n t e r a c t i o n s w i t h group members, and i n t e r a c t e d p r i m a r i l y w i t h i n t r u d i n g j acks. Rates of aggressive i n t e r a c t i o n d i f f e r e d among breeding groups (1-5 males). Intermediate s i z e d groups (one alpha and one s a t e l l i t e ) had the lowest number of i n t e r a c t i o n s . The number of p o t e n t i a l combatants explained the i n c r e a s i n g l e v e l of aggression w i t h group s i z e . As expected, dominant males had the highest number of i n t e r a c t i o n s of any male type as they remained w i t h i n a 69 r e s t r i c t e d stream segment and were p r i m a r i l y concerned w i t h e x c l u d i n g other males from access to the female. I n t e r a c t i o n s were highest when there were no s a t e l l i t e males i n attendance. This group type of one male and one female represents the e a r l i e s t stage of group formation and the att e n d i n g male was f r e q u e n t l y challenged. Even when the alpha male was already engaged i n one contest, other challengers were w a i t i n g behind the combating p a i r ( s a t e l l i t e p o s i t i o n ) f o r t h e i r t u r n to compete f o r access to the newly a r r i v e d female. E s t a b l i s h i n g dominance e a r l y , i s important since i t appears that p r i o r r esidence determines the outcome of conte s t s . Of the 27 alpha dominance contests w i t h known outcomes only s i x r e s u l t e d i n alpha take-overs. Among lar g e pink salmon males, l e s s than 10% of alpha c h a l l e n g e r s are s u c c e s s f u l (Keenleyside and Dupuis 1988). The formation of a s i z e graded h i e r a r c h y i n coho was not the d i r e c t r e s u l t of the outcome of contests between hooknose males' w i t h the l o s e r s assuming the s a t e l l i t e p o s i t i o n . Alpha males c o n t i n u a l l y d i r e c t e d aggression to any s i m i l a r s i z e d male t h a t came i n t o the v i c i n i t y of the breeding group, even i f the i n t r u d e r d i d not d i r e c t l y challenge but attempted to take a s a t e l l i t e p o s i t i o n . Contests between l a r g e males r e s u l t e d i n the l o s e r moving on i n search of an a v a i l a b l e female r a t h e r than occupying a sub dominant p o s i t i o n w i t h i n the h i e r a r c h y (Chapter 70 1) . This s t r i c t adherence to a dominant t a c t i c and movement to another female rather than adopt a subordinate p o s i t i o n was a l s o r e p o r t e d f o r dominant male dark chub (Katano 1990) and pink salmon (Keenleyside and Dupuis 1988). Only once was a tagged dominant coho male observed adopting a s a t e l l i t e t a c t i c . L i k e alpha males, s a t e l l i t e males a l s o showed a s t r i c t adherence to t h e i r t a c t i c . U n l i k e dominant males,however, s a t e l l i t e males were o f t e n given the opportunity of assuming an a l t e r n a t i v e behavior. Dominant coho males, l i k e sockeye, l e f t the female f o r short periods, during which time the f i r s t s a t e l l i t e male assumed the dominant p o s i t i o n of c o u r t i n g and defending the female (Hanson and Smith 1967). However, upon the alpha males r e t u r n , the s a t e l l i t e male r e a d i l y r e l i n q u i s h e d h i s p o s i t i o n i n the nest. Given the asymmetry between dominant and s a t e l l i t e phenotypes (Chapter 1, Figure 1.5), e s c a l a t e d contests between the two male types were not expected to occur. S a t e l l i t e hooknose males d i d not gain access to mating through f i g h t i n g r e s u l t i n g i n f a r fewer i n t e r a c t i o n s than alpha males (Table 2.3) (Figure 2.1). Of the 48 groups observed c o n t a i n i n g f i r s t s a t e l l i t e males only 4 times was a f i r s t s a t e l l i t e ever challenged f o r h i s p o s i t i o n . The i n t e n s i t y of s a t e l l i t e contests was g r e a t l y reduced i n comparison w i t h that of alpha males and g e n e r a l l y , s a t e l l i t e s were observed j o i n i n g and lea v i n g mating p a i r s without a g o n i s t i c provocation. The low 71 l e v e l of aggressive i n t e r a c t i o n s recorded f o r s a t e l l i t e coho males i s c o n s i s t e n t w i t h the p r e d i c t i o n that males engaged i n extensive movement have l e s s to i n v e s t i n competition. As expected, f i r s t s a t e l l i t e males had the m a j o r i t y of t h e i r i n t e r a c t i o n s w i t h the male j u s t above them i n the h i e r a r c h y , the alpha male. However, cont r a r y to expectation, second s a t e l l i t e males had as many i n t e r a c t i o n s w i t h the alpha male as they d i d wit h f i r s t s a t e l l i t e . The second s a t e l l i t e would f r e q u e n t l y move towards the nest thereby s o l i c i t i n g a t t e n t i o n from the alpha male. I n t e r a c t i o n s between alpha and second s a t e l l i t e s may r e f l e c t reduced information on the females r e p r o d u c t i v e s t a t u s w i t h d i s t a n c e . Though a second s a t e l l i t e would gain v i s u a l i n f o r m a t i o n about the female by occupying the o u t l i e r p o s i t i o n ( i . e . o f f to one side of the f i r s t s a t e l l i t e ) , he may s t i l l be l a c k i n g o l f a c t o r y i n f o r m a t i o n regarding the female's reproductive s t a t e . I t has been demonstrated that v i s u a l i n f o r m a t i o n alone r e s u l t s i n lower m i l t (sperm) pr o d u c t i o n than when combined wi t h o l f a c t o r y cues (Olsen and L i l e y 1993). Second s a t e l l i t e s may move towards the nest and r i s k aggression from the dominant male i n order to gain i n f o r m a t i o n about the females reproductive s t a t e . Jack males competed among themselves f o r a p o s i t i o n i n the nest, d i r e c t l y under the p a i r , but had few i n t e r a c t i o n s w i t h other group members. The occurrence of t h i s "under your nose" 72 t a c t i c has al s o been reported f o r kokanee males mating w i t h sockeye p a i r s (Foote and L a r k i n 1988) and f o r dwarf A r c t i c charr (Svedang 1992) . Once i n the nest, coho jac k s were a c t i v e l y q u i v e r i n g the female. V i b r a t i o n a l communication or q u i v e r i n g , i s b e l i e v e d to provide valuable i n f o r m a t i o n on the female's reproductive s t a t e (Satou et a l . 1991). The aggressive behavior of a male depends not only on h i s t a c t i c but also on the mating group with which he i s as s o c i a t e d . In sockeye salmon, group aggressive a c t i v i t y was found to be hi g h e s t i n medium s i z e d groups (2-3 males) and lowest i n small (1 male) and large (4 or more males) groups (Quinn et a l . 1995) . In my study, however, the frequency of male coho i n t e r a c t i o n s was lowest i n medium s i z e d groups(one alpha and one s a t e l l i t e male), and highest i n small (alpha male) and l a r g e groups. This apparent d i f f e r e n c e i n group aggression patterns between the two salmon species may r e s u l t , i n p a r t , from the f a c t that i n the sockeye study, i n t r u d e r s were i n c l u d e d as group members. Since competitive i n t e r a c t i o n s e s c a l a t e when s i m i l a r s t r a t e g i s t s are present (Whitehouse 1991), l e v e l s of male aggressive a c t i v i t y were expected to increase w i t h i n c r e a s i n g numbers of s a t e l l i t e s . W i thin group i n t e r a c t i o n ( i . e . i n t e r a c t i o n s w i t h i n t r u d e r s not included) r a t e s increased with number of males. The r e s u l t s of t h i s i n v e s t i g a t i o n i n d i c a t e that group aggression l e v e l s are explained by the number of 73 males ( p o t e n t i a l p a i r s of combatants) as was p r e d i c t e d . Alpha males had the m a j o r i t y of t h e i r aggressive i n t e r a c t i o n s with non-group males. High l e v e l s of aggressive i n t e r a c t i o n s w i t h non-group males have a l s o been reported f o r dominant pink salmon males (Keenleyside and Dupuis 1988). Dominant pink males d i r e c t e d 79% of i n t e r a c t i o n s at non-group members during non-spawning periods ( i . e . not w i t h i n 15 minutes of spawning, Keenleyside and Dupuis 1988). However w i t h i n 15 minutes of spawning, 53% of t h e i r aggressive i n t e r a c t i o n s were d i r e c t e d at group members (Keenleyside and Dupuis 1988). The aggression towards group members i n pink salmon r e s u l t e d from s a t e l l i t e s rushing the nest as the female crouches j u s t p r i o r to spawning, a behavior a l s o e x h i b i t e d by s a t e l l i t e coho males. In a d d i t i o n , Keenleyside and Dupuis (1988) reported that more s a t e l l i t e pink salmon males j o i n e d a breeding group s h o r t l y b efore the female spawned. In t h i s i n v e s t i g a t i o n , f i v e a c t u a l spawning events were observed and four of the f i v e spawning groups contained three or more males. Given th a t the most commonly observed group type was one alpha and one s a t e l l i t e male (23 out of 62 groups) , these observations suggest that coho s a t e l l i t e s may al s o j o i n mating groups s h o r t l y before spawning approaches. Many of the b e h a v i o r a l observations gathered during t h i s i n v e s t i g a t i o n have not been reported before f o r coho salmon and 74 may be used to speculate about costs of reproduction f o r male types. While s a t e l l i t e males appear to i n v e s t t h e i r energy reserves i n t o movement among breeding groups and l i t t l e i n t o competition, alpha males i n v e s t more resources i n competitive i n t e r a c t i o n s than other t a c t i c s . The high competitive costs f o r dominant males, a s t r i c t adherence to b e h a v i o r a l t a c t i c s , combined w i t h an abundance of small hooknose males i n the p o p u l a t i o n i s evidence against strong s e l e c t i o n f o r l a r g e male s i z e . 75 CHAPTER III INFLUENCE OF ENVIRONMENT ON Behavior Introduction Spawning coho are subject to dramatic f l u c t u a t i o n s i n environmental c o n d i t i o n s as they spawn during the f a l l and winter months, when p r e c i p i t a t i o n i s highest, and temperatures lowest. Environmental c o n d i t i o n s i n f l u e n c e male coho reproductive t a c t i c success through a v a r i e t y of mechanisms i n c l u d i n g a l t e r a t i o n of h a b i t a t (high flows may remove small woody d e b r i s r e s u l t i n g i n reduced sneaking o p p o r t u n i t i e s f o r j a c k s ; Gross 1991), energetic costs (increased flows r e s u l t i n energy reserves being depleted f a s t e r i n small s a t e l l i t e males than i n large alpha males; Fukushima 1994), and access to mates (decreased flows i n h i b i t manoueverability of l a r g e r alpha males compared to smaller s a t e l l i t e and jack males). U l t i m a t e l y , p h y s i c a l c o n d i t i o n s are b e l i e v e d to r e s u l t i n changes i n the frequency of male l i f e - h i s t o r y s t r a t e g i e s i n coho populations (Gross 1991). The jack l i f e h i s t o r y strategy i n coho males, r e l i e s on the a v a i l a b i l i t y of s u i t a b l e refuges from which to 'sneak' f e r t i l i z a t i o n s (Gross 1985). S u i t a b l e refuges r e f e r to depressions, debris, boulders and undercut banks. In one study, when debris was introduced to a stream segment, the frequency of jacks i n the area increased (Gross 1991). 76 Environmental c o n d i t i o n s a l s o ' determine ad u l t salmon movement p a t t e r n s . Entrance of a d u l t s to spawning t r i b u t a r i e s corresponds w i t h an increase i n flow (Neave 1943, Briggs 1953, Shapovalov and Taft 1954, Banks 1969, Sandercock, 1991) . I f environmental conditions are not s u i t a b l e ( i . e . low flow and low temperature), the run may be i n t e r r u p t e d (Briggs 1953) . Coho may wait weeks, even months fo r conditions to change (Sandercock 1991). Temperature i s b e l i e v e d to i n f l u e n c e a c t i v i t y though to a l e s s e r degree than flow (Banks 1969, Sandercock 1991). Since p h y s i c a l c o n d i t i o n s may i n f l u e n c e spawning success, the o b j e c t i v e of t h i s chapter was to present i n f o r m a t i o n on the p h y s i c a l character of spawning areas i n Kanaka Creek and i t s t r i b u t a r i e s i n a d d i t i o n w i t h data on weather and stream flows f o r 1992 and 1993 and to d i s c u s s i t i n r e l a t i o n to the movements, aggression and spawning behavior of male reproductive t a c t i c s . Entrance i n t o spawning t r i b u t a r i e s was p r e d i c t e d to be r e l a t e d to i n c r e a s i n g flows. In extreme high flows, movement was expected to be l i m i t e d as e n e r g e t i c costs of m i g r a t i o n i n c r e a s e d . Under c o n d i t i o n s of minimal flow, l a r g e males were predicted to have d i f f i c u l t y , manoeuvring i n shallow t r i b u t a r i e s . Low flows were thought to increase the cost of defending a female as dominant males ( t y p i c a l l y the l a r g e s t males) must pursue r i v a l males without the f u l l buoyancy of water and r i s k 77 of predation may increase. Under conditions of low temperatures and flows, a l l male coho reproductive t a c t i c s were p r e d i c t e d to have reduced l i f e s p a n , movement, and competitive i n t e r a c t i o n s . Methods Data on the p h y s i c a l character of Kanaka Creek and i t s t r i b u t a r i e s was c o l l e c t e d during a h a b i t a t survey conducted i n November 1993. Two 100 m s e c t i o n s , (upper and lower), i n each of the two t r i b u t a r i e s (Donovan and Thornvale). and .three- 100 m s e c t i o n s , (lower, middle and upper) i n Kanaka mainstem were sampled to c l a s s i f y h a b i t a t . V a r i a b l e s measured in c l u d e d r i p a r i a n h a b i t a t , depth, v e l o c i t y , oxygen, t u r b i d i t y , and substrate composition. The r e s u l t s of the h a b i t a t survey are presented i n Appendix. However, only width, depth, and temperature measurements are discussed s p e c i f i c a l l y as they r e l a t e to c o n c l u s i o n s . Sampling of Kanaka mainstem was conducted on 1 and 2 Nov., 1993. Both Donovan and Thornvale t r i b u t a r i e s were sampled on 3 Nov., 1993. Water temperature and p r e c i p i t a t i o n records from 1992-94 fo r Kanaka Creek were obtained from John Heaven, manager of the B e l l - I r v i n g Hatchery. S i m i l a r measurements were not a v a i l a b l e f o r the two spawning t r i b u t a r i e s , Donovan and Thornvale. Results Kanaka mainstem and two of i t s t r i b u t a r i e s , Donovan and Thornvale Creeks, are a l l used by spawning coho yet d i f f e r i n 78 t h e i r p h y s i c a l c h a r a c t e r i s t i c s (Table 3.1). Thornvale Creek i s shallow, narrow (Table 3.1), and has l i m i t e d access during most of the year. P r e c i p i t a t i o n i s r e q u i r e d during spawning or Thornvale t r i b u t a r y r a p i d l y diminishes to a t r i c k l e of flow and becomes unnavigable. The t i m i n g of the coho run, during the w i n t e r months (Nov-Jan i s t y p i c a l l y a p e r i o d of high p r e c i p i t a t i o n ) , i s c r i t i c a l as i t ensures coho the high water flows required to reach and spawn s u c c e s s f u l l y i n n a t a l streams. As p r e d i c t e d , entrance i n t o spawning t r i b u t a r i e s was r e l a t e d to i n c r e a s i n g flows. Two radio tagged males, one alpha and one jack, entered Thornvale and Donovan t r i b u t a r i e s fourteen days a f t e r capture on 21 Nov 1992 (Figure 3.1). Their movement int o t r i b u t a r i e s corresponded with an increase i n p r e c i p i t a t i o n and an increase i n temperature (Figure 3.1). However, increased p r e c i p i t a t i o n was a l s o a s s o c i a t e d with decreased spawning a c t i v i t y i n Thornvale Creek. During the n i g h t s of 12 Dec 1993 (Figure 3.1), heavy r a i n f a l l r e s u l t e d i n t u r b i d water c o n d i t i o n s and i n h i b i t e d spawning behavior as f i s h held along the banks. One radio tagged male e v e n t u a l l y l e f t the t r i b u t a r y and entered Kanaka mainstem. In 1993, there was an i n t e r r u p t i o n i n the Kanaka Creek coho run that corresponded w i t h a p e r i o d of extreme low temperatures and flows (20 - 26 Dec Figure 3.1). Under these c o n d i t i o n s , male coho were observed to have d i f f i c u l t y n a v i g a t i n g Thornvale 79 Table 3.1 P h y s i c a l c h a r a c t e r i s t i c s of coho spawning h a b i t a t i n Kanaka Creek and two of i t s t r i b u t a r i e s , Donovan and Thornvale Creeks. Habitat measurements c o i n c i d e w i t h the beginning of the coho run i n 1993. Physical Ch a r a c t e r i s t i c s Kanaka Donovan Thornvale lower upper lower upper lower upper Date 1993 2-Nov 2-Nov 3-Nov 3-Nov 3-Nov 3-Nov Mean w i d t h (m) (SE) 13.07 (0.4) 7.81 (0.37) 2 . 39 (0.11) 3.25 (0.1) 2 . 34 (0.16) 2 .11 (0.14) Mean d e p t h (cm) (SE) 27.66 (2.55) 39.38 (4.94) 17 .76 (1-29) 17 . 15 (2.03) 8.79 (1-72) 7 . 69 (0.67) Temp (°C) 8.5 8 10 10 9.3 9.5 V e l o c i t y (cm/s) 58 . 3 16.3 66. 6 91.1 34 . 5 16.1 80 1992 -aver temp -precip Date F i g u r e 3.1 Mean d a i l y temperature and p r e c i p i t a t i o n f o r Kanaka Creek d u r i n g the coho spawning p e r i o d f o r b o t h y e a r s o f s t u d y (1992 and 1993). 81 t r i b u t a r y , t h r a s h i n g and f l a i l i n g themselves over exposed substrate to move between shallow depressions c o n t a i n i n g water. A c t i v i t y l e v e l s f o r a l l male types were reduced, p a r t i c u l a r l y the migrations of s a t e l l i t e males (Figure 3.2). The mean d a i l y distance moved by tagged s a t e l l i t e males during the i n t e r r u p t e d run p e r i o d (20-26 Dec), was l e s s than h a l f that of the peak of the run from 2 8 Nov to 10 Dec (Figure 3.2). As flows and temperatures increased to pre 2 0 Dec. c o n d i t i o n s , a group of f r e s h l y a r r i v e d males entered the spawning t r i b u t a r i e s . However, these l a t e a r r i v i n g males had migrations s i m i l a r (Figure 3.2) to males captured during the run i n t e r r u p t i o n (20 Dec. 1993). In sockeye salmon, the reduced movement l a t e i n the season i s s a i d to r e f l e c t a l a c k of a v a i l a b l e females as the operating sex r a t i o (OSR) becomes male b i a s e d (Quinn et a l . 1995). Unfortunately, data were not a v a i l a b l e to determine the Kanaka Creek coho OSR's throughout the spawning season, though I noted few females or ja c k s on the spawning grounds during January 1994. During the run i n t e r r u p t i o n , the low flows and temperatures may have also increased the r i s k of p r e d a t i o n . This p e r i o d was the only occasion when otherwise vigorous f i s h were observed h o l d i n g on redds without eyes as a r e s u l t of blue heron predation. I observed an increase i n the number of raccoon and bear t r a c k s along the Creek combined w i t h an abundance of 82 F i g u r e 3.2 Mean d a i l y d i stance (m) migrated by male coho of d i f f e r e n t reproductive t a c t i c s i n r e l a t i o n to run p e r i o d . The run i n t e r r u p t i o n r e f l e c t s a p e r i o d of low flows and temperatures (20 Dec to 26 Dec, 1993). 83 f r e s h l y t o r n carcasses along the shore. In one insta n c e , males belonging to a tagged breeding groups were observed h o l d i n g formation even though the groups' female had been k i l l e d and was on the adjacent bank. Unexpectedly, the competitive i n t e r a c t i o n s among males continued even i n the absence of females. S i x tagged males, four dominant hooknose males and two s a t e l l i t e s , were observed competing without a female from 20 Dec. to 10 Jan. (Table 3.2). Contests often e s c a l a t e d r e s u l t i n g i n a high r a t e of aggressive i n t e r a c t i o n s (Table 3.2). P r i o r to the run i n t e r r u p t i o n (20 Dec. to 10 Jan.), males were only observed competing i n the presence of a female. The inherent aggression towards other males (regardless of female presence), and the l i m i t e d movement observed by dominant males w i t h i n a r e s t r i c t e d stream segment (Chapter 1) suggests t e r r i t o r i a l i t y among alpha males. Discussion Entry of coho males i n t o spawning t r i b u t a r i e s corresponded w i t h i n c r e a s e d p r e c i p i t a t i o n . As much as two t h i r d s of the Kanaka Creek coho run spawns i n t r i b u t a r i e s (Murdoch 1988). The r e l a t i o n s h i p between ascent of spawning streams and flow has been documented i n A t l a n t i c salmon (Jensen et a l . 1986, Webb 1989, Hawkins 1989, Webb and Hawkins 1989) and i n P a c i f i c salmonids (Neave 1943, Briggs 1953, Shapovolov and Taft 1954, Fukushima 1994). When temperatures and flow decreased 84 Table 3.2 Male-male competitive i n t e r a c t i o n s i n the absence of females. This behavior was not observed during the peak of the run. Levels of competitive investment are s i m i l a r to those when a female i s present and a c t i v e l y d i g g i n g . Date Location (m) Floy tag Tactic Group Size Interactions/10 min 22 Dec 180 G r e y l Alpha 2 88 22 Dec 180 G r e y l Alpha 2 30 22 Dec 180 G r e y l Alpha , 2 94 3 Jan 95 Grey2 Alpha 2 84 4 Jan 355 Orange Alpha 2 8 5 Jan 85 Yellow Alpha 3 8 5 Jan 85 Yellow Alpha 3 16 5 Jan 250 Green S a t e l l i t e 3 14 5 Jan 235 Black S a t e l l i t e 2 12 85 d r a m a t i c a l l y during the week of 20-26 Dec. 1993 , manoeuvrability was i n h i b i t e d , and movement decreased. E n t e r i n g t r i b u t a r i e s when flows are high ensures s u c c e s s f u l n a v i g a t i o n of the spawning grounds. As expected, poor (low temperatures and flows) p h y s i c a l conditions r e s u l t e d i n reduced a c t i v i t y f o r a l l male b e h a v i o r a l types. During storm events i n Thornvale Creek, t u r b i d i t y increased, spawning behavior ceased, and f i s h h e l d c l o s e to the bank. Fukushima (1994) a l s o reported .a time l a g between peak discharge and resumption of spawning a c t i v i t y of Hucho perryi (Salmonidae) i n Japan, w i t h l e s s of a delay i n sma l l e r Creeks than i n l a r g e r Creeks. This most l i k e l y r e s u l t e d from a more r a p i d flow s t a b i l i z a t i o n i n a t r i b u t a r y i n comparison w i t h a l a r g e r system. M a i n t a i n i n g p o s i t i o n during high flow w i l l i n c r e a s e the ene r g e t i c cost of reproduction, and gametes r e l e a s e d during high flows may be l o s t (washed downstream). Though flows and temperatures increased i n January (to l e v e l s comparable to the beginning and peak of the run) , movement of both alpha and s a t e l l i t e males was reduced i n comparison w i t h e a r l i e r i n the season. Seasonal movement pattern d i f f e r e n c e s have also been described f o r A t l a n t i c salmon where the r a t e and distance of movement decreased as the spawning season progressed (Power and McCleave, 1991) . The l a c k of movement towards the end of the spawning season may r e f l e c t 86 a l a c k of unspawned females (Quinn et a l . 1995). Unexpectedly, the competitive i n t e r a c t i o n s among males continued i n the absence of females. Defending a stream segment, rather than searching f o r an a v a i l a b l e female suggests t e r r i t o r i a l i t y among alpha males and may prove adaptive i f the p r o b a b i l i t y of dominating other females i n the v i c i n i t y i s higher than elsewhere. Spawning behavior i s i n f l u e n c e d by the p h y s i c a l c o n d i t i o n s on the spawning grounds. Increases i n temperature and p r e c i p i t a t i o n correspond w i t h entrance to spawning t r i b u t a r i e s ; however, extreme p r e c i p i t a t i o n appears to have a negative impact on spawning behavior. Low flows and low temperatures r e s u l t e d i n reduced movement and competitive i n t e r a c t i o n s f o r a l l male b e h a v i o r a l types. Therefore, fu t u r e i n v e s t i g a t i o n s examining coho repr o d u c t i v e s t r a t e g i e s should consider the i n f l u e n c e of environmental c o n d i t i o n s on behavior and u l t i m a t e l y the reproductive success of males adopting d i f f e r e n t t a c t i c s . 87 SUMMARY AND CONCLUSIONS The hooknose t a c t i c has p r e v i o u s l y been considered as a pure s t r a t e g y i n which males compete f o r access to females and competitively i n f e r i o r males form a s i z e graded h i e r a r c h y behind the spawning p a i r (Gross 1985). Intermediate s i z e d hooknose are beli e v e d to be s e l e c t e d against as they can perform n e i t h e r the sneaking t a c t i c of jacks or the f i g h t i n g t a c t i c of l a r g e r males, e f f e c t i v e l y (Gross 1985). The r e s u l t s of t h i s study; however, do not support t h i s hypothesis. S a t e l l i t e p o s i t i o n s i n breeding groups of Kanaka Creek coho were e x c l u s i v e l y occupied by intermediate s i z e d hooknose males which lacked the s i z e , enlarged kypes, d o r s a l humps and b r i g h t c o l o r a t i o n , c h a r a c t e r i s t i c of l a r g e r , dominant hooknose males (Chapter 1) . While s a t e l l i t e hooknose males moved both frequently and e x t e n s i v e l y and o f t e n entered m u l t i p l e waterways during t h e i r breeding l i f e s p a n , dominant hooknose males remained w i t h i n a r e s t r i c t e d stream segment, accessing the females w i t h i n (Chapter 1). Contests between hooknose males f o r the alpha p o s i t i o n d i d not r e s u l t i n the l o s e r occupying a subordinate p o s i t i o n w i t h i n the h i e r a r c h y . The unsuccessful male, a f t e r i n v e s t i n g c o n s i d e r a b l e resources i n competitive i n t e r a c t i o n s during the con t e s t , l e f t i n search of another female. E s c a l a t e d contests between alpha and s a t e l l i t e hooknose males d i d not occur. Large 88 males b a t t l e d each other f o r dominance while intermediates b a t t l e d one another f o r s a t e l l i t e p o s i t i o n s . Of the 29 hooknose males tagged, only once d i d a male change s t a t u s . Even when o l d and near death, l a r g e males were not found to occupy f i r s t s a t e l l i t e p o s i t i o n . The r e s i d e n t alpha was aggressive to any s i m i l a r s i z e d male, re g a r d l e s s of c o n d i t i o n , that attempted to s i t behind the nest, e v e n t u a l l y f o r c i n g him to leave the area. Mating groups observed were comprised of 1 - 5 males (Chapter 2) . Within those groups, spawning p a i r s w i t h one s a t e l l i t e male i n attendance had the lowest rates of aggression. The h i g h e s t l e v e l of competitive i n t e r a c t i o n s occurred when no s a t e l l i t e s were i n attendance ( i . e . one female and one male). P a i r s without s a t e l l i t e s occur during the e a r l y stages of group formation. When a newly a r r i v e d female appears, she represents maximum reproductive payoff f o r any one f e r t i l i z a t i o n event as a higher p r o p o r t i o n of the females t o t a l eggs are deposited i n the f i r s t nest she constructs (Schroder 1981). I f the group has been es t a b l i s h e d f o r some time, i n t r u d e r males may choose to move on i n search of another female r a t h e r than i n v e s t s i g n i f i c a n t resources competing f o r a female who may already be p a r t i a l l y spawned. The b e n e f i t s of moving on i n search of another female may be f u r t h e r a m p l i f i e d by the f a c t that p r i o r residence often determines the outcome of contests between l a r g e males (Chapter 2) . 89 I f l i f e t i m e reproductive success i s devalued by competitive i n t e r a c t i o n s r e q u i r e d to maintain p o s i t i o n i n a mating group ( i e . energy expended decreases breeding l i f e s p a n and th e r e f o r e breeding o p p o r t u n i t i e s ) , then choosing to i n v e s t i n aggressive i n t e r a c t i o n s when the payoff i s low may r e s u l t i n reduced f i t n e s s . The costs of reproduction accepted by each t a c t i c should r e f l e c t the payoff of the behavior. That i s , s e l e c t i o n should favour " l o v e r s " where f e r t i l i z a t i o n success i s low and " f i g h t e r s " where i t i s high. I propose that the hooknose l i f e h i s t o r y s t r a t e g y i s comprised of two t a c t i c s : alpha and s a t e l l i t e where l a r g e alpha type males adopt a f i g h t i n g r e s i d e n t t a c t i c , and intermediate s a t e l l i t e males a l e s s competitive moving t a c t i c , where both t a c t i c s are s u c c e s s f u l . The d e f i n i t i o n of a mixed s t r a t e g y requires, (1) the payoffs f o r each behavior be equal and (2) the pay o f f s be negative frequency dependant, ( i . e . f i t n e s s i n c r e a s i n g as frequency of t a c t i c decreases, Maynard Smith 1982). I could f i n d only two studies which used same aged males to determine dominant and s a t e l l i t e gametic c o n t r i b u t i o n s . Schroder (1981), examined seven chum s a t e l l i t e males and Chebanov, (1983) three sockeye s a t e l l i t e males. The s i z e of s a t e l l i t e s r e l a t i v e to the dominant male was a v a i l a b l e f o r the sockeye study only and showed l i t t l e asymmetry (2-3 cm d i f f e r e n c e i n length) between dominant and f i r s t s a t e l l i t e , 90 Chebanov (1983). Both i n v e s t i g a t o r s concluded that s a t e l l i t e gametic c o n t r i b u t i o n was l e s s than dominant males. However, the r e s u l t s of t h i s i n v e s t i g a t i o n would suggest t h a t a l l males used i n Chebanov's arena were i n f a c t alpha males f o r c e d to adopt p o s i t i o n s and b e h a v i o r a l t a c t i c s they would not normally assume i n a n a t u r a l environment. Therefore, the f e r t i l i z a t i o n success achieved by the reproductive t a c t i c s alpha and s a t e l l i t e during a s i n g l e spawning event r e q u i r e s f u r t h e r study and the r e s u l t s of t h i s i n v e s t i g a t i o n should caution researchers against using s i m i l a r s i z e d coho males i n an arena. Assuming, f o r the moment, that s a t e l l i t e males do have reduced gametic c o n t r i b u t i o n compared w i t h dominant males, the behavior of moving may increase the rep r o d u c t i v e success of s a t e l l i t e hooknose males by e i t h e r of two mechanisms; 1) by producing a greater number of encounters w i t h females which may r e s u l t i n s i m i l a r cumulative f e r t i l i z a t i o n s compared with dominant hooknose males or 2) by expanding the geographic d i s t r i b u t i o n of f e r t i l i z a t i o n s which would ensure some re p r o d u c t i v e success i n the event of nest d e s t r u c t i o n (females o f t e n d i g up other females nests, f l o o d s , droughts or other c a t a s t r o p h i c environmental events, van den Burghe 1984). Dominant males which r e s i d e i n a small segment of stream and access few females would s u f f e r g r e a t l y i n the event of nest d e s t r u c t i o n as ' a l l t h e i r eggs are i n one basket'. There i s reason to expect that as the number of s a t e l l i t e 91 males increases, there i s a decrease i n i n d i v i d u a l f i t n e s s . In t h i s i n v e s t i g a t i o n , observations of gamete r e l e a s e i n d i c a t e d t h a t d i s t a n t s a t e l l i t e males ( i . e . t h i r d s a t e l l i t e s ) d i d not p a r t i c i p a t e i n gamete r e l e a s e . During the f i v e a c t u a l spawning events witnessed i n t h i s i n v e s t i g a t i o n , the alpha male was on one side of the female and the f i r s t s a t e l l i t e on the other (the j a c k was underneath the female). Any second s a t e l l i t e present was f o r c e d to the outside of the f i r s t s a t e l l i t e male which r e s u l t e d i n him being p o s i t i o n e d outside of the nest. However, the gametic c o n t r i b u t i o n of t a c t i c s r e l a t i v e to t h e i r p o s i t i o n i n the group remains to be determined. Many of the b e h a v i o r a l observations gathered during t h i s i n v e s t i g a t i o n have not been reported before f o r coho salmon as the p r e v a i l i n g view of coho salmon reproduction i s based on pieces of data from d i f f e r e n t species. Male coho competitive i n t e r a c t i o n s are i n f l u e n c e d by choice of r e p r o d u c t i v e t a c t i c , b reeding group, and by non-group males encountered on the breeding grounds. In summary, the evidence gathered during t h i s i n v e s t i g a t i o n shows that the e v o l u t i o n and maintenance of the hooknose mating s t r a t e g y i n coho populations i s more complex than p r e v i o u s l y described. While s a t e l l i t e males appear to i n v e s t t h e i r energy reserves i n t o movement among breeding groups and l i t t l e i n to competition, alpha males i n v e s t more resources i n competitive i n t e r a c t i o n s than other t a c t i c s . These d i f f e r e n c e s i n hooknose 92 male reproductive behaviors combined w i t h a s t r i c t adherence to behavioral t a c t i c s , and an abundance of small hooknose males i n the p o p u l a t i o n suggests that the s a t e l l i t e t a c t i c i s not an unsuccessful one. Thus, the r e s u l t s of t h i s study support the idea that the hooknose l i f e h i s t o r y s t r a t e g y i s comprised of two a l t e r n a t i v e reproductive t a c t i c s r a t h e r than the s i n g l e , f i g h t i n g t a c t i c that has p r e v i o u s l y been a s c r i b e d to the hooknose s t r a t e g y . 93 B i b l i ography A l l e n , G. H. 1956. M i g r a t i o n , d i s t r i b u t i o n , and movement of Puget Sound s i l v e r salmon. Doctoral d i s s e r t a t i o n , U n i v e r s i t y of Washington, S e a t t l e . Banks, J. W. 1969. A review of the l i t e r a t u r e on the upstream m i g r a t i o n of adult salmonids. J . F i s h B i o l . 1: 85-136. B a g l i n i e r e , J . , G. Maisse, and A. Nihouarn. 1991. R a d i o - t r a c k i n g of male adu l t A t l a n t i c salmon, Salmo salar L., during the l a s t phase of spawning m i g r a t i o n i n a spawning stream (Brittany, France). Aquatic L i v i n g Resources, 4: 161-167. B a g l i n i e r e , J . , G. Maisse, and A. Nihouarn. 1990. Migr a t o r y and reproductive behavior of female adult A t l a n t i c salmon, Salmo salar L., i n a spawning stream. J . F i s h . B i o l . 36: 511-520. B r e t t , J.R. and D. MacKinnon. 1954. Some aspects of o l f a c t o r y p e r c e p t i o n i n mi g r a t i n g adult coho and s p r i n g salmon. J . F i s h . Res. Board Can. 11: 310-318. Briggs, J. C. 1953. The behavior and reproduction of salmonid f i s h e s i n a small c o a s t a l stream. C a l i f . Dept. F i s h and Game, F i s h B u l l . 94. 62 pp. Chebanov, N.A. 1980. Spawning behavior of the pink salmon, Oncorhynchus gorbuscha. J. I c h t h y o l . 20(6): 64-73. Chebanov, N. A., N. V. Varnavskaya and V. S. Varnavskiy. 1983. E f f e c t i v e n e s s of spawning of male sockeye salmon, Oncorhynchus nerka (Salmonidae) , of d i f f e r i n g h i e r a r c h i a l rank by means of genetic biochemical markers. J . I c h t h y o l . 23: 51-55 E i l e r , J. H. 1988. Use of radio telemetry f o r studying f i s h i n lar g e t u r b i d r i v e r s . B iotelemetry X: 205-209. E l l i s , D.V. 1962. Preliminary studies on the v i s i b l e migrations of a d u l t salmon. C.J.F.A.S., 19(1): 137-148. Fleming, I.A. and M.R. Gross. 1989. E v o l u t i o n of adul t female l i f e h i s t o r y and morphology i n a p a c i f i c salmon (coho: Oncorhynchus kisutch). E v o l u t i o n 43(1): 141-157. Fleming, I. A., and M.R. Gross. 1993. Breeding success of hatchery and w i l d coho salmon {Oncorhynchus kisutch) i n 94 competition. E c o l o g i c a l A p p l i c a t i o n s . 3(2): 230-245. Fleming, I.A. and M.R. Gross. 1994. Breeding competition i n a p a c i f i c salmon (coho: Oncorhynchus kisutch) : measures of n a t u r a l and sexual s e l e c t i o n . E v o l u t i o n , 48(3): 637-657. Foote, C. J. 1988 . Male mate choice i n f i s h e s : a review of the evidence i n Coho salmon. Anim. Behav., 36: 1228-1253. Foote, C.J. 1989. Female mate preference i n p a c i f i c salmon. Animal Behavior 38, 721-723. Foote, C.J. and P.A. L a r k i n . 1988. The r o l e of male choice i n the a s s o r t a t i v e mating of anadromous and non-anadromous sockeye salmon. Behavior. 106, 43-62. Fraley, J. J . , and B. B. Shepard. 1989. L i f e h i s t o r y , ecology and p o p u l a t i o n s t a t u s of migratory b u l l t r o u t {Salvelinus confluentus) i n the Flathead lake and r i v e r system, Montana. Northwest Science. 63 (4) : 133-143. Fraser, F.J., E.A. Perry,and D.T. L i g h t l y . 1983. B i g Qualicum R i v e r salmon development p r o j e c t . Volume 1: a b i o l o g i c a l assessment 1959-1972. Can. Tech. Rep. Fish.. Aquat. S c i . 1189: 198 p. F r e t w e l l , M. 1981. M i g r a t i o n of adult sockeye salmon i n the Nechako r i v e r system i n 1980, I n t e r n a t i o n a l p a c i f i c salmon f i s h e r i e s commission, pp 49. Fukushima, M. 1994. Spawning m i g r a t i o n and redd c o n s t r u c t i o n of S a k h a l i n taimen, Hucho perryi (Salmonidae) on northern Hokkaido I s l a n d , Japan. J. F i s h . B i o l . 43: 877-887. Gardner, R., M. R. Morris, and C. E. Nelson. 1987. C o n d i t i o n a l e v o l u t i o n a r i l y s t a b l e s t r a t e g i e s . Anim. Behav., 35: 507-517. Grey, R. H. and J. M. Haynes. 1979. Spawning m i g r a t i o n of ad u l t Chinook salmon {Oncorhynchus tshawytscha) c a r r y i n g e x t e r n a l and i n t e r n a l r a d i o t r a n s m i t t e r s . J . F i s h Res. Board Can. 36: 1060-1064. Groot, C. C , and M a r g o l i s , L. 1991. P a c i f i c salmon l i f e h i s t o r i e s . Vancouver, U n i v e r s i t y of B.C. Press. Gross, M. R. 1984. Sunfish, salmon and the e v o l u t i o n of a l t e r n a t i v e reproductive s t r a t e g i e s and t a c t i c s i n f i s h e s . 95 In: F i s h Reproduction: S t r a t e g i e s and T a c t i c s (ed. by R. Wootton and G. P o t t s ) , pp 55-75, London, Academic Press. Gross, M. R. 1985. D i s r u p t i v e s e l e c t i o n f o r a l t e r n a t i v e l i f e h i s t o r i e s i n salmon. Nature. 313: 47-48. Gross, M.R. 1991. Salmon breeding behavior and l i f e h i s t o r y e v o l u t i o n i n changing environments. Ecology, 72 (4): 1180-1186. Hanson, A.J., and H.D. Smith. 1967. Mate s e l e c t i o n i n a population of sockeye salmon {Oncorhynchus nerka) of mixed age-groups. J. F i s h . Res. Bd. Can. 24 (9): 1955-1977. Hawkins, A. D. and G. W. Smith. 1986. R a d i o - t r a c k i n g observations on A t l a n t i c salmon ascending the Aberdeenshire Dee. Sc o t t . F i s h . Res. Rep. No. 36. Heard, W.R. 1972. Spawning behavior of pink salmon on an a r t i f i c i a l redd. Trans. Amer. F i s h . S o c , 2: 276-283. Hartt, A.C. and M.B. D e l l . 1986. E a r l y oceanic migrations and growth of j u v e n i l e P a c i f i c salmon and steelhead t r o u t . I n t . North Pac. F i s h . Comm. B u l l . 46: 105 p. Heggberget, T. G., L. P. Hansen and T. F. Naesje. 1988. W i t h i n - r i v e r spawning m i g r a t i o n of A t l a n t i c salmon {Salmo salar). Can. J. F i s h . Aquat. S c i . 45: 1691-1698. Holtby, B.L. & M.C. Healey. 1990. S e x - s p e c i f i c l i f e h i s t o r y t a c t i c s and r i s k - t a k i n g i n coho salmon. Ecology, 71(2). p.678-690. Hoopes, D. T. 1972. S e l e c t i o n of spawning s i t e s by sockeye salmon i n small streams. F i s h . B u l l . 70(2): 447-458. Hutchings, J. A. and R. A. Myers. 1988. Mating success of a l t e r n a t i v e maturation phenotypes i n male A t l a n t i c salmon, Salmo s a l a r . Oecologia. 75: 169-174. Hutchings, J. A. and R. A. Myers. 1994. The e v o l u t i o n of a l t e r n a t i v e mating s t r a t e g i e s i n v a r i a b l e environments. E v o l . E c o l . 8: 256-268. Jensen, A.J., T.G. Heggberget and B.O. Johnsen. 1986. Upstream migration of adult A t l a n t i c salmon, Salmo salar L., i n the R i v e r Vefsna, northern Norway. J. F i s h . B i o l . 29: 459-465. 96 Jonsson, N., B. Jonsson and L.P. Hansen. 1991. Ene r g e t i c cost of spawning i n male and female A t l a n t i c salmon {Salmo salar L.) Journal of F i s h B i o l o g y . 39: 739-744. Jordan, W. C. and A. F. Youngson. 1992. The use of genetic marking to assess the reproductive success of mature male A t l a n t i c salmon parr {Salmo salar, L.) under n a t u r a l spawning c o n d i t i o n s . J . F i s h B i o l . , 41: 613-618. Katano, 0. 1990. Dynamic r e l a t i o n s h i p s between the dominance of male dark chub, Zacco temmincki, and t h e i r a c q u i s i t i o n of females. Animal Behavior. 40: 1018-1034. Keenleyside, M.H., and Dupuis, H.M.C. 1988. Courship and spawning competition i n pink salmon {Oncorhynchus gorbuscha) . Can. J. Zool. 66: 262-265. Lawrence, W.S. 1987. D i s p e r s a l : an a l t e r n a t i v e mating t a c t i c c o n d i t i o n a l on sex r a t i o and body s i z e . Behav. E c o l . S o c i o b i o l . 21: 367-373. Lima, S. L., and L. M. D i l l . 1990. Be h a v i o r a l d e c i s i o n s made under the r i s k of predat i o n : a review and prospectus. Can. J . Zool. 68: 619-640. Lucas, C. L., A. D. F. Johnstone and I. G. Prie d e . 1993. Use of p h y s i o l o g i c a l telemetry as a method of e s t i m a t i n g metabolism of f i s h i n the n a t u r a l environment. Trans. Amer. F i s h . Soc. 122: 822-833. Maekawa, K. and H. Onozato. 1986. Reproductive t a c t i c s and f e r t i l i z a t i o n success of mature male Miyabe charr, Salvelinus malma miyabei. Env. B i o l . F i s h . 15: 119-129. Magnhagen, C. 1994. Sneak or challenge: a l t e r n a t i v e spawning t a c t i c s i n n o n - t e r r i t o r i a l male common gobies. Anim. Behav., 47: 1212-1215. M e l l a s , E. J . , and J. M. Haynes. 1985. Swimming performance and behavior of Rainbow t r o u t {Salmo gairdneri) and White perch {Morone americana): e f f e c t s of a t t a c h i n g telemetry t r a n s m i t t e r s . Can. J. F i s h . Aquat. S c i . 42: 488-493. Murdoch, S. 1988. Salmonid escapement estimates and data c o l l e c t i o n f o r Kanaka Creek. Prepared f o r Department of Fi s h e r i e s and Oceans, Salmonid Enhancement P r o j e c t s . 50 pp. 97 Neave, F. 1943. Diurnal f l u c t u a t i o n s i n the upstream m i g r a t i o n of coho and s p r i n g salmon. J. F i s h . Res. Board Can. 6: 158-163. Olsen, K. H. and N. R. L i l e y . 1993. The s i g n i f i c a n c e of o l f a c t i o n and s o c i a l cues i n m i l t a v a i l a b i l i t y , sexual hormone status, and spawning behavior of male rainbow t r o u t {Oncorhynchus mykiss) . Gen. Comp. Enddo c r i n o l . 89: 107-118 . Otronen, Merja. 1993. S i z e - r e l a t e d male movement and i t s e f f e c t on s p a t i a l and temporal male d i s t r i b u t i o n at female o v i p o s i t i o n s i t e s i n the f l y Dryomyza anilis. Amin. Behav., 46: 731-740. Power, J. H., and J. D. McCleave. 1980. R i v e r i n e movements of hatchery reared A t l a n t i c salmon {Salmo salar) upon r e t u r n as a d u l t . Env. B i o l . F i s h . 5: 3-13. P r e i d e , I . G. 1980. An analyses of o b j e c t i v e s i n telemetry s t u d i e s of f i s h i n the n a t u r a l environment. B i o t e l e m e t r y : 105-118. Quinn T.P., and C.J. Foote. 1994. The e f f e c t s of body s i z e and sexual dimorphism on the reproductive behavior of sockeye salmon, Oncorhynchus nerka. Anim. Behav., 48: 751-761. Quinn T. P., M. D. Adkison, and M. B. Ward. 1995. Be h a v i o r a l t a c t i c s of male sockeye salmon (Oncorhynchus nerka) under v a r y i n g operating sex r a t i o s . Ethology. Reynolds, J.D., M.R. Gross and M.J. Coombs. 1993. Environmental conditions and male morphology determine a l t e r n a t i v e mating behavior i n T r i n i d a d i a n guppies. Animal Behavior. 45: 145-152. Sandercock, K. 1991. L i f e h i s t o r y of coho salmon. In: P a c i f i c Salmon L i f e H i s t o r i e s . )Ed. C. Groot and L. M a r g o l i s ) . pp 397-445, Vancouver, U n i v e r s i t y of B.C. Press. Sargent, R.C., M.R. Gross, and E.P. van den Berghe. 1986. Male mate choice i n f i s h e s . Animal Behavior. 34: 545-550. Satou, M., A. S h i r a i s h i , T. Matsushima, and N. Okumoto. 1991. V i b r a t i o n a l communication during spawning behavior i n the hime salmon (landlocked red salmon, Oncorhynchus nerka). Journal of Comparative Physiology A. 168: 417-428. 98 Schroder, S.L. 1973. E f f e c t s of d e n s i t y on the spawning success of chum salmon {Oncorhynchus keta) i n an a r t i f i c i a l spawning channel. MSc. Thesis. U n i v e r s i t y of Washington. Schroder, S. L. 1981. The r o l e of sexual s e l e c t i o n i n determining o v e r a l l mating patterns and mate choice i n chum salmon. Ph.D. t h e s i s , U n i v e r s i t y of Washington, S e a t t l e . 274 p. Schroder, S. L. 1982. The i n f l u e n c e of i n t r a sexual competition on the d i s t r i b u t i o n of chum salmon i n an experimental stream. In: E. L. Brannon, Salo E.O. (eds) Salmon and t r o u t migratory behavior symposium, School of F i s h e r i e s , U n i v e r s i t y of Washington, S e a t t l e , pp 275-285. Shapovolov, L., and A. C. T a f t . 1954. The l i f e h i s t o r i e s of the steelhead rainbow t r o u t {Salmo gairdneri) and s i l v e r salmon {Oncorhynchus klsutch) w i t h s p e c i a l reference to Waddell Creek, C a l i f o r n i a and recommendations regarding t h e i r management. C a l i f . Dep. F i s h Game F i s h B u l l . 98: 375p. Shuster, S. M. 1989. Male a l t e r n a t i v e r eproductive s t r a t e g i e s i n a marine isopod crustacean {Paracerceis sculpta) : The use of genetic markers to measure d i f f e r e n c e s i n f e r t i l i z a t i o n success among alpha, beta and gamma males. E v o l u t i o n . 43(8): 1683-1698. Smith, John Maynard. 1982. E v o l u t i o n and the theory of games. Cambridge U n i v e r s i t y Press. Svedang, H. 1992. Observations on i n t e r b r e e d i n g between dwarf and normal a r c t i c charr, Salvelinus alpinus, from Stroa Rosjon, c e n t r a l Sweden. Environmental B i o l o g y of Fishes 33: 293-298. Tautz, A.F. and C. Groot. 1975. Spawning behavior of chum salmon {Oncorhynchus keta) and Rainbow t r o u t {Salmo gairdneri). J . F i s h . Res. Board Can. 32: 633-642. Thorpe, J . E. 1990. V a r i a t i o n i n l i f e - h i s t o r y s t r a t e g y i n salmonids. P o l . Arch. H y d r o b i o l . 37: 3-12. van den Berghe, E. P. 1984. Natural s e l e c t i o n and reproductive success of female coho salmon {Oncorhynchus kisutch) a study i n female competition. MSc. t h e s i s . Simon Fraser 99 U n i v e r s i t y , B. C. 84 pp. van den Berghe, E. P. and M. R. Gross. 1986. Length of breeding l i f e of coho salmon {Oncorhynchus kisutch) . Can. J. Zool. 64: 1482-1486. Webb, J. , and A. D. Hawkins. 1986. The movements and spawning behavior of adult salmon i n the Girnock burn, a t r i b u t a r y of the Aberdeenshire Dee. Scott. F i s h . Res. Rep. No. 40. 42 pp. Webb, J. 1989. The movements of adult A t l a n t i c salmon i n the r i v e r Tay. Sco t t . F i s h . Res. Rep. No. 44. 32 pp. Webb, J. 1990. The behavior of adult A t l a n t i c salmon ascending the r i v e r s Tay and Tummel to p i t l o c h r y dam. Sc o t t . F i s h . Res. Rep. 48, 27pp. Webb, J . 1992. The behavior of adul t salmon {Salmo salar L.) i n the r i v e r Tay as determined by ra d i o telemetry. S c o t t . F i s h . Res. Rep. No. 52. 18 pp. Whitehouse, M.E.A. 1991. To mate or f i g h t ? Male-male competition and a l t e r n a t i v e malting s t r a t e g i e s i n Argyrodes antipodiana {Theridiidae, Araneae) . B e h a v i o r a l Processes. 23: 163-172. Zar, J. H. 1984. B i o s t a t i s t i c a l Analyses. P r e n t i c e - H a l l , New Jersey. 718 p. Zimmerer, E.J., and K.D. Kallman. 1989. Genetic b a s i s f o r a l t e r n a t i v e reproductive t a c t i c s i n the pygmy s w o r d t a i l , Xiphophorus nigrensis. E v o l u t i o n 43: 1298-1307. 100 Appendix P h y s i c a l c h a r a c t e r i s t i c s of Kanaka Creek and two of i t s t r i b u t a r i e s Donovan and Thornvale Creeks. High d e n s i t y of coho spawners observed i n t r i b u t a r y h a b i t a t s . P h y s i c a l Parameters Creek Kanaka Donovan T h o r n v a l e lower upper lower upper lower upper Date 2-Nov 2-Nov 3-Nov 3-Nov 3-Nov 3-Nov *Mean width m (SE) 13.07 (0.4) 7.81 (0.37) 2.39 (0.11) 3.25 (0.1) 2.34 (0.16) 2.11 (0.14) *Mean Depth cm (SE) 27.66 (2.55) 39.38 (4.94) 17.76 (1.29) 17.15 (2.03) 6.79 (1.72) 7.69 (0.67) Temp (oC) 8.5 8 10 10 9.3 9.5 V e l o c i t y (cm/s) 58.3 16.3 66.6 91.1 34.5 16.1 Oxygen (ppm) 10.5 11.2 9.7 10.9 10.3 10.8 T u r b i d i t y (NTU) 3.4 2.5 14.5 11.85 13.2 9.6 Dominant S u b s t r a t e C o b b l e / g r a v e l Bedrock/boulders Sand/gravel G r a v e l G r a v e l C o b b l e / g r a v e l / c l a y R i p a r i a n v e g e t a t i o n Red A l d e r 80t 10S 5S 50* 708 65* Red Cedar 5* 70S 40S 4* 20* Douglas F i r 10» 1* Western Hemlock n 5* Willow 10* 101 Salmon Be r r y 5S 6* 60S 10* 25* 10* None 25* * n = 26 101 

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
https://iiif.library.ubc.ca/presentation/dsp.831.1-0074812/manifest

Comment

Related Items