Kinship and social dynamics in juvenile Atlantic salmon and rainbow trout : the adaptive role of kin discrimination

• Main Author: Brown, Grant Edwin
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 1993
• Subjects: Atlantic salmon; Salmo salar
• Online Access: https://research.library.mun.ca/1230/; https://research.library.mun.ca/1230/1/Brown_GrantEdwin.pdf; https://research.library.mun.ca/1230/3/Brown_GrantEdwin.pdf

I conducted a series of experiments designed to examine the regulating mechanisms and the functional value of kin discrimination in two juvenile salmonids: Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss ). The first two studies documented kin discrimination abilites in these species and also determined the possible recognition mechanism responsible for kin discrimination abilities in these species. When given the 'choice', individual salmon and trout fry spent a significantly greater proportion of time in waters conditioned by kin versus non-kin (Chapter 2). When I controlled for familiarity (Chapter 3), individual trout fry spent a significantly greater proportion of time in water conditioned by either familiar (reared together) or unfamiliar (reared apart) kin versus non-kin, but exhibited no significant discrimination between familiar versus unfamiliar kin. These data suggest that these species are capable of kin discrimination based on water-borne chemosensory cues and that direct familiarity is not the recognition mechanism regulating this ability. Support for the phenotype matching hypothesis was found. -- I conducted a third study (Chapter 4) designed to examine the effects of kinship on the territorial defence behaviour of juvenile salmon and trout. Kin groups initiated significantly fewer aggressive interactions, utilized a lower proportion of 'overtly aggressive' behaviour types and defended significantly smaller territories than did non-kin groups in an artificial stream channel. This study suggests the possibility for significant inclusive fitness benefits associated with kin-biased territorial behaviour. -- I examined the effects of varying territory quality on these kin-biased territorial defence behaviour in juvenile rainbow trout in the fourth study (Chapter 5). Food availability and predator presentation rates were altered in order to manipulate territory quality. Kin groups were always observed to initiate significantly fewer aggressive interactions and to defend ...