Metabolic rate, territoriality and life-history strategies of juvenile Atlantic salmon (Salmo salar L.)

• Main Author: Cutts, Christopher John
• Format: Thesis
• Language: English
• Published: 1996
• Subjects: Atlantic salmon; Salmo salar
• Online Access: http://theses.gla.ac.uk/71713/; https://theses.gla.ac.uk/71713/1/10391351.pdf; https://eleanor.lib.gla.ac.uk/record=b1659979

The relationships between relative standard metabolic rate, aggression, territoriality, growth and subsequent life-history strategies were studied in juvenile Atlantic salmon. In order to do this a method of calculating mass-independent relative standard metabolic rates is presented. This procedure involved using individual deviations from allometric predictions of standard metabolic rate based on body size (termed residual standard metabolic rate). As in a previous study, it was found that salmon with higher relative standard metabolic rates were more likely to acquire dominance, in both pairs and groups. However, fish with higher standard metabolic rates appeared to have smaller metabolic scopes within which they had to carry out dominance-acquiring costly activities such as aggression, although fish with higher standard metabolic rates did indeed acquire dominance through greater aggression. Fish with higher standard metabolic rates, although having a higher cost of maintenance, were found to have a lower feeding motivation, possibly because they had a smaller metabolic scope and movements associated with foraging are themselves energetically costly. Therefore it appears that juvenile salmon with high standard metabolic rates and a limited metabolic scope opt to be more aggressive and thus acquire dominance and a feeding territory at the expense of higher foraging rates, since both behavioural strategies are energetically costly. It was also found that in an environment with little food, fish with high standard metabolic rates grew less well than predicted given their position in an artificial stream than conspecifics with lower costs of maintenance. This indicates a potential cost of a high standard metabolic rate. There is a temporal component to acquisition of territories since juvenile salmon emerge from gravel redds over several days. Through this 'prior residence' effect, fish introduced into a new environment first were more likely to acquire territories than later-arriving conspecifics. First-arriving ...