| This study examines the role of energy as a limiting resource in the regulation of demersal juvenile fish populations. In situ time and energy budgets of daily activities were constructed for cunner (Tautogolabrus adspersus), a common temperate reef fish, in St. Margarets Bay, NS. Maximum O;No particular energetic advantage was offered by any of 4 available habitat types (reef, cobble, seagrass, sand), and cunner showed no evidence of microhabitat selection at or following settlement. Instead, differential predation pressure resulted in variation of recruitment success among habitats. Predators were less successful at capturing newly settled cunner in topographically complex habitats (reef and cobble), and survival was highest in those habitats. Growth rates of 0+ cunner also differed among habitats but was highest in seagrass beds. Thus, 0+ cunner face trade-offs between energy gain (growth) and predation mortality. Mortality of cunner was size-dependent and growth rates of individual fish may therefore be good predictors of their potential survival. Individual growth rates were correlated with the scope for activity remaining after the metabolic costs of foraging were met. Thus, genetic techniques that focus on the heritability of growth processes might be useful predictors of survival of juvenile demersal fishes. |
