Mortensen et al : Growth of Oncorhynchus gorbuscha in relation to marine water temperature, secondary production, and survival 331 



The relatively sparse population of potential preda- 

 tors in early spring allow a portion of the juveniles 

 to survive the period of low growth. Growth was 

 strongly related to adult survival within each of the 

 study years; however, this relationship did not hold 

 true between years. 



Growth of fish in the tag groups over all recovery 

 years ranged from 3.4% (8 May 1986 release) to 6.4% 

 (29 April 1988 release). These rates are within the 

 1.5-7.6% range of growth rates previously reported 

 for pink salmon during their initial marine residency 

 (LeBrasseur and Parker, 1964; Healey, 1980). Wil- 

 lette (1996) also observed growth rates of 3.5-5.2% 

 for cwt pink salmon in Prince William Sound. 



Variations in the feeding activity of salmonids is 

 characteristic of opportunistic and broad-spectrum 

 predators, which optimize their food consumption 

 in response to prey density (Parker and Vanstone, 

 1966; Parker, 1969; Ware, 1972; Hunter and Thomas, 

 1974; Godin, 1981). Both epibenthic crustaceans and 



zooplankton were important components of the prey 

 of juvenile pink salmon during their nearshore resi- 

 dence in Auke Bay. In previous studies, harpacticoid 

 copepods, among other epibenthic organisms, have 

 been reported as the primary prey of pink salmon 

 juveniles in nearshore marine habitats ( Healey, 1980; 

 Godin. 1981; Landingham, 1982; Webb, 1991). In 

 Alaska waters, however, planktonic prey often pre- 

 dominate in the early diet of pink salmon (Bailey et 

 al., 1975; Cooney et al., 1981; Sturdevant et al., 1996; 

 Willette, 1996). Some of these differences are due to 

 the types of beaches where juvenile pink salmon are 

 sampled. In studies where harpacticoid copepods are 

 the primary dietary component, the fish are sampled 

 at low-gradient beaches with substantial epibenthic 

 production (e.g. Kaczynski et al., 1973; Godin, 1981; 

 Webb, 1991). Sturdevant et al. (1996) also found 

 that a higher proportion of epibenthic prey was con- 

 sumed by juvenile pink salmon captured on lower- 

 gradient than on steep-gradient beaches. In Auke 



