326 



Fishery Bulletin 98(2) 



500 



400 . 



300 



200 - 



100 . 



o 



T3 



0) 



E 



Q] Coho 



g Great Sculpin 

 □ Buffalo Sculpin 

 Q Staghorn Sculpin 

 Dolly Varden 



500 



400 



300 



200 



100 



1988 



QCoho 



g Great Sculpin 

 [] Buffalo Sculpin 

 Staghorn Sculpin 

 Q Dolly Varden 



1989 



' I I ' ' ' 



April May 



June 



July 



Mean 

 shore 



Figure 4 



catch per set of potential predators of juvenile pink salmon in the 

 areas of Auke Bay, Alaska, 1988 and 1989. 



Growth rates 



Growth ( as a percentage [bwd] ), of tagged and untagged 

 juvenile pink salmon was examined in two periods, 1 

 April to 6 May (early) and 7 May to 16 June (late) in 

 all study years (Table 2). Growth of tagged fish in the 

 early period ranged from 2.93% bwd in 1986 to 4.88% 

 in 1989 and of untagged fish from 1.21% bwd in 1987 

 to 2.10% in 1989. In the late period, growth of tagged 

 fish ranged from 4.82% bwd in 1986 to 6.66% in 1988, 

 and of untagged fish from 2.87% bwd in 1989 to 4.86% 

 in 1988. Tagged and untagged juvenile pink salmon 

 grew significantly slower in the early period than in 

 the late period in all years. 



Growth rates calculated for tagged juvenile pink 

 salmon in any given period in a year were consis- 

 tently higher than the apparent growth rates calcu- 

 lated from the mean weights of samples of untagged 

 pink salmon (Table 2). Continuous recruitment of 



newly emigrated juveniles (fork length <33 mm) into 

 the untagged population caused this pattern. The 

 number of untagged juvenile pink salmon shorter 

 than 33 mm that were captured by beach seine 

 ranged from highs between 59% and 100% in late 

 March each year to below 10% by 20 May of each year 

 except 1989, when they remained at 11% until 12 

 June. Such variations in the number of new recruits 

 and the number of larger fish leaving the nearshore 

 juvenile pink salmon population resulted in a bias 

 for growth rate calculations from untagged popula- 

 tions. Tagged fish provided a more realistic assess- 

 ment of growth in relation to the environment. 



Factors limiting growth 



Fish growth can be limited by low water tempera- 

 tures (Weatherley and Gill, 1995) and low prey abun- 

 dance ( Brant et al., 1992 ). To determine when growth 



