KENDALL ET AL.: GROWTH OF LARVAL WALLEYE POLLOCK 



O 

 O 



J2 



E 



1200 



C3 



0.600 r 



0.500 



0.400 



1200 



Figure 11. — Numbers of prey (A) and gut fullness (B) of walleye pollock larvae by 

 time of day and depth from the vertical distribution stations, May 1983. 



fied from samples taken with the 253 [xm mesh 

 net (Table 4). Pseudocalanus spp. were generally 

 the most abundant taxon. Abundances of Pseudo- 

 calanus females ranged from 11 m~'Ho a peak of 

 1,398 m'^ at 1515 h on the first day at a depth of 

 47 m. The overall mean abundance of Pseudo- 

 calanus females was 224 m"-^. These females com- 

 prised between 9 and 23*^ of the total zooplankton 

 at all depth strata both during the daylight and 

 darkness (Fig. 12). The highest percent contribu- 

 tion by this stage (22-23%) was during daylight 

 hours at the two deepest strata. Peak abundances 

 usually occurred at depth strata below 25 m. 

 Copepodid stages of Pseudocalanus also reached a 

 peak of 1,890 m"-^ at the same station. These 

 copepodids contributed the greatest percentage 



(21-33%) of the total zooplankton at all depths 

 and times. There were no obvious patterns associ- 

 ated with depth or time of day in either abun- 

 dance or percent composition of the total 

 zooplankton. 



Oithona spp. were abundant in the samples 

 even though they were not collected quantita- 

 tively in the 253 jxm mesh net. The peak abun- 

 dance observed was 1,323 m ■^. Oithona spp. were 

 most abundant in the surface stratum comprising 

 18% of the total zooplankton during the day ver- 

 sus <10% of the zooplankton at deeper strata dur- 

 ing the day and at all depths during the night 

 (Fig. 12). Acartia spp., Neocalanus spp., and 

 Calanus spp. were the only other abundant cope- 

 pods. The Neocalanus spp. and Calanus spp. in- 



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