FISIIKKY Hl'LLKTIN: VOL. 86, NO. 4 



Table 4. — Food of adult Sebastes mystinus relative to near-surface plankton during downwelling episodes of fall. 



n = 6. 



with the other tables and figures, but the combina- 

 tions obscure the great variation in feeding condi- 

 tions at this time of year. For example, taxa of the 

 major food categories listed in Table 5 were numer- 

 ous in the diet and plankton only during the two 

 sampling sessions in February and March of 1979. 

 Of the 14 fish collected at those times, all but one 

 was well fed (x no. prey = 26.7), with the excep- 

 tion being a pregnant female whose gut was empty. 

 Thaliaceans dominated on these occasions, both in 

 the diet and in the plankton, and hyperiid amphi- 

 pods, Vihilia spp. (which are parasites of thaliaceans 

 (Laval 1980)), were similarly abundant. In contrast, 

 the collecting session of January 1980 indicated 

 there were more zooplankters in the water column, 

 but that they were exceptionally small. The plank- 

 ton collection took 1,488 zooplankters (compared 



with 109 and 715 in the two 1979 collections), but 

 only 2% were of species that occurred as large as 

 2 mm (compared with 86% in 1979). That these small 

 zooplankters were unsuitable as prey of adult S. 

 mystinus is implicit in the fact that of 16 fish col- 

 lected, only 3 contained food— all of it the alga Por- 

 phyra sp. (The other 13 represented 76% of all fish 

 with empty guts in the winter collections.) Signif- 

 icantly, of the taxa identified as food of adult 

 S. mystinus during the winter (Table 5), only one, 

 the calanoid Calanus pacificus, was represented in 

 the January 1980 plankton collection. Conditions 

 were intermediate during the sampling session of 

 January 1981, when some of the Usted food taxa 

 occurred in both diet and plankton (though in 

 reduced numbers) and five of eight fish sampled con- 

 tained food. 



734 



