76 



Fishery Bulletin 92(1), 1994 



1986 

 nauplii 



500— 



>> 

 U 



g 400-| 



3 

 ST 300 



1*1 200— 



100— 







1986 



rn-i-! — -^ 



50 100 150 200 260 300 



Size ((im) 



C.D.F. 



i 



l 



14- 



13- 



12 



11 



10- 



5 

 4 

 3 

 2 

 1 







50 100 160 200 260 300 



1988 

 eggs 



JL 



60 100 160 200 260 300 



Size (um) 



Figure 8 



Size-frequency distribution of nauplii and eggs. Graph in upper left shows size frequency 

 of nauplii from 1985. Graph in upper right shows the full range of size distributions of 

 nauplii by comparing the cumulative distribution functions (CDF) for the two extremes, 

 1985 and 1986. Size distributions of eggs are shown in the two lower graphs for years 

 with the smallest (1986) and largest (1988) eggs. Note changes in frequencies shown on 

 the various ordinates. 



bongo samplers (Table 2). Based on the average 

 abundance and fecundity (see Methods) of adult fe- 

 male copepods, the approximate contribution of each 

 species to the daily production of NI would be: 

 Pseudocalanus spp., >75% ; Metridia pacifica, 18%; 

 Calanus marshallae, 49r; and Calanus pacificus, 

 <1%. These percentages are useful only for the rela- 

 tive scaling they permit; many factors may influence 

 copepod reproduction rates, and rates of develop- 

 ment and mortality will influence further the total 

 standing stock of nauplii contributed by each spe- 

 cies. These results agree with those of Dagg et al. 

 (1984) with respect to the importance of Pseudo- 

 calanus spp. naupliar production for larval walleye 

 pollock feeding. Our results differ in the greater 

 inferred role of Metridia spp., probably because of 

 the deep waters of the Shelikof sea valley compared 



with the Bering Sea shelf where Dagg and his co- 

 authors worked. The numerous small nauplii <120 

 (im that we sampled are from unknown sources. The 

 abundance and fecundity of M. pacifica suggest that 

 they were significant contributors to populations of 

 planktonic eggs and that Calanus marshallae plays 

 a lesser role. A large number of small planktonic 

 eggs <150-um diameter are not accounted for by the 

 adult female copepods retained by our nets. 



Acknowledgments 



This research was supported by the U.S. National 

 Oceanic and Atmospheric Administration through 

 the FOCI program. We thank J. Schumacher for 

 providing CTD data, M. Canino for sharing unpub- 

 lished data on larval walleye pollock diet, K. 



