FISHERY BULLETIN: VOL. 85, NO. 3 



KODIAK 

 ISLAND 



CHIRIKOF I, 



POLLOCK EGG ABUNDANCE 

 Number/10 m 



I 4* I 1-100 

 ^IP >100 



^ 



^ 



^ 



57 OON 



- 56 OON 



- 55 OON 



159 OOW 



158 OOW 



157 OOW 



156 OOW 



155 OOW 



154 OOW 



Figure 6. — Distribution and abundance of walleye pollock eggs, May 1983. 



(Table 2). The means of the catch per 10 m-^ at 

 each time-depth combination expressed as a per- 

 centage of the total catch at that time of day sug- 

 gests a pattern of limited diel vertical migration 

 (Fig. 7). The chi-square test was highly signifi- 

 cant iP < 0.005) indicating that the null hypothe- 

 sis, that the larvae were distributed at each depth 

 in the same proportions among the different 

 times, should be rejected. Examining the relative 

 abundances within each time period, the larvae 

 appeared to be concentrated above 20 m at 0630 h, 

 and at 28-47 m by 1830 h (Fig. 7). They were most 

 evenly distributed in the early afternoon and 



most abundant in the 21-28 m stratum during 

 darkness (2230 and 0230 h) and at 1030 h. The 

 lowest percent abundance at each time period 

 shows a complementary pattern, with relatively 

 small catches at 39-47 m from 0230-1430 h. This 

 pattern was observed on both days during the 

 48-h sampling. 



In summary, it appears that some larvae grad- 

 ually move up in the water column from a depth 

 of 30-50 m in the evening to above 20 m in early 

 morning. They gradually descend during day- 

 time, and are most evenly distributed in the early 

 afternoon. 



508 



