Wigley and Serchuk Spatial and temporal distribution of juvenile Gadus morhua 



603 



Table 3 



Results of Kruskal-Wallis analyses of variance 

 of age-specific cod Gadus morhua distribution 

 by temperature and depth by season, based on 

 data for cod collected during NEFSC bottom- 

 trawl surveys, 1982-86, in the Georges Bank- 

 Southern New England region. NS = not sig- 

 nificant, p>0.05; **highly significant, p<0.01. 



Season 



Age-group Temp. Depth 



Spring 



Autumn 



NS 



(76-92% annually during the period; Table 

 4), suggesting that the proration procedure 

 employed in this study accurately depicts 

 the patterns of landings. 



Age-2 cod dominated commercial landings 

 of scrod in all years except 1984 and 1986, 

 when age-3 fish comprised the majority 

 (Table 5); this exception is due to weak 1982 

 and 1984 year-classes (Serchuk and Wigley 

 In press). Age-1 fish are too small to be 

 caught by the commercial gear until 

 quarters 3 and 4; conversely, age 4-i- fish 

 grow out of the scrod market category and 

 into the next market category after quarter 

 2 (Table 5). Based upon these observations, 

 and the observation above from analysis of 

 survey data that age-3 cod are seasonally 

 segregated from ages 1-2, analysis of 

 juvenile cod distribution from commercial 

 data was confined to age-2 fish. 



The following patterns of age-2 juvenile 

 cod distribution emerged. In quarter 1, 

 juvenile cod were concentrated in the Nan- 

 tucket Shoals region (south of the stepped 

 portion of the boundary between SAR 521 

 and 526) as well as being dispersed generally 

 across the shallower central portions of 

 Georges Bank, primarily in SAR 522 and 

 524 (Fig. 3A). By quarter 2, the area con- 

 centration was north of Nantucket Shoals 

 (in SAR 521), while on Georges Bank there 

 continued to be a dispersed distribution as 

 in quarter 1 (Fig. 3B). In quarter 3, the Nan- 

 tucket Shoals concentration had moved northeastward 

 within SAR 521 to deeper water along the 100 m con- 

 tour of the west slope of the Great South Channel; 

 similarly, juveniles on Georges Bank had formed con- 



centrations along the 100 m contour in SAR 522 (the 

 east slope of the Great South Channel) and 523 (the 

 Northern Edge and Northeast Peak areas; Fig. 3C). 

 By quarter 4, the Nantucket Shoals concentration had 



