846 



Fishery Bulletin 97(4), 1999 



for each fish and averaged by 10-cm intervals of re- 

 lease length to give an annual growth rate. 



Results 



Average cod catches per tow, derived from U.S. spring 

 and fall research surveys for 1982-91, are shown in 

 Figure 2, A and B, and indicate widespread distribu- 

 tioh throughout the area with some apparent cen- 

 ters of aggregation associated with banks. Densities 

 and distributions show seasonal variation between 

 the spring and fall. In the spring, distribution (with 

 localized areas of high density) appears to be con- 

 tiguous from Cape Cod, across Georges Bank, to 

 Browns Bank and then farther east and west to the 

 Bay of Fundy. In the fall, densities are lower and 

 there is more apparent geographic isolation. Gavaris 

 et al. (1993) found similar results when comparing 

 seasonal distributions in relation to the 1MB line in 

 the Georges Bank area. The central part of the Gulf 

 of Maine area has relatively low densities for both 

 spring and fall seasons. 



Over 58,000 releases were included in our study 

 of which about 22,300 were in the Gulf of Maine pri- 

 mary study area. The release sites in the Gulf of 

 Maine area, aggregated by ten-min latitude and lon- 

 gitude squares, are shown in Figure 1 and summa- 

 rized by date and unit area in Table 1. Releases by 

 area ranged from about 11,000 in 4Xp (Browns Bank) 

 to only seven in 5Yd. Total recaptures were more than 

 6300 with over 2400 from the Gulf of Maine. Return 

 rate by area varied between 0% and 34% with an 

 average of 9%. Release length ranged from about 

 15 cm to about 140 cm. A relatively high proportion 

 of released fish were >80 cm in the 5Zj area. The 

 majority of released cod were larger than the L-^ ma- 

 turity (-43 cm; see Hunt 1996), with the exception 

 of unit areas 4Xm and 4Xo. 



Observed numbers of recaptures by division of re- 

 lease and recapture for each of "east of 4X," 4X, 5Y, 

 and 5Z areas are shown in Figure 3. Over 9T'/( of cod 

 recaptured from releases east of 4X were also recov- 

 ered east of 4X and, conversely, 74% of fish recap- 

 tured in this area originated from releases east of 

 4X. Further analysis of information on the area east 

 of 4X is required but, in general, movement between 

 this area and the Gulf of Maine appears to be lim- 

 ited. For division 4X, 80% of recaptures from releases 

 in 4X occurred in 4X, with 8% moving east of 4X and 

 12% west to 5Z and 5Y. Of the total recaptures taken 

 in 4X, 50% were from 4X releases, 42% from 5Y re- 

 leases, and 8% from division 5Z releases. In division 

 5Y, 63% of recaptures from releases in 5Y occurred 

 in 4X and of these only 21% occurred in 5Y and 2% 



Average number per tow 

 ^' A spring 



-10 



i 



-26 



70 69 68 67 66 65 



Average number per tow 

 ■' B fall 



yi *-' - .,--.» 



Figure 2 



Mean catch per tow of cod derived from 1982-91 U.S. re- 

 search surveys in the Gulf of Maine area: (A) spring and 

 IB) fall. 



from 5Z. However, of the total recaptures in 5Y, over 

 80% were from 5Y releases and 17% from 4X. The 

 high proportion of recaptures in 5Y from division 4X 

 is probably influenced by the small numbers of re- 

 leases and recaptures as well as the distribution of 

 commercial fishing in the vicinity of the 4X and 5Y 

 boundary. Clark (1996) noted that Canadian land- 



