854 



Fishery Bulletin 97(4), 1999 



Figures 8 and 9 provide information on the spatial 

 dispersal of cod tagged in the Browns Bank and 

 Georges Bank areas with adjusted recoveries aggre- 

 gated by 10-min squares and expressed on a per thou- 

 sand basis. Most recoveries were made near the re- 

 spective release site. Wlien movement occurred, a 

 general pattern of dispersal from the release site with 

 a gradient from the tagging site to the edges of the 

 distribution was evident. Intermediate areas of ag- 

 gregation were consistent with the geographic dis- 

 tribution of fisheries effort and associated probabil- 

 ity of recapture. Interchange occurred between re- 

 lease site areas, but the main vector of movement 

 from both sites was towards the northeast. As a re- 

 sult, most long distance recoveries were made in the 



1000 



800 



600 



400 



200 



Released in 4Xp 



/ 



la jj] 



iJll J^ 



JkikD 



4Xm 4Xn 4Xo 4Xp 4Xq 4Xr 4Xs 5Y 5Z 



800 



600 



400 



200 



Released in 5Zj,m 



4th quarter 



- 



I 



1st quarter 



m 



d 



5Zg 5Zh 5Zj 5Zm 5Zn 5Zo 4X 5Y 

 Recapture area by quarter 



Figure 7 



Quarterly distribution of cod tag recoveries from the 

 Browns Bank (4Xpl and Georges Bank (5Zji release areas, 

 aggregated by unit area. 



southwestern Nova Scotia and Bay of Fundy inshore 

 areas, although there was limited movement into the 

 northwestern Gulf of Maine or western Georges Bank 

 areas. 



The two time periods associated with Georges Bank 

 tagging are compared in Figure 10 for the 1994 and 

 1984—85 experiments. The two distributions are simi- 

 lar and both show the majority of cod remaining near 

 the release area; more of the long distance disper- 

 sion occurred into the 4X area than to the west into 

 the inner Gulf of Maine. Similarity in the results from 

 the two time periods indicates some consistency in 

 the northeast vector of movement. However, a higher 

 proportion of cod were recaptured in 4X from the 1994 

 experiment (559f ) compared with the earlier releases 

 (42%). As noted above, the reduced U.S. commercial 

 fishery in the area west of the 1MB since 1995 also 

 reduced the probability of tag recaptures from the 

 1994 experiment in this area. 



The distribution of recaptures and elapsed time 

 for the February and March releases for unit areas 

 4Xp (Browns Bank) and 5Zj (Georges Bank) are 

 shown in Figure 1 1 . The majority of returns in both 

 areas occurred in the first 24 months after release, and 

 the maximum time at large was 87 months (Table 4), 

 but the overall average of time at large was less than 

 8 months. Many fish were recaptured in the first 

 month after release, probably before postspawning 

 dispersion had occurred. Maximum distance trav- 

 elled was over 620 km and the mean distanced trav- 

 elled was 60 km. Substantial numbers of cod moved 

 hundreds of kilometres, indicating that cod can sur- 

 vive the stress of tagging and are capable of long dis- 

 tance movements. A strong seasonal pattern, consis- 

 tent with the seasonal nature of the commercial fish- 

 ery, is evident. The fishery on Browns Bank is typi- 

 cally year round, with peaks late spring and sum- 

 mer (Clark, 1996), and on Georges Bank, the fishery 

 typically opens in June (Hunt and Buzeta 1996). The 

 seasonal peaks in recaptures (4—6, 16-18, etc. months 

 after February releases! coincides with the commer- 

 cial fishing activity. 



Length at the time of recapture was available for 

 a relatively small proportion of recaptures. For these 

 samples, the net increase in length and elapsed time 

 was used to calculate a specific growth rate, ex- 

 pressed as annual rate, for each unit area. Results 

 are given in Table 5 for 10-cm length-at-release in- 

 tervals but sample size was small for all but the 4Xp, 

 4Xs, and 5Zj areas. The calculated annual growth 

 rates indicate differences between areas and follow 

 an expected pattern of decrease as the length at re- 

 lease increases. Of these three areas, the Georges 

 Bank area had the fastest growth with an annual 

 increase of about 19 cm for cod released as 40-cm 



