Hunt et al ; Movement of Gadus morhua in the Gulf of Maine area 



847 



100 



75 



c 



B 50 



Q. 



25 



East of 

 4X 



By Division 

 ^/ of recapture 



4X 



5Y 



5Z 



I U U J JiJL . 



Division 



Figure 3 



Percent of cod tag recoveries by NAFO Division of release (solid bar) and 

 Division of recapture (pattern bar, based on 1000 releases I for divisions 4X, 

 5Y, 5Z, and the area east of 4X. 



ings from the 5Y area near the 4X-5Y boundary are 

 considered part of the 4X fishery and therefore were 

 included in our 4X stock assessment. In division 5Z, 

 77% of cod released in 5Z were recaptured in 5Z and 

 21% were recaptured in 4X. Of the total recaptures 

 in division 5Z, 81% were from 5Z releases and most 

 of the movement out of the area occurred to the north- 

 east (15%), towards division 4X. 



The annual percent exploitation rate of cod by 

 management area (4X, 5Y, 5Z) is summarized in Fig- 

 ure 4 for the 1980-97 time period. Reported land- 

 ings by unit area showed considerable variation but 

 proportions were relatively stable over time. In divi- 

 sion 4X, unit area 4Xo accounted for about 38% of 

 the 1980-97 total landings and unit area 5Yd for 

 about 40% of the 5Y total. In subdivision 5Ze, unit 

 areas 5Zg(30%) and 5Zj (40%) dominated, represent- 

 ing the U.S. and Canadian fisheries, respectively. The 

 derived recapture adjustment factors, standardized 

 to a maximum of 1.00, are given in Table 2 for each 

 year and unit area. Annual factors ranged from 0.02 

 to 1.00, meaning that about 100 recaptures from a 

 unit area with high landings and exploitation were 

 proportionally equivalent to about two recaptures 

 from a unit area with low landings and exploitation 

 rate. 



The effect of weighting tag recoveries to account 



for fishing effort is shown in Figure 5 for releases in 



the Browns Bank area. Weighted recoveries decrease 



^the apparent extent of movement to 4Xo and 5Zj, 



because of their relatively high landings and exploita- 







808284868890929496 

 Year 



Figure 4 



Reported percent exploitation rate of cod by the 

 commercial fishery in management areas 4X, 5Y, 

 and .5Z for 1980-97. 



tion rates, and increases the contribution of 4Xp recov- 

 eries. Similar effects are seen for other unit areas. 



Table 3 provides a detailed summary of recaptures 

 by unit area of release and recapture partitioned into 

 <12 months elapsed time from release and the total 

 number of recaptures. The observed number of tag 

 returns, the number adjusted by unit area landings, 

 and the percent of total adjusted number are shown. 

 The percent of recaptures reported is based on only 

 those released and recaptured in the Gulf of Maine 



