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Fishery Bulletin 97(4), 1999 



indicates that some fishermen with tags did not re- 

 turn them because of resistance to identifying fish- 

 ing locations and because of preconceived ideas and 

 concerns about the significance of the release and 

 recapture site. The extent of a lack of reporting is 

 difficult to quantify and its effect may not introduce 

 bias if nonreported tags have the same geographic 

 distribution as reported tags. 



Advertizing campaigns for the 1994 experiment 

 were much more extensive than those used in the 

 early 1980s. Printed notices covered a larger audi- 

 ence, the experiment was discussed with industry 

 representatives and conducted with their support, 

 interim results were presented, and a more active 

 role was taken by field staff to collect recovered tags. 

 However, the return rate was higher in the 1980s. 

 For example, the return rate in the first 24 months for 

 the 1984—85 Georges Bank experiments was about 

 12.2% compared with 5.5% for the 1994 experiment. 



Fisheries management controls may play a more 

 substantial role in determining the number of recap- 

 tures. Controls may include area closures, restricted 

 seasons, and catch limitations. The Browns Bank 

 area has been closed to fishing during the winter 



Ftecaptures (per rriile) 



Figure 9 



Distribution of adju.sted cod tag recoveries from releases in the Georges 

 Bank (5Zj) area, aggregated by lO-min latitude and longitude squares. 



spawning season for many years. Canadian commer- 

 cial fishing on Georges Bank has been closed between 

 January and May since 1994, and the United States 

 has an extensive closed area covering most of the 

 northeast part of the Bank. These restrictions sub- 

 stantially reduce the possibility of recaptures dur- 

 ing the spawning season. 



The establishment of the International Maritime 

 Boundary in 1984 between the United States and 

 Canada and the associated opinions and concerns of 

 the fishing industry have undoubtedly introduced 

 bias in the tag return rate and perhaps in the re- 

 ported recovery location. It might be assumed that 

 the direction of the bias would tend to support the 

 concept of national ownership of the resource by the 

 fishing industry and that tags recovered at times or 

 locations that appeared to contradict this opinion 

 would be withheld or discarded. Comparison of tag 

 recoveries from the 1984—85 releases with those from 

 the 1994 releases does not show substantial differ- 

 ences in distribution offish. The first period includes 

 the time when response to international boundary 

 change would have been most sensitive and pro- 

 nounced. The second period, more than ten years 

 after the change, might be expected to have 

 reduced concerns by fishermen on tag location. 

 However, the impact of nonreporting bias 

 would be of most concern in evaluating the pro- 

 46 portional spatial distribution of tag recover- 



ies. Bias in reported recapture location is of 

 less concern because fishing activities are 

 monitored and there is limited opportunity to 

 misreport the area of operations. 



Total allowable catches and landings of cod 

 from the Georges Bank area in 1994 declined 

 to less than 50% of the recent ten-yr average 

 and are expected to remain at low levels for a 

 number of years (Hunt and Buzeta, 1996). The 

 impact of reduced catches is accounted for, to 

 some extent, by reduced annual exploitation 

 and its impact on tag-recapture adjustment. 

 However, other changes in the fishery, such 

 as shifts in gear sectors and spatial redirec- 

 tion of effort, may offset this adjustment. 



Even with the need, discussed above, to 

 qualify the interpretation of tagging data, we 

 believe the results of the present study clearly 

 indicate that interchange between the 5Zj,m 

 and 4X cod management units occurs with a 

 net movement from 5Zj,m to 4X. Cod released 

 on Georges Bank exhibited movement outside 

 the 5Z management area onto Browns Bank 

 and the inshore areas of Nova Scotia and the 

 Bay of Fundy. Cod released on Browns Bank 

 also moved to the inshore area of Nova Scotia 



