FISHERY BULLETIN: VOL. 71. NO. 3 



Table 8. — Estimated number of tagged fish recaptured, by area and season, from adult Atlantic 



menhaden released in North Carolina in the fall of 1969. 



[Estimates based on primary magnet tag recoveries.] 



' F indicates fall. 



^ -- indicates no menhaden fishing. 



begins in November and, as the season pro- 

 gresses, fish tagged in more northern areas 

 enter the fishery. The first recoveries from re- 

 leases of the previous summer are from fish 



tagged in North Carolina. Then fish from Vir- 

 ginia, Maryland, Delaware, and New Jersey 

 enter the North Carolina fishery before the end 

 of November. During the first week of December, 

 tags are recovered from fish tagged in Long 

 Island Sound. In 1969 we tagged as far north 

 as Narragansett Bay, R.I., and tags from that 

 area were not recovered in the fall fishery before 

 December 18. Consequently, it appears that the 

 fish enter the North Carolina fall fishery pro- 

 gressively; those from farther north enter last. 



Rates of interchange between fishing areas 

 can be inferred from recoveries of the 1967 and 

 1968 releases. Two important aspects of inter- 

 change between areas have been considered: 1) 

 where did tagged fish recaptured in a particular 

 area come from, and 2) where did fish released 

 in a particular area go? 



To determine the relative contributions of 

 fish from one area to another, it is necessary to 

 either tag in proportion to abundance (with 

 equal tagging survival rates in each area) or 

 to adjust the returns to compensate for dispro- 

 portionate tagging in the different areas. In 

 general we attempted to tag in proportion to 

 abundance, but in practice this is impossible 

 since relative abundances are not known until 

 after the fact of tagging. Consequently, we have 

 attempted to adjust the returns in relation to 

 the achieved density of tags in each area. 



There are several possible approaches to 

 equalizing tag density (number of tags per mil- 

 lion individual fish landed) in the different areas. 

 We examined three approaches for the 1967 

 spring and summer tagging season: 



Figure 2. — Commercial fishing areas for Atlantic menhaden 

 along Atlantic coast of the United States. 



1. Season -average 

 density: 



Total number of re- 

 coveries from fish re- 



726 



