fall fishery. Assuming that the two groups of 

 fish belong to essentially the same stock, it 

 would appear from the decrease in catch per 

 unit of effort and increases in mean lengths 

 and weights of fish at each age that a de- 

 crease in the abundance of older age groups 

 had occurred over the past several years. 



schools which in previous seasons provided 

 good catches off southern Long Island in 

 September and October failed to appear. 

 Catches in the North Atlantic Area were 

 sporadic through the season. In the North 

 Carolina fall fishery, above-average avail- 

 ability of fish and fair weather were respon- 

 sible for a near-record catch. 



SUMMARY 



1. This is the fourth in a series of reports 

 which summarizes and discusses data re- 

 garding the age composition, size, and 

 sex ratio of Atlantic menhaden (Brevoortia 

 tyrannusj caught by the purse seine fishery 

 during the 1958 fishing season. The data 

 were obtained from a coastwise catch- 

 sampling program for purposes of continu- 

 ing studies on the biology, structure, and 

 dynamics of the Atlantic menhaden popula- 

 tion. 



2. The purse seine catch, 540,000 tons, 

 declined for the second successive year and 

 was the smallestinthepast 4 years; 462,000 

 tons were landed in the summer fishery and 

 78,000 tons in the fall fishery. A total of 

 24,545 purse seine sets represented a 

 decrease of 22 percent from that in 1957. 

 Catch per set was 22 tons, compared to 20 

 tons in 1957. The greatest portion of the 

 catch was taken in the Middle Atlantic Area 

 (43 percent) and the smallest, in the North 

 Atlantic Area (6 percent). 



3. In the South Atlantic Area, summer catches 

 off Florida were the smallest in 10 seasons, 

 while off the Carolinas, schools were 

 numerous, and heavy catches were recorded 

 during June and July. Although fish were 

 scarce over most of this area in August, 

 several large, migratory schools which ap- 

 peared off Cape Lookout in September pro- 

 vided good late-summer catches. Except for 

 the slow start and interruption by a hurri- 

 cane in August, the summer fishery in 

 Chesapeake Bay area was productive 

 throughout. Poor catches were produced at 

 both ends of the fishing season in the 

 Middle Atlantic Area, but heavy landings 

 were made during mid- summer. The large 



4. Two noteworthy variations in the distribu- 

 tion of fishing activities included (1) a 

 decrease in the number of sets at both ends 

 of the fishing range and (2) offshore exten- 

 sion of fishing in the Middle Atlantic Area. 



5. The 1956 year class (age-2 fish) dominated 

 the catch (61 percent) with a contribution of 

 1.7 billion fish. This was the largest 

 contribution at age 2 by recent year classes. 

 This year class was the most abundant one 

 in the summer catches from Chesapeake 

 Bay northward. In the South Atlantic Area, 

 fish of the 1957 year class (age 1) were 

 most numerous in the summer fishery, 

 while in the fall fishery off North Carolina, 

 those of the 1958 year class (age 0) were 

 most numerous; however, in both fisheries, 

 the 1956 year class accounted for the 

 greatest share of the catch by weight. There 

 was a reduction in the number of fish con- 

 tributed by older year classes. 



6. Fish of the dominant 1956 year class were 

 shorter and, in general, lighter than those 

 of the previous three year classes at the 

 same age. There was a tendency for fish in 

 the older age groups to be slightly larger 

 than those of comparable ages in previous 

 seasons. 



7. A north-south cyclic migration and isolation 

 of the summer stock in the South Atlantic 

 Area were hypothesized on the basis of 

 length-age datr' collected during successive 

 fishing seasoHii. 



ACKNOWLEDGMENTS 



We wish to acknowledge the assistance of 

 the reduction plant owners and operators who 

 provided space and facilities for processing 



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