PRELIMINARY ANALYSES OF ATLANTIC MENHADEN, 



BREVOORTIA TYRANNUS, MIGRATIONS, POPULATION 



STRUCTURE, SURVIVAL AND EXPLOITATION RATES, AND 



AVAILABILITY AS INDICATED FROM TAG RETURNS 



Robert L. Dryfoos, Randall P. Cheek, and Richard L. Kroger' 



ABSTRACT 



Over 1 million adult Atlantic menhaden, Brevooriia tyranmis, were tagged from Long Island 

 Sound to Florida between 1966 and 1969. Tag recoveries indicate these fish migrated north- 

 ward in spring and early summer and southward in fall. As the fish grew older and larger, 

 they also migrated farther northward each spring. Calculation of rates of interchange 

 between fishing areas indicated that 21% of the recoveries from fish released in Chesapeake 

 Bay in 1967 and 1968 accounted for 72% of the catch of tagged fish 1 yr later in New York, 

 and New Jersey. 



Preliminary estimates of population parameters were made from tag-recovery and catch 

 data. Survival rates determined yearly from ratio of recoveries, however, varied due to 

 fluctuations in availability. Annual survival rates averaging 0.23 were calculated with Robson- 

 Chapman catch curve analysis and age composition of catch methods. From tag recoveries, 

 exploitation rate was estimated to be 50%, instantaneous fishing mortality rate (F) was 0.95, 

 and instantaneous natural mortality (M) was 0.52. Tag returns also indicated that significant 

 fluctuations in availability of Atlantic menhaden occurred in Chesapeake Bay. 



Menhaden, genus Brevoortia, are distributed 

 along the Atlantic and Gulf coasts of the United 

 States and constitute the source of the largest 

 U.S. fishery by weight. Prior to 1966 knowledge 

 of population structure and migrations was 

 determined by analysis of meristics, age and 

 size composition and catch-effort data. In the 

 summer of 1966, the Bureau of Commercial 

 Fisheries (now the National Marine Fisheries 

 Service), Beaufort, N.C., began tagging Atlantic 

 menhaden, Brevooirtia tyrannus, to obtain direct 

 information about population structure, move- 

 ments, growth, and survival. In 1967, the pro- 

 gram was expanded to encompass the Atlantic 

 fishing areas from New York to Florida. Through 

 1969 a total of 1,066,357 adult menhaden were 

 tagged with an internal ferromagnetic tag and 

 202,943 were recaptured. In 1969 we began 

 tagging juvenile Atlantic menhaden and adult 

 Gulf menhaden, B. patroinis;, and reduced efforts 

 to tag adult Atlantic menhaden. This paper 



' Atlantic Estuarine Fisheries Center, National Marine 

 Fisheries Service, NOAA, Beaufort, NC 285 16. 



Manuscript accepted November 1972. 

 FISHERY BULLETIN: VOL. 71, NO. 3, 1973. 



describes the results of Atlantic menhaden tag- 

 ging and recovery from 1966 through 1969. 



TAGGING METHOD 



Preliminary experiments were conducted at 

 the laboratory, Beaufort, to determine the best 

 method of tagging menhaden. After experiment- 

 ing with several sizes of internal ferromagnetic 

 tags for menhaden larger than 100-mm fork 

 length, we selected a rectangular stainless steel 

 tag with rounded corners, 14.0 by 3.0 by 0.5 mm, 

 identified with a prefix letter and five numbers 

 (Carlson and Reintjes, 1972). From subsequent 

 experiments, Kroger and Dryfoos (1972) found 

 that clean untreated tags were shed less than 

 tags treated with a germicide. Tags were also 

 shed less when inserted anteriorly rather than 

 posteriorly into the body cavity. Tagging guns, 

 manufactured by Bergen-Nautik, a Norwegian 

 firm, were selected over the scalpel-forcep meth- 

 od of insertion because they are safer to use in 

 the field and increase the speed of tagging with- 

 out increasing mortality or tag shedding. 



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