FISHERY BULLETIN: VOL. 85, NO. 3 



covering the 1955-68 fishing seasons, was pre- 

 pared by Henry (1971). Applying virtual popula- 

 tion methods (number of fish alive that will be 

 caught in the future (Ricker 1958)) to landings 

 from 1955 to 1969, Schaaf and Huntsman (1972) 

 conducted additional analyses of the population 

 dynamics of this resource. Stock status was again 

 examined with production models using adjusted 

 effort and landings through 1973 (Schaaf 1975a). 

 Population dynamics and potential yield of At- 

 lantic menhaden were further examined by 

 Schaaf (1979), using estimates of numbers landed 

 through the 1976 season; he also employed cohort 

 analysis with Pope's (1972) approximation and 

 the Leslie matrix (after Leslie 1945). In response 

 to a request from the State/Federal Fishery Man- 

 agement Program, Atlantic Menhaden Scientific 

 and Statistical committee, a population dynamics 

 subcommittee was formed (Federal, state, and in- 

 dustry membership). Their report (ASMFC^) con- 

 tained an indepth stock assessment (conducted by 

 the Southeast Fisheries Center (SEFC) Beaufort 

 Laboratory, NMFS) based on landings data 

 through the 1977 season, and was the basis for 

 the Atlantic menhaden management plan 

 adopted by the ASMFC (ASMFC 1981). A com- 

 puter simulation model of the fishery was devel- 

 oped in an independent analysis and was based on 

 the 1965 through 1978 seasons (Reish et al. 1985; 

 Ruppert et al. 1985). The general concensus of the 

 earlier studies (Henry 1971; Schaaf and Hunts- 

 man 1972; Schaaf 1979; ASMFC fn. 4) was that 

 the Atlantic menhaden stock was being overex- 

 ploited and concern was expressed regarding the 

 reduced spawning stock and/or the high rate of 

 harvest of immature fish. 



The primary objective of this report is to evalu- 

 ate the stock status of Atlantic menhaden 

 through the 1981 season. The more recent 1970- 

 78 fishing seasons are emphasized, notably in 

 presentations of yield per recruit. Effort, land- 

 ings, and biological sampling data from 1955 

 through 1981 are used to estimate historic popu- 

 lation sizes, age-specific rates of fishing mortal- 

 ity, actual and potential fishery yield, and to ex- 

 amine the spawner-recruitment relationship. 



The secondary objective is to determine what 

 historical series of events led to recent conditions 



4ASMFC (1980). Report of the Atlantic Menhaden Population 

 Dynamics Subcommittee to the Atlantic Menhaden Scientific 

 and Statistical Committee on the status of the Atlantic men- 

 haden stock and fishery. Unpubl. Rep., 68 p. Atlantic States 

 Marine Fisheries Commission, 1717 Massachusetts Ave., N.W., 

 Washington, D.C. 20036. 



in the fishery. This objective can be reasonably 

 met by examining the geographic patterns of har- 

 vesting rates and the relative amount of effort 

 expended in each geographic area. 



The final objective is to generate some informa- 

 tion on the relative abundance and age structure 

 of the menhaden stock during the earlier, pre- 

 sampling period of 1940-54. This is accomplished 

 by comparing, with inferences, the geographic 

 patterns of harvest and effort distribution from 

 the time period with port sampling data (and thus 

 estimates of age-specific exploitation rates) to the 

 patterns of an earlier period when only landings 

 and effort data are available. 



OVERVIEW OF LIFE HISTORY AND 

 STOCK STRUCTURE 



Hypotheses of the seasonal distribution and mi- 

 gration patterns of adult menhaden were formu- 

 lated from observations of fish schools (June and 

 Reintjes 1959; Roithmayr 1963) and analysis of 

 age-length distributions (Nicholson 1971b). 

 These hypotheses were later supported by results 

 of tagging studies (Dryfoos et al. 1973; Nicholson 

 1978). Much of the population is believed to over- 

 winter south of Cape Hatteras to northern Flor- 

 ida, and in late winter begins moving north. By 

 summer, adult menhaden are normally found in 

 dense schools in open coastal waters, bays, and 

 sounds from northern Florida to Maine. These 

 fish schools are stratified by age and size, with the 

 average length and weight increasing with in- 

 creasing latitude. In September, the most 

 northerly portion of the population begins a 

 southerly movement. During November, most of 

 the adult population that summered in waters 

 north of Chesapeake Bay move south around 

 Cape Hatteras. These larger fish are followed in 

 early December by a southward migration of 

 young of the year that have emigrated from estu- 

 arine systems north of Cape Hatteras. 



Atlantic menhaden spawning occurs to some 

 degree during virtually the entire year, but not 

 over the entire range at any given time. Evidence 

 for this comes from an ovarian maturation study 

 (Higham and Nicholson 1964) and observed dis- 

 tributions of menhaden eggs and larvae on the 

 continental shelf (Reintjes 1969; Chapoton^; 

 Kendall and Reintjes 1975; Judy and Lewis 



SChapoton, R. B. 1972. On the distribution of Atlantic 

 menhaden eggs, larvae, and adults. Unpubl. manuscr., 76 p. 

 Southeast Fisheries Center Beaufort Laboratory, National 

 Marine Fisheries Service, NOAA, Beaufort, NC 28516. 



570 



