A molecular genetic investigation of the population structure of Atlantic menhaden (Brevoortia tyrannus)

Atlantic menhaden (Brevoortia tyrannus) is an ecologically and economically important species along the U.S. East Coast. As a filter-feeder and key prey fish, it provides a critical link between primary production and larger piscivorous predators, such as striped bass (Morone saxatilis), bluefish (Pomatomus saltatrix), and weakfish (Cynoscion regalis). The commercial fishery for Atlantic menhaden consists of a small bait fishery and a larger reduction fishery. Of the 20 menhaden reduction plants (where menhaden are “reduced” to meal and oil) that were once operating along the U.S. Atlantic coast, only the Reedville, Virginia, facility is currently active. The concentration of fishing effort for Atlantic menhaden in and around Chesapeake Bay has raised concerns among many environmentalists and sport fishermen about the possibility of “localized depletion” of Atlantic menhaden in the area. A potential consequence of localized depletion could be the loss of unique genetic variation within Atlantic menhaden, if there is spatial partitioning of genetic variation (stock structure) within the species. Results of previous analyses of the stock structure of Atlantic menhaden have been discordant. Two populations of Atlantic menhaden, one north and the other south of Long Island, New York, were suggested on the basis of vertebral counts and transferrin allele frequencies (Sutherland, 1963; Epperly, 1989). A molecular genetic investigation of the population structure of Atlantic menhaden (Brevoortia tyrannus)