Length, Weight, and Age Composition of the Menhaden Catch in Virginia Waters1

Abstract

Major features of life history of menhaden (Brevoortia tyrannus) were deduced by examination of samples from commercial purse‐seine and pound‐net fisheries, and collections made by plankton nets, gill nets, and otter trawls. Menhaden are present in Virginia waters throughout the year. Spawning probably takes place in the ocean, and young move into Chesapeake Bay and its estuaries soon after hatching. As they grow, they move back down the estuaries toward the sea, so that, in most seasons, mean sizes of fish are progressively greater in a seaward direction. Few fish older than three years arc taken in the commercial fisheries. The purse‐seine fishery takes about 98 per cent of the total catch, operates from May to October, and exploits primarily fish in their third year of life in spring and early summer, and fish in their second year in late summer and fall. The pound‐net fishery takes principally fish in their second year in spring and early summer, and fish in their first year in late summer and fall. Prior sampling by the pound‐net fishery offers a method of forecasting purse‐seine catches at least a year in advance. Ages of menhaden up to the end of the third year of life may be determined by the length‐frequency method or by reading scales. Validity of the scale method has been established, and there is evidence that two groups of fish, characterized by their size at the time of formation of the first annulus, enter the Virginia fishery. Mean lengths at the end of each calendar year of life are approximately 125, 200, and 230 mm. Mean weights are about 30, 130, and 200 g. Spawning in the Chesapeake region probably is most intense in late fall and the following spring, associated with seasonal waves of emigration from and immigration to Chesapeake Bay. In this region maturity is reached at about one and one‐half years of age.