Estimating Stock Composition of Anadromous Fishes from Mark–Recovery Data: Possible Application to American Shad

Information on the stock composition of mixed‐stock fisheries is often needed to develop management regulations for anadromous fishes. Although several methods can be used to infer stock composition, marking studies have long been identified as a promising approach. Hatchery‐reared larval American shad Alosa sapidissima are marked with a river‐specific mark and released in stock enhancement programs along the U.S. East Coast. We describe and apply a mark–recovery method for inferring the proportion of the catch in a mixed‐stock fishery that originates from a particular river. The method is based on comparing the proportion of the mixed‐stock catch with marks from the river with the proportion of the fish returning to the river with marks. We explore the utility of using mass marking of hatchery‐reared American shad larvae with tetracycline to determine the stock composition of mixed‐stock fisheries of American shad in Virginia. Our analysis focuses on the impact of the former Virginia coastal ocean fishery on fish produced in the James and Pamunkey rivers, Virginia, and on the impact of bycatch in Chesapeake Bay pound nets on Susquehanna River American shad. Our results suggest that the coastal ocean fishery harvested relatively small proportions of the James and Pamunkey River stocks and that few American shad captured in pound nets sampled in Chesapeake Bay were from the Susquehanna River system.