Atlantic Menhaden Seasonal Migration, Survival, and Exploitation Rates during 1966-1969

Atlantic Menhaden Brevoortia tyrannus is an economically and ecologically important forage fish that exhibits seasonal migration along the U.S. Atlantic coast. They are prey for predatory fishes and are targeted by large-scale reduction and bait fisheries. In the mid-60s, the U.S. Bureau of Commercial Fisheries conducted a mark-recapture study, which tagged over one million adult Atlantic Menhaden. Our objectives were to estimate migration, survival, and exploitation rates of adult Atlantic Menhaden using mark-recapture models that could account for both tag loss and tag detection probability. We built a spatially and seasonally explicit dead-recovery model that estimated natural mortality, fishing mortality, and migration probability during 1966-1969. Preliminary estimates of natural mortality were substantially larger than estimated values at the time, while fishing mortality was less than stock assessment estimates. Migration parameter estimates indicated a northward movement of fish during winter and spring and a less pronounced southward movement during fall. The magnitude of southward migration in the winter was less than previously described.  Increased understanding of Atlantic Menhaden movement and natural mortality should improve management of the fishery.