Estimating Early Mortality and Implications for Reference Points for the Atlantic Menhaden Stock


Atlantic menhaden, Brevoortia tyrannus, constitute the largest landings, by volume,
along the Atlantic Coast and distribute from Florida to Maine and spawns in coastal waters and uses estuaries as its juvenile nursery habitat. Based on the stock assessment in 2009, overfishing of Atlantic menhaden is occurring. Meanwhile, coastal environments have changed rapidly including changes in temperature, circulations, and lower trophic levels. Understanding how environmental factors affect early life survival, and incorporation into fishery management reference points, is important for improving fisheries management and stock assessment. We propose to use several surveys to estimate early survival and understand mechanisms affecting stock-recruitment relationship for Atlantic menhaden and incorporate these factors into timevarying reference points for management of this stock.
Specifically, we will: 1) develop an individual based population model for Atlantic menhaden and 2) estimate menhaden larvae mortality using the larval data from NEFSC plankton surveys and juvenile menhaden abundance from coast wide beach seine surveys. Our ultimate goal is to incorporate changes in larval mortality into stock-recruitment models and development of time-varying reference points. This work brings together oceanographers and stock assessment scientists from agencies and academia to develop process-based indices, and provides a unique opportunity for scientists to work at the boundary between oceanography and population dynamics to directly contribute to the stock assessment process.