Estimating Atlantic Menhaden Larval Abundance Along the Atlantic Coast of the United States

Despite experiencing a major decline in both recruitment and juvenile production in the Chesapeake Bay during the 1980s, Atlantic menhaden (Brevoortia tyrannus) supports one of the oldest and largest commercial fisheries on the US east coast. In order to understand the underlying causes of this decline, knowledge of recruitment is essential. Specifically, we wanted to determine if changes in juvenile abundance in the Chesapeake Bay could be attributed to corresponding declines in larval production. We used larval data collected from two large-scale NEFSC ichthyoplankton surveys during 1977-2013 that occurred from Nova Scotia to Cape Hatteras, NC. We corrected the larval abundance data by implementing an age-length key from a larval ingress study in the Chesapeake Bay. Next, we used a generalized linear model to account for potential spatial and temporal biases in sampling collection and develop an unbiased index of larval abundance. We compared our larval index of abundance to juvenile trends in the Chesapeake Bay using a time series analysis. Due to a lack of a direct relationship between larval and juvenile abundance in the bay, we identified critical larval ingression periods and examined other environmental factors influencing larval survival.