Stock Assessment of the Lemon Shark off the Southeast United States

Abstract

AbstractThe Lemon Shark Negaprion brevirostris is a large coastal shark that commonly occurs in the shallow nearshore waters of the tropical western Atlantic Ocean. There are conservation concerns for this species due to fisheries exploitation, low productivity, anthropogenic disturbance at nursery sites, and the depleted status of other large coastal sharks, but no quantitative assessment of Lemon Shark stock status is available. We synthesized available data to develop a stock assessment of the Lemon Shark in the western North Atlantic. All information on stock identity was considered to define a fishery management unit off the southeastern United States. Stock abundance and trends in fishing mortality were estimated from 1981 to 2017 using a Bayesian state–space surplus production model. The model incorporated prior knowledge of Lemon Shark demography, catches, and a combination of 11 indices of abundance. Seven model configurations that fit the data well and produced plausible estimates were used to evaluate the sensitivity of posterior estimates to assumed priors and data decisions. Results suggested that Lemon Shark stock abundance has been relatively stable since the mid‐1990s, with some estimates of prior depletion. Estimates of relative fishing mortality indicate earlier periods of overfishing, with a decrease in fishing mortality since the early 2000s. These estimates of population trends provide information for future fisheries management and conservation.