Section : Research Article

Published Date : May 19,2013

Lede

Commercial Fishery Catch Characteristics and Population Assessment of the Shortfin Mako Shark (Isurus oxyrinchus) in the Western North

Abstract

Pelagic sharks, an oceanic group of sharks, are an incidental bycatch in many global pelagic longline commercial fisheries, including the U.S commercial longline fishery that operates in the western North Atlantic Ocean. Shortfin mako shark (Isurus oxyrinchus) is one of the only pelagic sharks that have any economic value. Similar to other sharks, the shortfin mako shark is slow-growing, late-to-mature, and has a low fecundity, which makes this species vulnerable to overexploitation. In 2002, the International Union for Conservation of Nature (IUCN) classified the shortfin mako shark as Lower Risk (Near Threatened [NT]) on its annual Red List of Threatened and Endangered Species. Given the current conservation status and the general paucity of data on the status of the shortfin mako shark population, the objectives of this study were to characterize the commercial pelagic longline shortfin mako catch and assess its population in the western North Atlantic Ocean using a simple production model. Commercial data indicated that pelagic longline fishing effort has decreased with time, but most of the fishing effort continued to be in the Gulf of Mexico. Catches of shortfin mako shark have decreased over time, but observer data showed that larger animals were taken in the fishery. Overall, the Schaefer model was generally the least sensitive to varying K values, more sensitive to F values, and the most sensitive to r values.