Authors

Sarah Stelter

Document Type

Internship Report

Publication Date

Fall 2012

Abstract

Red snapper (Lutjanus campechanus) has been classified by the National Marine Fisheries Service (NMFS) as an over fished species since the 1980s. To rebuild depleted stocks, regulations have been established for the commercial and recreational sectors of the fishery. In the recreational fishery those regulations includes: bag limits, seasonal and area closures, the use of venting tools, and size limitations. A source of mortality that is presently unstudied and quantified is depredation, the active feeding off the line of hooked fish of bait or target species by predators. This study aims to give a first look into the issue of depredation in the northern Gulf of Mexico’s red snapper recreational charter industry by use of underwater video to capture depredation and begin to quantify the potentially significant loss of caught red snapper to predators. This study was composed of 27 fishing trips taken off the coast of Destin, Florida from February 2010 through July 2011 on a recreational charter vessel in which 692 sets were filmed using underwater cameras. The majority of the catch, 77%, was comprised of red snapper. Red snapper also accounted for a significantly higher CPUE and depredation rate over all other species. Red snapper had 5.6% of the total hooked species depredated by dolphins and sharks. Dolphins depredated the catch 11 times more than shark species, with dolphins becoming accustomed to the presence of fishing activity with learned behavior for depredating on fish over time and learning from other dolphins how to successfully depredate. When CPUE was tested against CPUE with 5.6% depredation added back in, this result was significantly different. If depredation were not occurring and 5.6% depredation of the catch was caught but not landed then these fish were not accounted for in the quota. This unaccounted loss may affect population abundance estimates and mortality rates for red snapper. Further studies are necessary to fully quantify the extent of depredation in the Gulf of Mexico and will give managers a clearer picture of the depredatory sources of mortality for red snapper.

Comments

Department: MBF

MPS Track: FMC

Location: National Oceanographic and Atmospheric Administration, National Marine Fisheries Service

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