Factors that influence discarding in the Gulf of Mexico commercial grouper-tilefish IFQ reef fish fishery

Abstract

Factors potentially affecting fish discarding were evaluated for species managed under the Gulf of Mexico grouper-tilefish individual fishing quota (GT-IFQ) program. Thirteen commercially important species are managed under the GT-IFQ program. Some of the more commonly caught species in the program include red grouper (Epinephelus morio), gag (Mycteroperca microlepis), speckled hind (Epinephelus drummondhayi), golden tilefish (Lopholatilus chamaeleonticeps), and blueline tilefish (Caulolatilus microps). It is necessary to determine why discards are occurring to develop a future discard mitigation strategy. Logistic models were constructed using data from the Southeast Fisheries Science Center’s (SEFSC) Reef Fish Observer Program (RFOP) with covariates of fish length, available allocation, gear type, calendar year quarter, and year to infer reasons for discarding. The results from RFOP models in conjunction with self-reported discard information from the SEFSC Supplemental Discard Logbook program determined that discarding due to fish length selection, not related to minimum a size limit, is occurring for golden tilefish, speckled hind, yellowedge grouper (Epinephelus flavolimbatus), and snowy grouper (Hyporthodus niveatus). Other dynamics such as multi-species quota discarding are likely responsible for discards of blueline tilefish. Based on the results of the study, potential changes to the GT-IFQ program such as additional flexibility measures were identified as potential management strategies for decreasing discards. A similar approach to inferring why discarding is occurring could be used in the other regions for more effective management promoting long-term sustainability of valuable fisheries.