Historical reconstruction of Gulf of California shark fishery landings and species composition, 1939-2014, in a data-poor fishery context

The Gulf of California (GC) is one of the most historically important regions in Mexico for shark fisheries. However, detailed historical shark landings are not available, making it difficult to plan adequate management strategies. This study analyses historical trends in GC shark fishery landings in a data-poor environment to establish a baseline for future research and assessments. The total shark landings for the artisanal fishery from 1939 to 2014, middle-size vessel fishery landings for the 1988-2014, and species composition from 1960 to 2014 were estimated, and we assessed the uncertainty inherent in the data sources and subsequent analyses. Thirty-eight shark species were identified in the GC artisanal fishery, of which Mustelus spp., Sphyrna lewini, Rhizoprionodon longurio, Squatina californica, Carcharhinus falciformis, Sphyrna zygaena, and Carcharhinus limbatus were the taxa with the greatest landings. A noticeable decline in landings was observed for Carcharhinus leucas, Nasolamia velox, Negaprion brevirostris, Sphyrna spp., Carcharhinus altimus, Carcharhinus obscurus, Galeocerdo cuvier, Carcharhinus porosus, Triakis semifasciata, and Carcharhinus brachyurus. Landings of the pelagic sharks Prionace glauca, Alopias pelagicus, and Isurus oxyrinchus increased after 1986, mainly due to the development of the middle-size vessel fishery. The history of GC shark fisheries and implications for management of sustainable shark fisheries are discussed.