Abstract
Elasmobranch species composition and spatiotemporal variability can often be characterized from landing surveys of local fisheries, with important management implications. In the present study, we describe the elasmobranch landing composition of 4 major artisanal fishing ports in northwestern Baja California, Mexico. Sampling was conducted opportunistically between 1995 and 2010 and included an effort of 684 fishing days. Species composition was gear-dependent and varied with the fishing area, with thresher sharks (Alopias vulpinus) and spiny dogfish (Squalus suckleyi) dominating the catches landed by coastal gill net fisheries, and blue sharks (Prionace glauca) and shortfin mako sharks (Isurus oxyrhinchus) dominating the catches landed by the offshore longline fishery. Size-structure analysis indicated that catches were composed primarily of juveniles for most species, although the catch of mature soupfin sharks (Galeorhinus galeus) increased in longline fisheries during the winter. The results indicate that minor regional differences in elasmobranch species composition occur along the Pacific coast of Baja California and are most likely related to regional oceanographic or habitat differences. The results of this study may form the basis for future efforts to monitor species composition changes over time, to more completely assess elasmobranch populations.
Highlights
Species composition was gear-dependent and varied with the fishing area, with thresher sharks (Alopias vulpinus) and spiny dogfish (Squalus suckleyi) dominating the catches landed by coastal gill net fisheries, and blue sharks (Prionace glauca) and shortfin mako sharks (Isurus oxyrhinchus) dominating the catches landed by the offshore longline fishery
The results indicate that minor regional differences in elasmobranch species composition occur along the Pacific coast of Baja California and are most likely related to regional oceanographic or habitat differences
The present study describes the species composition and characteristics of landings made by the artisanal elasmobranch fisheries in northwestern Baja California (BC)
Summary
In Baja California (BC), monitoring deficiency is primarily due to the remoteness of many fishing villages Another major problem is the lack of knowledge regarding the species composition of landed catches. The artisanal fisheries of the southern portion of the peninsula have been described by Cartamil et al (2011) and Ramírez-Amaro et al (2013) Both studies described the seasonal species composition of catches and characterized the fishing effort. Studies like these provide important data needed for the management of artisanal fisheries, which are typically data limited. For the west coast of Baja California Sur, Ramírez-Amaro et al (2013) found significant differences in the composition and abundance of elasmobranch species that were related to the biogeographic provinces in the sampling area. The results from previous studies (Bizarro et al 2009a, 2009b, 2009c; Smith et al 2009; Cartamil et al 2011; Ramírez-Amaro et al 2013) and those obtained in this study are important for designing region-specific fishery management plans and may form the basis for future monitoring and population assessment efforts
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