The Espiritu Santo Island as a critical area for conserving batoid assemblage species within the Gulf of California

The Espiritu Santo Island (ESI) has the highest elasmobranch richness among the Gulf of California islands, exemplifying its importance for conservation. In the present study, we assessed the temporal variation of the batoid assemblages captured in the southern ESI. Using the monthly artisanal fishing fleet catch data between 2013 and 2015, we applied three methods to evaluate changes in diversity: descriptive (i.e., richness, dominance, evenness, and Shannon–Wiener index), taxonomic diversity, and functional diversity. Four orders, ten families, ten genera, and 15 species were identified. Mobula munkiana, Hypanus dipterurus, Narcine entemedor, and Rhinoptera steindachneri were the most numerically abundant (dominant) during the study period. The Biological Values Index of these species indicated temporary changes mainly attributable to sea surface temperature. Diversity and average taxonomic distinctiveness values were high, indicating stability in the batoids assemblage assessed. Further, we identified nine functional groups classified mainly into two life history types, benthic and pelagic. The former group was characterized as having small- to medium-sized species and circular and oval body shape with preferences to remain buried or on sea bottom. The second group was formed by large–body size species and rhomboid body shape with high motility in the water column and with migrations. The ESI community of batoids has a stable taxonomic structure over time, whose functional groups have adapted to the ESI environmental conditions and available resources. This study confirms and highlights the importance of ESI as a critical site for these batoid species within the Gulf of California and thus their conservation.