Diversity and conservation of Chondrichthyes in the Gulf of California

This updated checklist of chondrichthyans from the Gulf of California (GC) with notes on zoogeography, conservation status, and commercial value includes 2 subclasses, 14 orders, 31 families, 55 genera, and 106 species. Euselachii (Batomorphi 44.3% and Selachii 51.8%) is the most diverse subclass (13 orders, 29 families, 53 genera, and 102 species). The order Carcharhiniformes (4 families, 16 genera, and 36 species) and Myliobatiformes (6 families, 11 genera, and 24 species) represent 56.6% of the total cartilaginous fish diversity in the GC. Based on the analysis of biogeographic affinities, most species include their ranges of distribution into the “Sinus-Californian” (55.7%), Mexican (41.5%), and Panamic (36.8%) provinces; 29 species are circumtropical, 7 amphipacific, 5 amphiamerican, and 4 endemic. Based on the IUCN Red List, 1 species is “Critically Endangered,” 2 are “Endangered,” 14 are “Vulnerable,” 23 are “Near Threatened,” 26 are of “Least Concern,” 3 “Not Evaluated,” and 36 are “Data Deficient.” Mexican laws fully protect 9 species classified as “Threatened,” at “Risk of Extinction,” or under “Special Protection,” whereas the rest are protected from fishing at least during 3 months of the year. Thirty-seven species (35%) are of commercial value; another 30 (28%) rare species of low commercial importance have been reported in the catches of artisanal and semi-industrial fisheries during the last 2 decades. Sørensen's coefficient of similarity and cluster analysis between major faunal divisions in the GC suggest the existence of 2 large chondrichthyan assemblages for this region ([NGC-CGC] + [SGC]). This study increases to 106 the species richness of Chondrichthyes known in the GC and serves as the baseline for formulating and implementing of conservation programs for this group of cartilaginous fish.