Use of the productivity and susceptibility analysis and a rapid management-risk assessment to evaluate the vulnerability of sharks caught off the west coast of Baja California Sur, Mexico

Quantitative assessments of shark populations are difficult to undertake due to the scarcity of studies focusing on species identification and landings. We used the productivity and susceptibility analysis and a rapid management-risk assessment (M-risk) method to examine the impact of the artisanal fishery on 29 shark species captured and landed off the west coast of Baja California Sur. We also examined the regulatory measures currently applied to shark fisheries in Mexico to assess their efficacy in mitigating the impact on fishing mortality. Twenty-eight species had low productivity; only Mustelus californicus was placed in the moderate productivity category. Seventeen species had high susceptibility while 12 were placed in the moderate category. Twenty species were placed in the high vulnerability category, and nine in the moderate category. The five most vulnerable species were Sphyrna zygaena, Squatina californica, Heterodontus francisci, Isurus oxyrinchus, and Carcharhinus falciformis. The management-risk is high for all species; artisanal fisheries have a significant impact particularly on coastal shark species, which can be very sensitive to overfishing as well as large species that use the coastal area during the early stages of their development. Research priorities should include studies assessing the elasticity and demographic aspects of S. zygaena and I. oxyrinchus. Squatina californica and T. semifasciata require urgent attention due to the risk of extirpation. New regulations and improvements to existing legislation in Mexico may have a positive impact in shark populations, which can be examined in future assessments.