Determining potential management strategies for the elasmobranchs bycatch of the Mexican shrimp trawl fishery of the Gulf of Mexico through a vulnerability analysis

Shrimp trawl fisheries capture several species of elasmobranchs as bycatch that are commonly unreported, this lack of data makes it difficult to assess their populations using quantitative stock assessment methods. Rapid evaluations like the productivity and susceptibility analysis (PSA), can help to determine species at risk of overexploitation and prioritize research, management and conservation efforts. The relative vulnerability (V) of 16 elasmobranch species associated to the Mexican shrimp trawl fishery in the Gulf of Mexico was determined using a PSA. The information of bycatch elasmobranch was collected by observer's onboard shrimp fishing vessels in 55 fishing trips during the 2013-2017 period. Two hypothetical scenarios to test potential management strategies were developed to observe changes in V based on the current fishing practices. We determined that most elasmobranch species (n= 14) had low V (<1.8) related to this fishery, mostly as a result of the high productivity (P) of the coastal-demersal species and the low susceptibility (S) of the coastalsemioceanic ones. Only two species had a moderate V, Pseudobatos lentiginosus (1.87) and Squatina dumeril (1.85). The vulnerability of these two species could decrease through ensuring post-capture release practices and the protection of their aggregation, since both actions would lower their S and V. Post-capture release might be the most feasible potential strategy for both species, whereas protection of species aggregations would require further investigation to support its effect in the mitigation of mortality from bycatch. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

The shrimp trawl fishery in the Gulf of Mexico captures several elasmobranch species as bycatch, with rapid evaluations like PSA helping to determine species at risk of overexploitation. Most elasmobranch species associated with this fishery have low vulnerability, with only two species showing moderate vulnerability. Measures such as post-capture release practices and protection of species aggregations could help reduce the vulnerability of these species.