Demographic analyses reveal differential biological vulnerability in four Southwestern Atlantic skates

Abstract

More than 33 skate species have been registered in the Southwestern Atlantic Ocean (SAO) 34°S, where hotspots of the endemic threatened marine chondrichthyans with high scientific and conservation priorities have been detected. The lack of species-specific landing data highlights the importance of biological data-based methods to determine the vulnerability and productivity of skate species. In this work, we estimated the demographic parameters for the skates Atlantoraja castelnaui, Rioraja agassizi, Sympterygia bonapartii, and Zearaja brevicaudata in SAO, by implementing Leslie matrix models. The finite rate of population growth ( ʎ) for the four skate's species ranged from 1.036 ( Z. brevicaudata) to 1.196 ( R. agassizi). Elasticity analyses and the performance of different harvest strategies show that reducing juvenile catches appears to be one of the most effective management actions for these species since they result in higher survivorship of age classes with more influence in λ. Differences in the biological productivity of the skates suggest that, to achieve sustainable exploitation of skates, the commitment of all stakeholders to improve species-level information is necessary.