Using software Vortex as a tool towards conservation actions for sharks

Abstract

Elasmobranchs, especially sharks, are part of the most threatened group of animals in the world. Among the factors that negatively affect these populations, the environmental degradation and disordered fishing can be highlighted. Although these threats are well known, the responses of most species to these factors are not fully understood, which makes it difficult to predict potential population responses according to conservation actions. The present study aims to develop a theoretical model based on a real population of white sharks (Carcharodon carcharias) that inhabit Gulf of Mexico, using their biological patterns to identify trends for the populations using Vortex (version 10.0.0.3) as a tool. The construction of the model was based on bibliographic data, considering parameters of life history, demographic rates and main known threats. Data were entered into Vortex software, and two population sizes were tested in the population viability analysis, indicating in both cases that the species tends to lose its genetic diversity over 500 years with a 12% and 51% of probability of extinction, respectively, considering exclusively its biological potential. This results can reflect on an mislead assumption of the real subpopulations size, which shows that the species is inserted into the vortex of extinction even with the existence of protective measures regarding white sharks on the location of the study, and it must incorporate neonates and juveniles individuals on the analysis to generate a consistent result. Despite this, the study suggests that the utilization of Vortex is capable of generating responses necessary for the conservation of sharks by analyzing stochastic events and life history in a simple way.