Unbounding fish: Assessing vulnerability to overexploitation for transboundary fish populations

Abstract

AbstractTropical fish populations often traverse management boundaries, making it difficult to evaluate species vulnerabilities and optimise sustainable fishing goals. Most vulnerability assessments rely on life histories and gear susceptibility, but ignore transboundary differences in management, which can strongly affect vulnerability. We propose a novel vulnerability matrix, the Biology – Transboundary Management (BTM) index for individual fish populations based on 1) Species specific vulnerability 2) distribution of genetically-distinct populations with respect to jurisdictional boundaries and 3) sustainability of management practices across jurisdictions. Combining single-nucleotide polymorphism (SNP) analyses and policy assessments, we evaluate relative vulnerabilities of nine commercially relevant fish populations over a 3400km stretch of India’s west coast, across multiple jurisdictions. The BTM matrix indicates that transboundary differences in management strongly influences biological vulnerability. The matrix is sensitive to population-level differences and policy changes. Our analyses emphasise the need for population-level assessments and transboundary cooperation in achieving sustainable multi species fisheries.