Sustained fishing threatens globally protected species: Insights from digital catch and genomic data

Small-scale fisheries capture a wide marine biodiversity including highly vulnerable and endangered species. Despite global conservation efforts, at regional scale, strategies to conserve threatened species are often constrained by poor biological information and a paucity of fisheries data to understand the level of threat posed to their populations. In Myanmar, devil and manta rays (mobulids) are caught for meat consumption and export of gill plates. The impact of this exploitation is not fully understood as mobulid rays, especially in this region, have been poorly studied, catch levels are under-reported and the fishery is unregulated. An accurate knowledge of the species composition and catch levels is an important first step to inform potential management and protection strategies for these species. This study is the first to combine digital catch recording alongside genomic tools to analyze mobulid rays caught in the Tanintharyi Region of south Myanmar. Our catch data analyses indicate a sustained catch and decrease in total landings of mobulids from 2016 to 2018 in Tanintharyi. We identified five species of mobulid rays, including the first record of M. tarapacana for Myanmar. Our analyses of population genomics provided evidence of structured populations of M. thurstoni and partial admixture in M. mobular. Our findings are highly valuable 1) contributing to fill the knowledge gap for these threaten species in the region, and 2) as the first documentation of sustained fishing pressure these rays are exposed to, and the species under potential fishing threat in the Tanintharyi Region, a high priority biodiversity hotspot. • Sustained fishing pressure on mobulid rays in a high priority biodiversity hotspot. • Catch data indicated a decrease in total landed catch of mobulid rays. • Report catches for devil rays biased toward sexually immature individuals. • Four species of devil ray and one of manta ray were identified with DNA barcoding. • First population genomic study of devil rays using genome-wide genotyping. • Evidence of structured populations found for the bent-fin devil ray, M. thurstoni .