Mitigating the effect of by-catch on endangered marine life

Abstract

The fishing gear deployed by fishermen in seas and oceans throughout the world not only captures target species but also unintentionally ensnares non-target species, a phenomenon known as ‘by-catch’. This unintended capture of marine life can represent significant challenges for the fishing industry, with adverse impacts on both the environment and species such as sea turtles, marine mammals, seabirds and elasmobranchs, which may be injured or even killed. To address this problem, the fishing industry has implemented regulations and mitigation measures. In this literature review, we have examined 389 papers published between 2010 and 2022 that assess the effectiveness of these measures. Taking into account the fishing gear with which each group interacts the most, trawls for sea turtles, gillnets for marine mammals and longlines for seabirds and elasmobranchs, it has been demonstrated that ‘TEDs’ (Turtle Excluder Devices) are an effective measure for sea turtles, ‘pingers’ for marine mammals and ‘BSLs’ (Bird Scaring Lines), more commonly known as ‘tori lines’, for seabirds. The most complex case is that of elasmobranchs, and the most effective measure has yet to be discovered. This complexity arises from the ongoing targeted fishing of these species, resulting in less monitoring of their catches and, therefore, fewer surveys. Overall, we encourage the global implementation of these measures by the fishing industry in order to reduce by-catch in an attempt to ensure the future of many endangered species.