Towards mitigating marine-mammal and sea-turtle mortalities in small-scale fisheries

Small-scale fisheries (SSF) are often considered sustainable; but comprise 95% of global fishers and cumulatively evoke substantial ecosystem impacts that include collateral mortalities. Marine mammals and sea turtles are particularly vulnerable to SSF and have been the focus of conservation strategies. However, many strategies have fallen short of objectives. This study aimed to elucidate and help resolve associated issues by: compiling global efforts to mitigate marine-mammal and sea-turtle bycatches/mortalities among SSF; identifying successful outcomes and influencing factors; and then suggesting steps for mitigating remaining problems. Among 150 articles, there was exponential temporal output, with gillnets the most studied gear (67%). Approximately 71% of all publications proposed mitigation measures but of these, efficacy was assessed in fewer than 2/3. While essential for conservation, community engagement was poorly initiated—although relevant studies have increased in the last decade, which may be correlated with studies describing management approaches instead of typical bycatch assessments. Mitigation measures were assessed in a ‘strength-weaknesses-opportunities-and-threats’ analysis. Mitigation measures should benefit multiple species (‘strengths’), avoid high costs/maintenance (‘weaknesses’), be supported by community engagement and governmental aid/enforcement (‘opportunities’), and consider non-compliance (‘threats’). Collateral mortalities can be reduced among SSF, but regional adoption of technology requires impetus that is best achieved via community engagement.