Cost‐effective mitigation strategies to reduce bycatch threats to cetaceans identified using return‐on‐investment analysis

Solutions to mitigate cetacean bycatch have targeted specific fisheries and gears, however, these targeted mechanisms can be effective if interactions occur only between a particular population and gear type or fishery. Most dolphin and whale populations face incidental capture from multiple fisheries and gears. Accordingly, broad-scale spatial approaches to mitigation are needed to address bycatch across multiple species at the scale at which the species occur. This study applied decision-theoretic bio-economic techniques to inform the reduction of cetacean bycatch in a case study of Australian fisheries. Spatial mapping highlighted substantial variation in the location of optimal cost-effective management strategies. Although trawl-net modifications were the cheapest strategy overall, there were many locations where spatial closures were the  most cost-effective solution (despite their high costs to fisheries) due to their effectiveness in reducing all fisheries interactions.