Mitigating and managing the impacts of gelatinous zooplankton on finfish aquaculture

Gelatinous zooplankton, including cnidarian medusae, ctenophores and salps, can kill and injure fish. They impose an enormous economic cost on the global finfish aquaculture industry through stock losses and increased production costs. Although the impacts of gelatinous zooplankton are well established, protocols to mitigate gelatinous zooplankton are not. Appropriate mitigation depends on the type of gelatinous zooplankton (e.g. stinging or non-stinging) and the nature of their impact (e.g. stinging or occlusion of nets). Here we review approaches that are, or could be used, to mitigate gelatinous zooplankton. We focus on methods that (1) minimise interactions between farmed fish and gelatinous zooplankton, (2) respond to gelatinous zooplankton ingress into farms and pens, and (3) forecast potential ingress of gelatinous zooplankton. Research and development into gelatinous zooplankton mitigation seriously lags efforts to manage other biological hazards such as parasites and harmful algal blooms and more targeted approaches to monitoring and mitigating gelatinous zooplankton are needed to minimise economic losses for industry and ensure fish welfare. We suggest the finfish aquaculture industry, ecologists, engineers and biomedical researchers collaborate towards improving monitoring and predictive model development to provide advanced warning and avoidance of gelatinous zooplankton; engineering more effective methods to prevent ingress of gelatinous zooplankton into pens; and developing prophylactic and therapeutic treatments for fish that have been exposed to gelatinous zooplankton.