Salish Sea Ecosystem Conference

Toxicity testing of Atlantic salmon aquaculture chemotherapeutants on spot prawns and benthic invertebrates

Demand for protein sources is high in North America and growing throughout the world. Global declines in fisheries has encouraged coastal regions to embrace aquaculture as a means of reconciling the growing pressures on wild fish stocks with this demand. Intensive salmon farming practices result in periodic infestations with naturally-occurring parasitic copepods referred to as “sea lice”. To prevent productivity losses, a variety of chemical and physical treatments have been implemented through regulatory systems or emergency applications. One objective of this study is to determine if these chemo-therapeutic treatments pose a risk to other non-target marine organisms including crustaceans such as the Spot prawn (Pandalus platyceros). These organisms can be both culturally and economically important to local First Nations and all residents of the Salish Sea region, as well as crucial components of marine ecosystems. The sub-chronic toxicity of the sea lice pesticides Slice® (active ingredient: emamectin benzoate) was assessed for lethal and sub-lethal effects on Pacific prawns, amphipods, and polychaetes which are all found in areas where aquaculture pens exist. Slice and ivermectin whole sediment exposures were conducted. Test concentrations were representative of environmentally-relevant levels. The toxicity of these treatments was assessed using the endpoints of: mortality, growth, and behavioural response. Preliminary results indicate a concentration-response relationship for various selected endpoints.