Targeted environmental monitoring for the effects of medicines used to treat sea-lice infestation on farmed fish

Farmed Atlantic salmon often suffer from sea-lice infestations, which are commonly controlled by the use of a variety of medicines, and the fate of these medicines has implications for the health of the marine environment around fish farms. The Scottish Environment Protection Agency (SEPA) is responsible for monitoring and protecting the quality of Scottish coastal waters and for regulating discharges which may affect water quality, including releases of medicines from fish Farms. We review the utility of established biological effects measurements (biomarkers and bioassays) for monitoring the effects of these medicines. The specificity and suitability of biological effects techniques to the mode of toxic action, metabolism, and environmental fate of the medicines are considered. It is concluded that scope-for-growth measurements in wild and deployed mussels (Mytilus edulis) and lugworm (Arenicola marina) bioassays, in combination with a suite of biomarker techniques, offer the best possibilities.