Effect of government removal of salmon farms on sea lice infection of juvenile wild salmon in the Discovery Islands

Abstract

In response to a federal government order, the number of salmon farms operating in the Discovery Islands region declined from eight in 2020, to one in 2022. Over this period, 1627 juvenile pink ( Oncorhynchus gorbuscha) and chum ( Oncorhynchus keta) salmon captured at sites throughout the study area were examined for sea lice. The average number of sea lice per juvenile salmon declined by 96% over the study period. Such a substantial decline was not witnessed in similar samples from the nearby Broughton Archipelago. The decline could not be attributed to chance sampling, and only a small proportion of it was associated with environmental fluctuations.