Could Maine’s new ISA rules change how salmon farms respond to outbreaks?

Cooke’s Dark Harbour site in Maine. Photo: Cooke Aquaculture

Maine is proposing changes to its infectious salmon anaemia rules that would end the automatic presumption that farms should be depopulated following detection of pathogenic ISA virus.

The proposed rules follow the expiry in April of the US Department of Agriculture’s voluntary ISA control programme, which had provided the framework for managing the disease in Maine’s Atlantic salmon sector.

Under the new state regime, detection of HPR-deleted ISAV would not by itself trigger an order to cull a farm. Maine would retain the authority to require depopulation where fish show clinical disease and the operator has failed to take appropriate action.

The state said both HPR0 and HPR-deleted strains of the virus are considered endemic in Maine.

The changes were proposed on Wednesday as Maine moves to replace the federal programme with its own disease-control framework.