Maine salmon farms face scrutiny over fish health and environmental risks

USA – Salmon farming in Maine is facing renewed scrutiny over fish health, disease risks and environmental impacts, with conservation groups and local fishing communities urging regulators to reconsider the renewal of nine aquaculture leases operated by Cooke Aquaculture.

Cooke, Maine’s only commercial salmon producer, holds 23 active aquaculture leases in the state, with nine currently up for renewal.

Critics argue that open-net salmon farms could threaten wild Atlantic salmon through escaped farmed fish, disease transmission and pollution from fish waste and excess feed.

Dwayne Shaw, executive director of the Downeast Salmon Federation, said escaped farmed salmon could undermine efforts to restore Maine’s critically low wild Atlantic salmon population.

“Farmed salmon that enter rivers could breed with wild fish,” Shaw said, warning that escapes could affect the long-term viability of wild populations and potentially spread diseases and parasites.

Cooke has recorded previous escapes, including more than 50,000 salmon from two sites near Cross Island in 2023 after cage damage that the company attributed to a seal attack.

Disease and waste concerns

Conservation Law Foundation filed a complaint against Cooke in 2025 alleging environmental violations at 13 salmon farming sites. 

The organisation raised concerns over sulfide pollution from decomposing fish waste, nutrient pollution, pathogens and sea lice.

Heather Govern, the foundation’s vice president for clean air and water, said sulfide pollution beneath and around net pens could harm marine life.

Cooke has rejected the allegations, saying they are “false, misleading and lack any substantiating evidence.” 

The company has also said its farms comply with state requirements and are subject to regulatory inspections and monitoring.

The Maine Department of Marine Resources says salmon farming is not considered a major threat to the recovery of wild Atlantic salmon. 

The agency also conducts genetic screening of salmon collected for broodstock to identify fish originating from aquaculture operations.

The debate comes as Maine’s aquaculture industry faces pressure to balance production with protection of marine ecosystems and wild fisheries.

Cooke employs about 230 people in the state and argues that salmon farming remains an important part of the working waterfront in coastal communities.

Meanwhile, environmental and fishing groups are calling for stronger independent monitoring, tighter controls and science-based management of coastal waters before further expansion of industrial-scale aquaculture.

The dispute highlights the growing importance of fish health, biosecurity, environmental management and responsible aquaculture practices as salmon farming expands globally.

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