Supermarket giant Hannaford is facing accusations it displays signs falsely claiming it sells only sustainable seafood.

A new lawsuit claims Hannaford actually sells industrially farmed salmon that gravely harms marine ecosystems and destroys marine life worldwide.

The suit contends Hannaford misleadingly advertises sustainable seafood and sells high-quality, traceable seafood.

The class action lawsuit was filed in federal court in New York.

Hannaford’s parent company. Ahold Delhaize, is the largest grocery retailer on the East Coast. Hannaford has a dominant supermarket presence in Maine.

The lawsuit says Hannaford has reason to know their farmed salmon suppliers produce nutrient pollution that can create oxygen-free dead zones in the ocean; use chemical substances, drugs, and pesticides that can flow into the water surrounding marine cages and have harmful effects on aquatic species; and manage net pens in such a way that farms experience mass salmon mortality events.

The complaint says Hannaford’s suppliers engage in practices that “no reasonable consumer” would consider sustainable.

The 76-page document contains a number of photos of signs at Hannaford locations that advertise sustainable seafood.