The state Department of Environmental Conservation says a tug and a barge that ran aground on the south side of uninhabited Ukolnoi Island left a thin sheen of diesel fuel.
Response crews have deployed contain boom around the tug to help minimize any environmental impact after an aerial survey Friday found a broken, rainbow sheen around the grounded vessels.
The tugboat, Polar Wind, and barge, Unimak Trader, ran aground Tuesday within the designated critical habitat for Stellar sea lions and the southwest sea otters. The agency says there have been no reports of harmed wildlife.
The amount of fuel on board the Polar Wind has been updated to more than 20,500 gallons. The barge, meanwhile, has 1.5 million pounds of frozen seafood.