NEW ORLEANS (AP) — Weathered oil in the form of tar has washed up on some Louisiana beaches from Gulf waters churned by Hurricane Isaac, prompting restrictions of fishing in some waters and tests to determine whether the source is submerged oil from the 2010 Deepwater Horizon disaster.

“I’d say there’s a smoking gun,” said Garret Graves, Gov. Bobby Jindal’s top adviser on coastal issues. He said tests were being done to verify the source of the oil.