A slick of oil has been spotted in Witless Bay, inside the Witless Bay Ecological Reserve.

The reserve is home to North America's largest colony of Atlantic puffins.

Jeannine Winkel of Molly Bawn Whale and Puffin Tours said she first noticed the rainbow-like streaks on the water just before 2:00 p.m. Friday when the tour boat set out for its first run of the day.

Within just a few hours, she said the slick had grown significantly and was moving toward Mobile Bay, approximately 40 kilometres south of St. John's.

Jeannine Winkel of Molly Bawn Whale and Puffin Tours says the slick the is now half a mile wide and two miles long. (Jeannine Winkel)

By the time she left to go home after 4:30 p.m., the slick had grown to nearly a kilometre wide and over three kilometres long, spreading from outside of Mobile Bay to Great Island.

DFO confirmed in a statement late Friday that an American fishing vessel, the Eyelander, ran aground early that morning near Green Island, four nautical miles southeast of Witless Bay. The five people on board were transported safely to Bay Bulls and the ship was later able to sail into Witless Bay under its own power.

According to DFO, the ship reported a fuel leak, saying that diesel fuel leaking from a bilge pump was released into the ocean. Some of that fuel was recovered, but most was unrecoverable and "dispersed with wave and tidal action."

Jeannine Winkel of Molly Bawn Whale and Puffin Tours first noticed the oil Friday afternoon. (Jeannine Winkel)

"No pollution has been reported in Witless Bay," the statement said.

But Winkel doesn't think the incident will be without consequence.

"There will be birds affected by that oil. Even if you clean them up afterwards, they will still die because they will ingest the oil," said Winkel. "It is right near an area where there were birds sitting on the water. I saw one gannet sitting pretty close to that oil patch. I think it must have gotten some on their body … and there were a lot of puffins in the area."

"It's really sad to hear that's all that will be done."

She noted that Green Island is part of the ecological reserve and boats are supposed to stay 100 meters from the island.

The Canadian Coast Guard is monitoring the situation with assistance from the Canadian Wildlife Service. Transport Canada is also investigating.