PORTLAND – At least five dead minke whales have been found floating off the Maine coast in the past 16 days.

The strange occurrence is being investigated by state and federal officials. Some of the whales had marks or wounds that appeared to be caused by fishing gear, and one had an unusual square wound in its abdomen.

The deaths are fueling accusations within the commercial fishing industry. But officials say it’s too early to tell what killed the whales and what kind of fishing gear might have caused the marks.

“It’s an unprecedented number of minke carcasses in such a short time,” said George Liles, spokesman for the National Marine Fisheries Service. “There’s a lot of talk and a lot of speculation. We just really don’t know what [the cause is].”

Minke whales are among the most common whales in the Gulf of Maine. They are not an endangered species but are legally protected by the U.S. Marine Mammal Protection Act.

Anyone who injures or kills a minke whale could face legal penalties, and fishing practices that harm the whales could face restrictions.

Federal investigators met with officials of the Maine Department of Marine Resources on Monday to discuss the deaths but did not come to any decisions. The federal agency is the lead investigator and is reviewing photos of the whales and other evidence gathered by Maine authorities.

There have been nine reports of floating minke carcasses between Cape Neddick and North Haven since Sept. 13. Some of the sightings are believed to be from different people who saw the same whales. The last report of a dead whale came Sunday from the Cape Neddick area. It appears to be the same whale first reported in that area Sept. 19.

Some of the whales were badly decomposed and of little help to investigators.

On Sept. 13, officials photographed and took tissue samples from a 20-foot-long whale found near Harpswell. It had red marks behind the dorsal fin and on its tail flukes that look like they were caused by a fishing line, Liles said.

The examination may help determine if the whale was injured while alive or if some or all of the marks were made after it was dead.

Another whale found Sept. 17 near North Haven had marks that appeared to be caused by line at the base of its tail flukes.

There was no fishing gear on the whales, and no immediate way to know whether the marks were made by ropes or nets.