BOSTON (AP) – Many more endangered right whales may be dying than previously believed, marine scientists said Friday in an appeal for emergency action to prevent human-caused deaths of the animal.

In an article published in the journal Science, the researchers estimated that North Atlantic right whale deaths may be underreported by as much as 83 percent annually.

That could mean as many as 47 whales have died in the last 16 months, instead of the confirmed eight deaths – a toll already considered a blow to a species with an estimated population of about 350.

There isn’t time to wait for proposed protections to slog through the federal rule-making process, said Amy Knowlton, a New England Aquarium researcher and one of the article’s 18 co-authors.

“We can’t wait to deal with a bureaucratic maze,” said Knowlton, whose co-authors included scientists from Woods Hole Oceanographic Institution and various universities.

The Science article, citing the Endangered Species Act, calls for emergency rules to protect against ship strikes and fishing gear entanglements, the two primary human-related causes of right whale deaths.

Proposed rules include slowing down ships in whale-heavy areas and reducing the amount of floating fishing line in the water. Gear and voluntary speed restrictions are already in place, but the new rules would significantly broaden requirements and improve their effectiveness, advocates say.

“We really do have tangible solutions in hand,” Knowlton said.

Federal regulators said emergency rules could be put in place six months earlier than the normal 18- to 24-month process, but they would not be permanent and would not save much time since the final rules are close to completion. And they said rules could do more harm than good without proper review and public input.

“It’s not that doing something dramatic isn’t possible,” said Teri Frady, spokeswoman for the federal NOAA Fisheries Service. “It’s figuring out what it’s going to be and whether it’s going to work.”

Frady said final rules to protect whales from fishing gear entanglements should be in force by the end of the year and the ship strike rules should be in place by spring of 2006.

The proposed rules have been questioned by fishermen, who worry new whale-safe gear requirements would be too expensive, and the shipping industry, which says it would lose money and compromise safety by slowing down or altering routes to avoid the animals.

The North Atlantic right whale was nearly hunted out of existence in the late 18th century and has struggled since. Scientists said the eight known whale deaths in the last 16 months were particularly devastating because four were females just starting to bear calves.

Knowlton said the estimate of unreported whale deaths is based on a population model that considers the known death rates of male, female and juvenile right whales. The projection that 83 percent of whale deaths are undetected is alarming, but fits with recent aerial and ocean surveys of the difficult-to-track population, Knowlton said.

Scientists don’t presume a whale dead until it hasn’t been seen for six years. It may be that whales that haven’t been spotted within the six-year lag are simply gone without being spotted, Knowlton said.

Frady declined to comment on the estimate of unreported whale deaths, except to say, “The thing we all agree on is the condition of the stock is not good.”