TRAVERSE CITY (AP) — Federal regulators said Wednesday they will consider extending legal protections to lake sturgeon — prehistoric fish once abundant in the Great Lakes but reduced to dangerously low numbers by overfishing, pollution and habitat destruction.

The U.S. Fish and Wildlife Service said an initial review had yielded “substantial information” on continuing threats to the sturgeon, justifying a more detailed study of whether they should be listed under the Endangered Species Act.

Designating the sturgeon as endangered or threatened could boost efforts to open more spawning areas, said Jessica Collier, a fish biologist with the service based in Green Bay, Wisconsin.

“Sturgeon live out in the lakes and migrate into rivers to reproduce,” Collier said. “One of the biggest impediments to their recovery right now is that they don’t have access to river habitat, usually because of blockades like dams.”

More than 500 other species are waiting for similar investigations, meaning it could take years for the agency to reach a decision on the sturgeon.

Still, the advocacy group that petitioned the Fish and Wildlife Service to conduct the review said the initial finding was a positive step.

“It’s a big deal,” said Jeff Miller, senior conservation advocate with the Center for Biological Diversity. “There are a lot of fishing groups, tribes and states doing amazing work to bring these fish back. But imperiled species have a much better chance of recovery if they’re on the federal list than if they aren’t.”

The range of lake sturgeons extends from Hudson Bay through the Great Lakes to the lower Mississippi River and includes portions of 18 states. They can exceed 8 feet in length and weigh up to 300 pounds.

Covered with thick bony plates instead of scales, they feed on bottom-dwelling organisms such as crustaceans and insect larvae. Because they live as long as a century and take 15 to 25 years to reach spawning age, they have a low reproductive rate.