Returning salmon to Maine will take 75 years, $350M

The Atlantic salmon was once plentiful in Maine rivers. (Courtesy photo)

The U.S. Fish and Wildlife Service released a recovery plan for the Gulf of Maine salmon earlier this week.

The fish, long a staple of Maine rivers, has been listed as endangered since 2000.

The plan's cost is around $350 million, and the effort to fully rejuvenate the species could take as long as 75 years, officials say.

The wildlife service says it is estimated about 100,000 adult salmon came back to the Penobscot River each year in the 1800s, but that less than 750 returned to Maine rivers in 2015.

Dams are the top concern for the species' survival, with costly, sometimes ineffective fish ladders making political backing of the plan contentious in local communities.

Other threats include climate change, competition with other species and poor water quality. Commercial fishing off the Greenland coast is also seen as a threat.

The fish and wildlife service and NOAA, which is also involved in the recovery effort, are taking public comments on the plan through the end of next month.

Funding for the recovery program would come from a mix of federal, state and private money.