GARDINER — Around a dozen community members waved signs at passing cars on Bridge Street Friday afternoon and answered questions from passersby.

They’re advocating for fish.

The group is trying to increase the community’s interest in finding a way to allow alewives to swim up Cobbossee Stream to spawn each spring. Alewives, a river herring, swim up rivers and streams each May and June to spawn in lakes and ponds.

The construction of dams and industrial pollution diminished the fishery’s population over the last two centuries, according to the Maine Department of Marine Resources. In the past 30 years, fish passages and stocking efforts significantly increased the amount of spawning habitat available to alewives, according to the department.

There have been recent efforts elsewhere in the state to restore migratory routes for alewives, including to China Lake from the Sebasticook River, where a coalition of conservation groups and government agencies are behind an initiative to bypass or remove six dams on Outlet Stream in Vassalboro. Although the project could cost more than $2 million, supporters say it’s worth it because of the impact the action would have on the water quality in China Lake and the overall population of alewives.

In Gardiner, three dams on Cobbossee Stream block the alewives’ passage upstream.

Tina Wood, a Gardiner resident who led the demonstration Friday, said the group doesn’t yet know what it would try to do to open up the route for alewives. She said the solution could be some type of passage around the dams and not necessarily require removing the dams.

The group was also letting people know that Nate Gray, a Maine Department of Marine Resources biologist specializing in alewives, is scheduled to speak about the issue at a Gardiner City Council meeting June 17. Gray couldn’t be reached for comment.

Runs of alewives have been a boon in central Maine in recent years with the removal of dams, particularly in Benton. There, where millions of alewives swim up the Sebasticook River to reach the Benton Falls Dam, a robust commercial fishery has developed. Crews can normally fill 1,000 crates with about 250,000 pounds of fish during the month-long season.

But this season, fishermen expect to catch less than a third of that bounty because of damage to the Benton Falls hydroelectric dam that has forced alewife harvesting farther downstream, where the fish are more difficult to catch.

In Gardiner, one man who stopped on Bridge Street to talk to Wood on Friday told her he would be concerned if the dams on Cobbossee Stream were taken out because it would lower the water level on Pleasant Pond.

Wood, who became interested in alewives while in the Maine Master Naturalist Program last year, said the group wants to work with the interests of different parties, including economic interests, to find a solution.

“There’s a win-win for everybody,” she said.

Paul Koenig — 621-5663

[email protected]

Twitter: @pdkoenig