The grant will pay for successive annual infusions of 5,000 Atlantic salmon — half of them female — into the river until 2022, said Sean Ledwin, director of sea-run fisheries at the Maine Department of Marine Resources.
While only a tiny fraction of the 56 million eggs are expected to survive long enough to contribute to restoring Maine’s wild salmon population, the program could still lead to a 20-fold increase in the number of eggs that Atlantic salmon leave in the river. Atlantic salmon have been listed as endangered under the
federal Endangered Species Act since 2000 and can be legally harvested in the U.S. only from fish farms.
With previous efforts placing as many as 500 fish in the river annually, the 15,000 fish represent the largest infusion of Atlantic salmon into the river in modern history. The program grows out of
a $63.5 million effort that began 15 years ago when a power company agreed to demolish two Penobscot River dams and create a fish bypass in a third, opening nearly 1,000 miles of habitat that had been closed to river-run fish since the 1800s.
Watch: Salmon restoration efforts in Piscataquis River
“The scale and the timing of the project to utilize the high-quality habitats we now have in the river gives us our best opportunity yet to try to realize salmon recovery in the Penobscot River,” Ledwin said. “The large numbers of fish and high-quality habitat should yield the largest numbers of naturally reared offspring that have been seen in the river in decades.”
If successful, and reproducible in other Maine rivers, the program could, with other recovery efforts, significantly aid in efforts to get the Atlantic’s salmon’s endangered species status downgraded in Maine to threatened, meaning that the fish’s extinction would no longer be considered imminent, Ledwin said.
Once a thriving industry, Maine’s commercial wild salmon fishery ended in the 1940s. Today, only
farm-raised Atlantic salmon are found in U.S. supermarkets. The Atlantic salmon’s endangered status has led the U.S., the world’s largest market for the fish, to import 98 percent of its supply, and more recently prompted companies to seek permits to construct land-based salmon farms in Bucksport and Belfast.
Like most of the Atlantic salmon generated for other river-seeding programs, most of the first 5,000 salmon — about 4,500 — that go into the river in fall 2020 will have been grown to smolt size at the U.S. Fish and Wildlife Service hatcheries on Green Lake in Ellsworth and Craig Brook in East Orland.
The rest will come from smolts — fish that are 1 to 2 years old — gathered from the Penobscot River. These fish will be collected in the spring and placed in pens off the coast of the Washington County town of Cutler.
In each of the following years, a growing number of fish stocked in the marine net pens will come from wild origin smolts rather than from Green Lake and Craig Brook, said Jeff Nichols, spokesman for the Maine Department of Marine Resources.
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Program leaders hope that by 2022, the vast majority will have originally come from the Penobscot, Nichols said.
“What you are missing there [with hatchery-grown fish] is all the natural selection from a fish having to survive in the wild and adapt to the environment in the Penobscot River. Those fish have various levels of exposure to natural selection, but they are coddled in the fish hatchery,” Ledwin said.
Atlantic salmon are anadromous, typically spending two or years in freshwater after hatching there, migrating to the ocean for another two or three years, and returning to their natal river to spawn.
Credit: Joshua Royte | The Nature Conservancy
The fish grown in penstocks for two or three years after having been naturally reared in the river should benefit from that exposure and are expected to come back to the river “at a significantly higher rate” than past restoration efforts have produced, Ledwin said.
No one should expect the wild salmon population in the Penobscot and its tributaries to explode in the next three years, said Andrew Lively, a spokesman for
Cooke Aquaculture USA, which raises salmon in farming pens off the Maine coast and is aiding in the restoration effort.
“It has to work gradually. The river has to be able to handle the fish,” Lively said, “but it will certainly be something that will enhance the number of Atlantic salmon in the river.”
The 56 million eggs expected from the 15,000 salmon represent a maximum estimate, given that a single female salmon can create as many as
7,500 eggs. Even if only a fraction of that number survive, they and the 15,000 fish should be enough to fill habitats created by the Penobscot River Restoration Trust’s $63.5 million demolition of the Great Works Dam in 2011 and the Veazie Dam in 2013, as well as the opening of the Howland fish bypass in 2016.
In addition to Cooke Aquaculture and Maine’s Department of Marine Resources, the other partners in the effort are the U.S. Fish and Wildlife Service, the National Marine Fisheries Service and the Penobscot Indian Nation.
As the state’s sole commercial grower of sea-penned Atlantic salmon, Cooke’s involvement will vastly improve state revitalization efforts, said Dwayne Shaw, executive director of the
Downeast Salmon Federation.
The company will help with building the coastal pens, along with feeding and providing the fish with veterinary care. It will also transport the fish to the Penobscot River when they’re ready, Ledwin said. Those offshore pens will vastly expand the number of fish the state can grow for the restoration efforts, he said.
“The two federal hatcheries and our own pair of private hatcheries cannot produce a sufficient quantity of quality salmon for stocking,” Shaw said. “Stocking ‘wild-exposed’ adult salmon is another proven strategy.”
Watch: Why so many fish farms are slated to open in Maine