ELLSWORTH — The Department of Marine Resources will employ a novel approach to rearing Atlantic salmon for restoring native populations on the East Branch of the Penobscot River.
The project, funded through a $1,075,000 National Oceanic and Atmospheric Administration Species Recovery Grant, will involve a partnership among DMR, Cooke Aquaculture USA, the U.S. Fish and Wildlife Service, NOAA Fisheries and the Penobscot Indian Nation to grow juvenile Atlantic salmon to adult size in aquaculture pens located in Machias Bay near Cutler. The adult salmon will then be released into the East Branch of the Penobscot, a river with large amounts of high-quality salmon habitat, to spawn.
Smolts raised from native broodstock by the U.S. Fish and Wildlife Service at the Green Lake National Fish Hatchery in Ellsworth and smolts captured in the wild using rotary screw traps will be used to stock the marine net pens in 2020, 2021 and 2022. To ensure the genetic integrity of salmon in the river, only smolts of Penobscot River origin will be released.
Approximately 5,000 adult fish will be transported from the net pens to target tributaries and the mainstem of the East Branch of the Penobscot River in the fall of 2021 or 2022, where they will find suitable habitat to naturally spawn. This will result in more spawning adults than have been present in the Penobscot River for decades.
Plans call for increasing the number of smolts captured in the wild from the East Branch to be used to supply juveniles that will be grown out in the net pens. While hatchery spawned fish help ensure an adequate supply of fish for recovery goals, salmon spawned in the natural environment are more robust, a consequence of natural selection which results in fish that are better suited to survival in the wild.
The smolts will be placed in net pens under a limited-purpose aquaculture lease off Cutler, where they will be fed and managed in cooperation with Cooke Aquaculture USA for 16 to 30 months while they grow to mature adults. DMR will hold the lease while Cooke will supply the pens and feed for the salmon as they grow.
“We are committed to be part of this wild Atlantic salmon enhancement project in Maine,” Glenn Cooke, CEO of Cooke Aquaculture USA said in a statement announcing the project. “Cooke Aquaculture has the experience working with Atlantic salmon in their natural environment based on proven aquaculture and fish-health science. Working with the Penobscot Nation and government partners, together we will make this restoration program a success by seeing the fish return to their native waters.”
While cultivating Atlantic salmon in net pens is not new in Maine, using them to cultivate salmon for conservation purposes at this scale is. Similar efforts are already showing promise in a Bay of Fundy partnership between Cooke and Canadian provincial and federal governments, First Nations and academia.
As populations expand, the goal is to build healthy wild populations of Atlantic salmon on the East Branch, including the potential for removing the fish from its federal listing as an endangered species.
“The estimated 5,000 adults produced by this effort could result in 20 times more eggs in the gravel in the Penobscot River basin compared to existing stocking and natural reproduction,” said Sean Ledwin, director of DMR’s Searun Fisheries and Habitat Division.
The program will involve surveys of redds in spawning areas to assess spawning success of released fish. Released fish will also be tracked using Passive integrated transponders (PIT tags) and radio telemetry. Electrofishing surveys and use of rotary screw traps, along with genetic analysis, will be used to assess the abundance of offspring from this effort.
The program will also include a public outreach effort undertaken by the department and other program partners that will provide information on salmon and other sea-run species, and the impact of protecting ecosystems on which they rely.
“The Penobscot Indian Nation has inhabited the Penobscot River drainage since time immemorial.” Dan McCaw, fisheries program manager for the Penobscot Nation, said in a statement. “The deep cultural, spiritual and historical connections between the tribe and the Atlantic salmon of the Penobscot River go back thousands of years. The Penobscot Nation is hopeful that this new program can help to restore this iconic species to its ancestral homeland and applauds the collaborative nature of this multi-stakeholder endeavor.”