Atlantic salmon, federally protected under the Endangered Species Act, are returning to the Penobscot River in larger numbers than usual this spring.
As of May 27, a total of 169 Atlantic salmon had been counted at Milford.
“We have only had two years [when] salmon numbers were higher in the month of May since 1978,” said Jason Valliere, a marine resource scientist for the Maine Department of Marine Resources Division of Sea Run Fisheries and Habitat.
The most productive years during that time period came in 2010, when 250 salmon returned to the river, and in 2012, when 200 fish were counted.
More than 40 Atlantic salmon came through the fishway on May 22 alone.
What nobody is able to predict is, what effect such a return might eventually have, if any, on the long-term survivability and viability of the resource. Federal officials predicted in 2019 that it would take 75 years for Gulf of Maine Atlantic salmon to be delisted entirely.
“Fish are still showing up at the Milford fishway in good numbers,” Valliere said of efforts underway at Brookfield Renewable’s hydroelectric dam to guide Atlantic salmon through the dam and back into the river above the project.
The development comes on the heels of what was a disappointing Atlantic salmon run last year. Only 503 fish were counted, making it the lowest return in five years.
Sean Ledwin, the Sea Run Fisheries and Habitat Director for the Department of Marine Resources, previously attributed those numbers to a variety of factors that affect Atlantic salmon.
“The reasons for the low runs are likely low survival of fish at sea, the impacts of drought during their time in the river, and impacts of impoundments and direct mortality at hydropower projects as the fish migrate from the rivers to the sea,” Ledwin said.
The 2021 numbers lagged even though 1,439 Atlantic salmon — the most since 2011 — were counted in 2020.
Maine is home to the only remaining populations of wild Atlantic salmon in the United States. The Penobscot features the state’s most productive salmon run, but fishing for them is prohibited.
On the Kennebec River, where sea-run fish are stymied by four separate hydroelectric projects, 18 Atlantic salmon had been counted at the Lockwood Dam and Benton dams as of May 30.
That’s ahead of last year’s pace, when only 23 salmon were counted there. Those fish are placed in a DMR truck and transported to the Sandy River, a traditional spawning area, where they are released.
There also have been two salmon counted this spring at Benton Falls, located on the Sebasticook River, a tributary of the Kennebec. Last year’s tally was zero.
Back on the Penobscot, there is promising evidence that this could be a strong year for species other than Atlantic salmon.
“We are way ahead of previous years’ numbers from Milford on salmon, shad, sea lamprey and river herring,” Valliere said.
River herring, commonly referred to as alewives, continue their emphatic return to the Penobscot after years of conservation efforts. That included the removal of two dams as part of the Penobscot River Restoration Project.
The estimated total of 1.88 million alewives that had made it through Milford as of last week is 600,000 more than at the same date a year ago and nearly 450,000 higher than the previous high tally of 1,435,952, which came in 2018.
Sea lampreys have numbered 5,066 through the most recent count, while American shad checked in at 1,836.