The water in the Penobscot River has been about 80 degrees Fahrenheit for the past few weeks — a level that’s less than optimal for Atlantic salmon — but the run of migrating fish is still the best in nine years, with 1,369 salmon being counted as of Monday, July 13.
Over the past two weeks, despite those warm water temperatures, 329 salmon have been counted according to Jason Valliere, a marine resource scientist for the Maine Department of Marine Resources’ Division of Sea Run Fisheries and Habitat. That’s an average of 15.6 fish per day.
Valliere said the water was 79 degrees on Monday. In order to avoid stressing the salmon, workers at the sorting facility at the Milford Dam don’t handle fish when the water is so warm.
Instead, the fishway gates at the Milford Dam are opened for passage, and the fish are counted when they’re seen on video.
The last time this many salmon have been counted as of mid-July was in 2011, when 2,915 fish had arrived at the Veazie Dam by July 13. That year’s total salmon run was 3,125.
Atlantic salmon in all of Maine’s rivers are listed as endangered, by the federal government and fishing for them is prohibited. The Penobscot is host to the state’s most productive salmon run.
“Temperatures continue to fluctuate such that we are having periods of time where gates are open for free passage [with fish counted on video] and days where it’s cool enough we can close them for broodstock collection,” Vallierere said in a report issued a week ago.
When the water is cooler and fish can be handled safely, some are taken to Craig Brook National Fish Hatchery in Orland, where they’ll serve as broodstock for the next generations of salmon. As of July 13, 204 of the fish had been sent to the hatchery, Valliere said.
And as the summer progresses, Valliere said the dam crew is seeing other fish returning to the sea after spawning.
“We continue to see post-spawn shad dropping downstream headed back to the ocean,” he said. “Juvenile herring, by the thousands, have started showing up too, dropping down through the fishway making their way towards more productive estuarine feeding grounds.”
Workers at the Milford facility don’t just count salmon. All other species that pass through the elevator and sorting tank are also counted. Among the recent visitors was an endangered shortnose sturgeon, a prehistoric fish that Valliere called “a dinosaur.” The sturgeon was fitted with a tracking tag and University of Maine researchers returned it to the river.
The fish counts of some other species, as of July 13: 11,165 American shad, 1.9 million river herring, 5,566 sea lamprey, and 268 striped bass.