Surveyors navigate through a remnant dam during the 2024 Atlantic salmon redd count survey on the Sheepscot River. Courtesy of Melissa Cote

Promising signs in local streambeds signal hope for an Atlantic salmon rebound. With continued restoration efforts, that is.

A recent survey of redds (nests) conducted by the Department of Marine Resources and the Maine Coast Heritage Trust revealed a higher-than-expected count in the Sheepscot River, which starts between Georgetown and Southport, winding its way 66 miles north to Montville. 

Redds are created when spawning salmon whip their tails back and forth to dig holes in the gravel in which they deposit their eggs. When the species hatch in the spring, they mature for two or three years before swimming to sea. Some return, but most band with others to trek across the Atlantic toward Greenland. 

For the past two decades, counting redds has largely revealed grim news. By 2000, the population had dropped so significantly that the species was declared federally endangered. Since then, despite millions spent on conservation efforts, runs have only gradually improved. 

The data collected last fall indicated over a dozen redds in the Sheepscot. This came despite unusually low water levels last season. While this is a welcome surprise for many, the long-term picture for Atlantic salmon is still cloudy and could depend on several factors. 

“It’s such a thrill when you come across an Atlantic salmon redd in the Sheepscot because it’s evidence of adults returning to the river,” said Melissa Cote, Midcoast Conservancy Sheepscot River Watershed manager. “I still encounter people that don’t think there are salmon in the Sheepscot, but I let them know they’re here and we’re working to help recover the population.” 

Sheepscot salmon: ‘potentially the most resilient in Maine’

Annual redd surveys estimate the number of adult salmon that return to the Sheepscot River to spawn. In 2022, five redds were recorded; in 2023, there were eight; and this year, there are 13.

It’s important to note that the number of redds does not directly equate to the number of adult salmon. For example, the five redds found in 2022 equated to nine adult salmon that returned that year. 

Jenn Noll, a Maine Department of Marine Resources marine scientist, measures an Atlantic salmon redd found in the Sheepscot River. Courtesy of Melissa Cote

Understanding the decline of the species means acknowledging the watershed at large. 

The Sheepscot River ecosystem is ecologically significant as one of the last remaining rivers — one of eight nationwide — with remnant populations of Atlantic salmon. From its headwaters to the mouth, it supports a community of aquatic and terrestrial species, including river herring, short-nose sturgeon, wood turtles, brook floater mussels, wild eastern brook trout and the rapidly declining saltmarsh sharp-tailed sparrow. 

Since European settlement in the early 20th century, the river has seen many changes, from intensive timber harvests; dam and road construction; modification due to logs; and, most recently, exurban development, which has intensified stormwater pollution. 

Several hypotheses exist for the species’ decline, including water temperature increases, channel changes caused by sedimentation and disturbed riparian conditions. Cote said there is not necessarily one reason, but many. 

In 1997, Ed Baum used historical records to illustrate the magnitude of the loss, estimating there used to be a run of 100,000 adults annually in the nearby Penobscot River. 

This year’s redd count was “surprising” because Sheepscot salmon returned to reproduce despite drought conditions and beaver dams. 

“The Sheepscot River is the most urban of all the statewide watersheds with a genetically distinct population and the most southern,” Cote said. “Because of this, the Sheepscot salmon population is potentially the most resilient in Maine when it comes to climate change.”

Critical protection efforts

Salmon hold significant cultural and economic value. They serve as a food source for various predators, including birds of prey. While creating their redds, salmon also move gravel, releasing essential nutrients into the environment.

The ability to spawn multiple times distinguishes Atlantic salmon from their Pacific counterparts.

To assist with species’ recovery, biologists analyze migration routes and conservationists safeguard shorelines while advocating for stricter regulations on salmon farms.

The Midcoast Conservancy, for example, works with the DMR and Maine Coast Heritage Trust to protect critical spawning habitats in the Sheepscot River and improve the health of the surrounding land.

This is done through targeted outreach and riverfront land acquisitions. Two years ago, the nonprofit acquired a 12.5-acre parcel along the West Branch Sheepscot River near China, a priority area for Atlantic salmon and wild brook trout, and secured it in conservation in perpetuity. 

Advocacy is furthered through monitoring efforts. Cote has partnered with the DMR and the U.S. Fish and Wildlife Service to conduct a rapid stream assessment to understand the on-the-ground habitat conditions that affect watershed processes. Once this is complete, she hopes to develop a restoration plan that benefits several native species, from salmon to brook floater mussels.

Cote emphasized that salmon populations fluctuate annually. 

“While this year’s redd counts are within ranges we’ve seen in the past, they are higher than we expected given the low water levels in the river this past summer and fall,” Cote said. “These findings are encouraging and highlight the resilience of this population but also demonstrate the continued need for restoration in the Sheepscot River if we’re ever to reach population recovery numbers.” 

Later this week, the DMR will plant salmon eggs along the Sheepscot River. This summer, they will assess habitat and juveniles, then collect data for the 2025 redd count in November, once water temperatures drop to 10 degrees Celsius and spawning resumes.