Maine Students Try To Help State’s Alewife, Threatened By Dams And Obstructions

By on November 17, 2015

More than 52 percent of the historic alewife spawning habitat in Maine is blocked by dams or other obstructions. But that hasn’t stopped students at the College of the Atlantic from trying to help the anadromous fish.

According to a release from the school, a class led by Chris Petersen, marine ecology professor at the university, has been working to aid the struggling alewife for some time. The efforts began in 2008 when Petersen began partnering with local organizations working to help restore historic alewife runs.

Some of those organizations include Somes-Meynell Wildlife Sanctuary and the Maine Department of Natural Resources.

Through the years, students in Petersen’s classes have achieved a lot of good for the state’s alewives. This is exemplified by projects to build better fishways, remove unneeded dams and repair neglected spawning channels. They’ve also restored stream habitats and taken a stab at monitoring alewife numbers.

Those efforts have been aided by biological sampling and fish counting, as well as water quality testing, which Petersen says is a key for managing alewife returns.

And students have been able to turn those experiences into actual research projects.

One, led by Emily Argo in 2010, looked at the possibility of restoring Denning Brook, a stream in Somesville, Maine, as an alewife run. In it, Argo lays out some of the history of the stream, along with a summary of physical and water quality characteristics that would need to be met in order to maintain a successful alewife run in the waterway.

Alewives gathered in a net. (Credit: Chris Petersen / College of the Atlantic)

Alewives gathered in a net. (Credit: Chris Petersen / College of the Atlantic)

Another project, led by Alex Brett, who graduated from the school in 2011, looked to determine if bird predation went up or down on days when more fish were coming through Somes Brook. His investigation found that the more fish that were swimming through, the less likely it was that they would be eaten by a bird.

Most of Brett’s work involved using nets and other collection devices to count fish, something that Petersen maintains is one of his favorite activities. He loves to count fish and root them on, he says, and is especially fascinated by the relationships between the fish and their predators — eagles, ospreys, cormorants and mergansers.

From his perspective, as well as ecologically, alewives are important. Strengthening their populations benefits the fishermen who collect them, the lobstermen who value them as bait, and watersheds themselves.

Alewives also play an important role in transporting nutrients between marine and freshwater ecosystems. And they provide food for freshwater species like trout, bass, and landlocked salmon, as well as for marine species such as birds, seals, and predatory fish.

According to the Maine DNR, alewife landings peaked in 1956 at around 4.5 million pounds, and in 1975 at just under 4 million pounds. By 1981, their populations had been so diminished by overfishing that only 100,000 pounds were harvested.

Alewife stocks have slowly recovered since that time, largely due to conservation and monitoring efforts around the state. In 2014, Maine alewife landings totaled around 1.6 million pounds.


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