Alex Brett ’11 checks conditions at the Somes Brook fish ladder.Alex Brett ’11 checks conditions at the Somes Brook fish ladder. Credit: Chris Petersen

Once overflowing in Maine waters, the alewife has taken hits from overfishing, watershed pollution, and river dams blocking fish passage. The anadromous fish has been the subject of statewide restoration efforts, and since 2008 College of the Atlantic marine ecology professor Chris Petersen has been working with a coalition of partners to restore historic local alewife waters.

“In the past twenty years, we’ve made a lot of improvements and [the alewives] are doing much better,” Petersen said. “They’re still not back to the levels of the 1950s or 1970s - that would be our first goal.”

Petersen focused on local efforts to improve the beleaguered alewife population during a recent presentation at the Somes-Meynell Wildlife Sanctuary headquarters.

Working in partnership with Somes-Meynell and Claire Enterline of the Maine Department of Marine Resources, Petersen and his students have labored to build effective fishways, remove unnecessary dams, repair neglected runs, restore and conserve stream habitats, and keep a close eye on populations, Petersen said. Assessing the health of alewife runs is accomplished by biological sampling, counting, water chemical testing, and scale collection.

COA students have aided this process by counting fish, setting up fish ladders, and clearing debris from Somes Brook. Some COA students have also designed projects around the Somesville alewife run.

Alewives are an important part of Maine's coastal river ecology.Alewives are an important part of Maine's coastal river ecology. Credit: Chris PetersenAlex Brett ’11 conducted a study to determine whether or not bird predation increased or decreased on days when more fish were coming through. He discovered that the fish had some safety in numbers– on days when many fish swam through the run, a lower percentage of fish were eaten than on days with a slower trickle of fish. Other students have studied the history of the stream and the mills that have been built alongside it. Last spring, students did chemical testing to determine how the presence of alewives impacted the nutrient levels in the water.

The work is enjoyable on many levels, Petersen said.  

“I love data.  I love just sitting there and counting fish and, you know, rooting them on,” he said. “The most fun thing is having thousands of fish and [many predators] around… There might be bald eagles, and ospreys, and cormorants, and mergansers, and seals, and [with] all the fish streaming through… it’s kind of a spectacle of nature.”

According to the DMR, alewife landings peaked in 1956 at around 4.5 million pounds, and in 1975 at just under 4 million pounds. By 1981, though, the population had been so diminished by overfishing that only 100,000 pounds were harvested. Alewife stocks have slowly recovered since that time, largely due to statewide conservation and monitoring efforts.  Last year, landings totaled around 1.6 million pounds.

 Chris Petersen, left, works with Bruce Connery of Acadia National Park to install a grate at the Somes-Meynell alewife run.Chris Petersen, left, works with Bruce Connery of Acadia National Park to install a grate at the Somes-Meynell alewife run. Credit: Chris PetersenThe alewife population in Maine has been strained by offshore fishing for Atlantic herring, Petersen said, although that seems to be more of a problem in southern New England than it is here.

“A herring midwater trawl can be huge, unbelievably huge,” he said. “Because they’re harvesting millions of fish, you don’t need a very high percentage of bycatch to end up with a lot of alewives.”

The fish that survive the dangers of life in the ocean still face many obstacles when they enter their freshwater runs. Around 52% of historical alewife spawning habitat in Maine is currently blocked by dams and other obstructions. Fish ladders and lifts provide access around some of these dams. In places where the dams are so large there isn’t a fish ladder, alewives must be “trapped and trucked” to the other side of the dam. Of the current habitat, 6% is active only because of trapping and trucking.

Alewives are important both ecologically and from a human perspective. Strengthening their population benefits the fishermen who collect them, the lobstermen who value them as bait, and the watersheds themselves. Alewives play an important role in transporting nutrients between marine and freshwater ecosystems. Additionally, 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.

“Everybody wants more of them,” said Petersen. “The way you get more alewives is by increasing the connectivity [within] your watershed and [improving] water quality if that’s an issue.”

When the alewives begin migrating to the lakes in May, volunteers are essential in surveying the runs. Volunteer hours count toward the COA community service requirement, and Petersen encourages interested students to get involved.

“If you want to come count,” he said, “talk to me and I’ll get you out there.”

Students in Chris Petersen's Aquatic Methods Research class take scale samples and measure alewives in Somesville.Students in Chris Petersen's Aquatic Methods Research class take scale samples and measure alewives in Somesville. Credit: Chris Petersen