OLD LYME – The deep water of Black Hall Pond this spring has become a laboratory where environmental officials are trying to revive a once-prolific species of bait fish that has suffered a mysterious and precipitous decline across the state in recent decades.
Known as the Alewife, the silvery, foot-long herring is a major draw for fisherman and predators such as striped bass and osprey, and once were so prolific that they choked adjoining streams with their numbers during migrations.
One contributor to their decline here was a series of beaver dams that blocked their spawning route between Long Island Sound and the 16-acre pond, which at an average 20-foot depth is an ideal breeding area.
But even as beavers more recently have exited or been trapped and their dams breached, the Alewife population has been on a mostly-downhill roller coaster that saw a huge drop in their numbers in just the last three years.
“It’s really hard to point a finger at one specific problem,” Kevin Job, a fisheries biologist with the state Department of Energy and Environmental Protection said during a Thursday visit to the pond, where he has begun stocking what he hopes will be more than 1,500 adult Alewives. “Water quality is good, we’re removing beaver dams and building fishways and our numbers are, unfortunately in some places, the worst they’ve been in the 30 years we’ve been monitoring them. That’s crazy.”
The fish has been on the state’s protected list of species for about 20 years, and Job suspects that whatever is causing the statewide decline is happening during the time the fish are out in the Sound.
The Black Hall Pond restoration attempt began with an initial stocking of about 800 Alewives earlier this month that were bred in Bride Lake in neighboring East Lyme, long used by the state as a hatching area.
But even there, Job said, this spring has seen only about 100,000 adults return to the lake from the Sound via Bride Brook to spawn, about a quarter of the returning population seen in 2019.
“We saw them leaving and going downstream in the fall and it looked fantastic,” he said. “But unfortunately, it doesn’t seem like they’re coming back. Whatever happened, whether it was at sea or here, we don’t know. But it looks like it was at sea, and we can’t control what happens out there.”
Black Hall Pond is one of about 20 sites around the state that DEEP is stocking with Alewives this year, including nearby Rogers Lake.
Job said he had hoped to transfer about 40,000 fish to the sites, but expects that he may not be able to collect much more than 5,000 for distribution.
Several conservation commission members joined Job at the pond Thursday to discuss the project, including Gary Gregory, Traci Russell and Nicole Kabel, who have helped researchers from Yale University collect water samples from it in hopes of finding clues to the Alewive’s decline.
“We don’t know what a lot of these waterways are composed of because there’s only a handful that they actually have reports on,” Kabel said. “So doing a more fruitful study here is a good example for somebody else to be able to do it in another spot up the coastline and will be helpful to make it a more productive comeback.”
Despite the array of issues and mysteries surrounding the situation, Job remains hopeful that the effort will pay off.
“This pond is deep, it’s natural, and it historically had a very big run,” of the baitfish, he said. “Each fish we put in here can have 100,000 eggs, so it only takes a few and things could get right back on track again.”
That would be long-welcome news for 85-year-old Dave Berggren, who grew up on the pond and still lives there, and who hosted the group on Thursday after urging officials to investigate the situation.
He recalled that as a boy he and his friends would watch as countless thousands of Alewives, which he calls “buckeys,” jammed the entrance to the pond during migration.
“They would run so heavy that they pushed themselves out of the water and would be flopping on the edge of the woods,” he said. “And we would ride up on our bicycles and put them back in the water. This went on day after day after day.”