Underwater cameras track the humble alewife in hopes of saving him
OLD LYME – Submerged in the shallow but rugged flow of an outlet between Black Hall Pond and Long Island Sound, the camera takes a picture once a minute, day and night.
The 24/7 automatic photo shoot is designed to track the numbers and migration pattern of a small, humble-looking type of herring known as an alewife as it travels downstream after spawning in the pond and while returning to the saltwater habitat where it spends the most time. of their relatively short life.
Gaspereaux play an essential role in the food chain in water and on land, and their once abundant population has declined sharply in recent years for reasons that are still unknown. Alewife have been on the state protected species list for about 20 years.
The GoPro camera is one of six such setups that UConn graduate student and Branford resident Mike Burgess is setting up here and in the waterways of East Lyme, Old Saybrook and Mystic to try and track what’s going on. behind the population decline and how to fix it.
“Alewife grow and enrich in saltwater systems, then they swim out here to spawn,” Burgess said Monday as he stared into the camera just above a short rocky drop in the creek, which serves as a fish ladder for adult alewife to reach the 16-acre Etang not far upstream. “It provides food for largemouth bass, turtles, birds, raccoons – they eat the young and they eat the eggs.”
Burgess straps on her waders and visits each of the six sites every other day, retrieving flashcards from the camera and bringing them back to campus, where undergrads manually paint each image and tally up the number of fish caught – information basis for an extrapolation of global migration.
Burgess is working on the project under the supervision of Professor UConn, Dr Eric Schultz and the Department of Energy and Environmental Protection, which this spring supplied Black Hall Pond with approximately 1,500 adult alewife in the part of the restoration project in conjunction with the city’s Conservation Commission.
Each female can lay up to 100,000 tiny eggs that stick to the surface of the pond bottom, which decades ago was filled with fish.
Tracking when adult fish leave each of the six ponds and streams it monitors — which typically happens between June and October — will help researchers determine when and where to focus their annual conservation efforts.
“We’re trying to figure out when they’re leaving in terms of the season and on a daily scale,” said Burgess, who is pursuing studies in ecology and evolutionary biology. “Do they leave at dusk, do they leave at dawn, do they leave at noon? It’s important to see how this varies from system to system when we look at preservation methods.
Burgess witnessed a massive migration to the Sound earlier this summer at Lake Bride in East Lyme, long used by the state as a breeding ground for alewife, including those stocked in Black Hall Pond this spring.
“We saw between 15 and 20,000,000 leave around five in the morning two days in a row,” he recalls. “It was just fish as far as the eye could see.”
Still, the roughly 150,000 adult alewife that swam upstream from the ocean to the lake this spring to spawn was about half of last year. Even smaller numbers have been recorded at some of its other sites.
The Burgess and State DEEP researchers say there is no firm theory as to why the population has declined so sharply. But there is much speculation that a major factor could simply be that they are caught at sea by fishermen who use them as bait while other species of bait are declared banned, as happened l ‘last year.
A population survey of Black Hall Pond by a Yale University team estimated that about 7,000 adults were present in mid-June, several weeks after state officials stocked them.
“We also discovered that the pond already had a population of landlocked alewife,” said Yale researcher Andrew MacDonald. “They are the biggest enclaves I have ever seen. We also caught largemouth bass, yellow perch, bluegill and lots of black crappie.
Gary Gregory, a member of the city’s Conservation Commission, one of the project’s driving forces, observed Burgess’ work on Monday and said he was encouraged by the results so far.
“They’re doing really well in there,” Gregory said, referring to Black Hall Pond. “Alewife are eaten by just about every fish in the Sound. If you lose the gaspereau, the fish will have nothing to eat. So it’s really essential for sport fishing.
Gregory was also encouraged by the relatively strong water flow through the outlet below the pond on Monday, which produced a persistent babbling as it moved through dense vegetation towards the strait.
“This stream is flowing and we are in a drought. Are there any other of your streams flowing? he asked Burgess.
“No – they’re all dry,” Burgess replied. “Two of the sites I work on have actually been dry since July 4, I believe.”
“That means this one has more luck in a drought year than anything else,” enthused Gregory. “We could have a gold mine here.”