This silvery menhaden, several inches long, washed up dead on the marshy edge of the Quinnipiac River, as an osprey shrieked warnings into the air.
Fish like this one have been dying in the thousands, amid an apparent outbreak of “whirling disease.”
Over Memorial Day Weekend, thousands of dead Atlantic menhaden —a 10-to-14-inch schooling fish—were found along coastal waters of the Quinnipiac River, Clinton Harbor, lower Connecticut River and part of the Thames River. The state Department of Energy and Environmental Protection (DEEP) reported the mass deaths appear to have resulted from the viral “whirling” disease, which can spread swiftly through a school of fish.
Mucking around in the Quinnipiac Meadows Nature Preserve marshes this rainy Tuesday afternoon, this reporter found two dead fish near the river trail’s bird blind, an elevated manmade nest. East side neighbors have found many more.
New Haveners called the state to say they had seen the “kills,” or die-offs, most often near the Grand Avenue Bridge, said David Simpson, director of the state DEEP Marine Fisheries Division.
“In each one of these places, what people have witnessed is fish struggling at the surface, in a spinning behavior,” Simpson told the Independent. Whirling disease “seems the most logical answer right now.”
Yale ecologist Mary Beth Decker saw a few along the marsh edge near Sound School in City Point, but didn’t stop to take a closer look. A specialist in coastal ecosystems, she said the disease is a “natural part of the ecosystem,” sparked by a spike in menhaden populations. “I see it as part of a natural system.” People in the region colloquially call this specific fish “bunker,” she said.
For the past two years, the menhaden population has grown in southern New England and New York waters, likely because of rules limiting their harvest. “We’ve taken good steps in managing the fisheries,” Simpson said.
A few people who walked through the preserve Tuesday morning messaged Justin Elicker, who heads the New Haven Land Trust, to let him know the disease had hit home.
One person saw “literally dozens” of dead fish in the water and washed up on the marsh edge in Hamden’s Quinnipiac River Marsh Wildlife Area.
Another reported a “fish kill” at the entrance to Hemingway Creek at the west side of the nature preserve, “along the bank running south.”
People use the Atlantic menhaden for animal feed or as bait in fisheries. They also are “important forage for things like striped bass and bluefish,” as well as mammals like humpback whales, Decker said.
Simpson said there’s no reason to be concerned about “human health consequence” from the disease: “If it were something to be concerned about, you would see other species affected. If it were something toxic, we’d be dying. That’s not the case here. We’re considering now whether to do some further studies and see if we can tease out what the cause there is,” he said.
The state has been asking people to notify officials about the kills, in order to get a sense of the scope of the disease.
“We don’t have a very good handle on many things about the marine environment, because people are not out there at all places at all times doing those studies,” Decker said. “It’s important to get information as it becomes available.”
Whirling disease gets its name from its effect—in the later stages of the disease, fish can be seen whirling at the surface of the water. Atlantic menhaden mass deaths also happen naturally during warm summer months, when large schools run out of oxygen in the water and suffocate.
In the summertime, many of these fish end up floating towards beaches and shorelines “all over the place,” Simpson said. In this case, those that haven’t found their way to land are sinking to the bottom.