Cold Spring Harbor beach site of apparent fish kill, state DEC says

State environmental officials are investigating an apparent fish kill in Cold Spring Harbor on Thursday, in which one area fisherman described seeing “thousands” of dead fish on the beach near his Laurel Hollow home.

“This is a disaster," said the fisherman, Albert Messina, 83. “I’ve been fishing all my life and I’ve never seen anything like this.”

Messina said dead spearing, fluke and porgies floated onto the shore sometime between Wednesday afternoon and early Thursday morning. Most of them later floated into the water again. 

In an email, a representative for the New York Department of Environmental Conservation said that the agency was working to confirm the event and determine the cause of the fish deaths. The deaths may have occurred as storms passed through the area near Wednesday night's low tide, the representative wrote. That combination may have exacerbated low oxygen conditions faster than fish were able to move out of the area.

Christine Suter, executive director of Friends of the Bay, a conservation group focused on Oyster Bay and Cold Spring Harbor, told Newsday those bodies of water are mostly healthy but that it was “not uncommon for fish kills to happen at this time of year,” often because of zones of low oxygen, or hypoxia. Warm water temperatures can aggravate the condition by impeding mixture of the water column, she said. Messina said the surface temperature of the water was 73 degrees when he found the dead fish, a normal condition for the water.

Friends of the Bay's most recent monitoring, on Tuesday, found oxygen levels slightly above hypoxic on the bay’s outskirts and slightly below in the middle. The threshold for hypoxia is 2-3 milligrams of oxygen per liter of water.

Suter said that area waters were mostly healthy but pollution from outdated cesspools and septic systems remains a chronic threat, as it is across much of Long Island. Nitrogen and phosphorus from those wastewater systems contribute to algae blooms that harm water quality and deplete oxygen in the water. Suter said she was not aware of any major nearby blooms.

In August 2022, DEC officials said they had received reports of "mortality events" for menhaden, an important prey species for many predators, in Cold Spring Harbor, Eastchester Bay, Hempstead Harbor, Manhasset Bay and Port Jefferson Harbor. 

Stony Brook University marine scientist Christopher Gobler noted then that some North Shore harbor waters had neared 78 degrees, hotter than he'd seen over 10 years of monitoring. Gobler could not be reached Thursday.