Suffolk County collected water samples Sunday in the Peconic Estuary where tens of thousands of dead fish still lined the shore after a massive die-off.
"The county health department notified the nearest bathing beach and will be doing sampling of the waters," said Justin Meyers, spokesman for Suffolk County, in a statement.
At Indian Island County Park in Riverhead, dead bunker -- also known as menhaden -- were washed on the shore as seagulls lazily picked at them. With the wind coming out of the west Sunday afternoon, only a handful of dead bunker had made their way near downtown Riverhead. Other communities affected were Flanders and Southampton.
Marine scientists said the decaying bunker, if left to decompose in the water, would contribute to decreased oxygen levels -- the suspected cause of the fish die-off.
Christopher Gobler, professor of marine science at Stony Brook University, who researches Long Island's coastal waters, said that while smaller fish kills can happen every year, this one is particularly large.
"Yes, there are some small fish kills every year," he said. "But what's happening is not natural."
He said a U.S. Geological Survey Buoy recorded six straight hours of zero oxygen at a point in the Peconic Estuary on Thursday night into Friday. "Nothing can survive that," he said.
The low oxygen in the water has been exacerbated by algal blooms, so-called red or brown tides, fed by increased levels of nitrogen in the water. Higher nitrogen levels in coastal waters are caused by homes and businesses not connected to sewers, and fertilizer runoff from lawns and farms, according to the county's water monitoring report.
Scott Horowitz, a Southampton trustee, said the town had one crew of four or five who work on maintenance or piping plover programs trying to clean up the dead fish. "Our resources are limited," he said.
While there have been discussions with the Department of Environmental Conservation about a cleanup plan, he said there is no regional plan. He said the trustees are expected to discuss the topic at their regularly scheduled meeting Monday.
Kevin McAllister, founder of the environmental nonprofit Defend H2O, said the decomposing bunker will hurt water quality. "That many fish on the bottom is not a good thing," he said. "Is it practical for some agency to remove them? Of course not. But the notion that this many fish on the bottom is out of sight, out of mind? That's just not true."
Among the bunker carcasses along the shore Sunday at Indian Island County Park were about a half-dozen dead bluefish. Predators like bluefish chase the bunker into shallower waters.