Protecting & Restoring Long Island's Peconic Bays

Peconic Bay Scallop Adult Population Die-Off

November 8th, 2019


During the past week, we have received inquiries regarding the current situation of Peconic Bay Scallops in our waters. We at the Peconic Estuary Program are deeply saddened by the scallop die-off that has transpired in the Peconic Bays. We have been aware of this situation and are working with our scientific partners to gain a better understanding of why the recent die-off of adult scallop populations occurred.

This event likely took place several weeks or months ago and only appears to have affected adult scallop populations. Initial surveys by our partners at Cornell Cooperative Extension, a review of Suffolk County surface water quality data from January to October 2019, and U.S. Geological Survey (USGS) surface water quality data indicate that this occurrence was not associated with a harmful algal bloom like we have seen in years past. There have, however, been higher water temperatures throughout the Peconic region for the past two years – sometimes exceeding 80°F. There have also been low dissolved oxygen levels – a parameter often affected by high nutrients in the water. However, at this time we do not know the exact cause of this die-off.

Unfortunately, the collapse of adult bay scallop populations is more complicated than just the health of our local waters. Increasing global ocean temperatures and warmer water will be a continuing concern as we begin to feel the effects of a warming climate. Warmer waters are more vulnerable to the effects of nutrient pollution – this is possibly reflected by the continued hypoxic and anoxic conditions in the western Bay at the USGS water quality monitoring station in Flanders Bay.  Many estuary ecosystems are changing from climate change and this is also affecting regular predator-prey cycles. The Peconic Estuary Program has some of the best data available and is looking into this as well.

The Peconic Estuary Program remains committed to our strong local partnerships – working together to solve the water quality, habitat, and climate change issues on the East End of Long Island. We continue to deliver sound science so our communities are informed.

Photo Above: Christie Pfoertner


The Peconic Estuary received designation as an “Estuary of National Significance” by the U.S. Environmental Protection Agency (EPA) in 1992, and the Peconic Estuary Program, a collaborative partnership of local, state, and federal governments, citizens, environmental groups, businesses, industries, and academic institutions, was established. The Peconic Estuary Program is one of 28 National Estuary Programs around the country supported by the U.S. EPA’s Clean Water Act.

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