An estimated 11,000 juvenile and adult bunker fish died after they entered Mill Pond in Centerport, became trapped and succumbed due to low oxygen levels, Huntington Town officials said.

The fish kill is the largest seen in the town since a mass die-off in Cold Spring Harbor 30 years ago, spokesman A.J. Carter said.

“Too many fish came in and the tide went out and they got trapped,” he said Friday. “This is a natural occurrence. It happens this time of year.”

Most of the fish, also known as menhaden, are clustered in an area along the pond’s shore near Our Lady Queen of Martyrs Church. The dead fish include about 1,000 adults and 8,000 to 10,000 juvenile fish smaller than 2 inches.

Gloria Wertheimer, who is retiring president of the Centerport Harbor Civic Association, said she reported the fish kill Thursday and is avoiding the area.

“The smell is just unbelievable,” she said.

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After talking with state Department of Environmental Conservation officials, Carter said the town decided to close the tidal gates between Mill Pond and Centerport Harbor to keep the area flooded in hopes that the dead fish will float farther into the water body and sink.

“Right now our belief is that nature should take its course,” he said. “While we’re watching this, we’re evaluating other options.”

Spencer Kriegstein, 13, of Huntington, looks over the edge of Mill Dam in Centerport on Friday, Aug. 26, 2016, after thousands of dead bunker fish died and washed up on the shore. Photo Credit: Newsday / John Paraskevas

Chris Gobler, a professor with Stony Brook University’s School of Marine and Atmospheric Sciences, said in an email that the fish kill “makes sense” because North Shore monitoring devices showed oxygen levels dropping to zero after last weekend’s rains.

DEC spokesman Sean Mahar said in a statement that the exact cause of the die-off is unknown, but such events tend to happen in warmer months when oxygen levels are low and the energy used by fish increases.

“In these conditions, fish caught in these low dissolved oxygen areas can asphyxiate and a fish kill results,” he said.

Earlier this week, Nassau County crews collected, bagged and disposed of dead bunker fish found in Silver Lake in Baldwin, public works spokeswoman Mary Studdert said.

Last year, a spike in algal blooms and low oxygen levels were blamed for the deaths of 300,000 menhaden in three separate fish kills along the Peconic River.