"Every year we have dolphin deaths," Schoelkopf said. "We won't speculate on a cause until the lab results come back."
Schoelkopf said that sending the dolphins for necropsies is normal any time large marine animals are found.
Though dolphin and other marine animal deaths are not uncommon, experts say it is unusual for so many to wash up in such a short time.
"If it continues like this, we'll definitely investigate more," said Mendy Garron, a regional marine-mammal stranding coordinator with the National Oceanic and Atmospheric Administration.
If the dolphins died of disease, a pathologist can study tissue samples and determine whether the disease was viral or bacterial. "It's a very tiered approach," Garron said.
The postmortem examination is just one part of an investigation that can uncover other trends, Garron said.
This year, officials have found an increase in the number of animals off New York and New Jersey, which could affect prey distribution in the ocean.
"It's like piecing a puzzle together in many ways," Garron said.
Each dolphin was sent to the University of Pennsylvania's New Bolton Center in Chester County for examination.
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