Rescuers pulled four dolphins from marshland in Wellfleet and found another dead after a pod swam into shallow water at low tide Thursday.
Witnesses reported dolphins at the mouth of the Herring River about 8 a.m. Michael Booth, a spokesman for the Yarmouth Port-based International Fund for Animal Welfare, said the organization dispatched staff and volunteers who found dolphins in Wellfleet Harbor.
The team used pingers that emit a high-frequency noise and moved its boat in a zigzag pattern to herd three dolphins into deeper water, Booth said. The Wellfleet harbor master stayed to ensure the animals didn’t head toward shore.
Rescuers returned to the Herring River and found four other dolphins stranded in marshland. Booth said this area, a hook within the larger hook of Wellfleet Harbor, is a common site for strandings.
“It’s sort of the worst place for dolphins to be in,” he said. “so every time we hear a report of dolphins in that area, we know that there’s a good likelihood they’ll wind up stranded.”
The team lifted the dolphins from the mud in slings and carried them on stretchers to a trailer. They examined the animals and determined they were healthy, then transported them to Herring Cove Beach in Provincetown and released them, with help from National Park Service volunteers.
Rescuers then returned to Wellfleet Harbor and found a dolphin that appeared to be part of the same pod as the others but had died hours earlier. The cause of death was unclear, but Booth said dolphins sometimes die in strandings because they can’t regulate their body temperature outside the water, and their organs have difficulty with the greater effect gravity has on land.
Cape Cod is one of three prime spots in the world for dolphin strandings, Booth said, alongside areas in Australia and New Zealand.
Booth called 2012 a “breakthrough year,” saying the number of common dolphin strandings on the Cape had risen to 262 so far, well above the annual average of 35 to 38. The organization has dealt with more than 300 marine mammal strandings this year and is working with other agencies to seek the underlying causes.
Booth said volunteers would return Friday to see if any dolphins had returned to Wellfleet Harbor.