Cape Cod dolphin strandings in worst year on record, scientists searching for answers

An unprecedented bad year for dolphins stranded on Cape Cod beaches may be related to changing food availability for dolphins due to rising ocean temperatures, researchers say. Scientists hope to curb it.

Massachusetts’ Cape Cod Peninsula, beloved by beach tourists and seafood lovers, has a long history of stranding marine mammals. Part of the reason is the dramatic changes in the tides, which can trap wayward dolphins if they get too close to shore.

But this year is different. The International Fund for Animal Welfare, which responds to marine mammal strandings, said Thursday it has responded to 342 live stranded dolphins this year, five times the annual average of 67.

An already bad year got worse earlier this month when the organization was inundated with inquiries about beached dolphins. The group said more than 50 animals were stranded on multiple beaches and waterways in the past week.

Brian Sharp, the group’s marine mammal rescue team leader and a trained biologist, said the group’s resources and supplies were being stretched to the limit by the mass strandings. Scientists are still trying to determine the cause of the stranding, but they noticed small fish, which the dolphins eat in large quantities, swimming near the shore, he said.

Sharp said the dolphins appear to be putting themselves at risk as they pursue their food source.

“The effects of climate change on ocean temperatures and salinity will affect prey fish stocks,” he said. “As part of the food web, there’s a kind of ripple effect, a cascading effect, throughout the food web that ultimately leads to marine mammals.”

Cape Cod is located near important dolphin feeding grounds, and the peninsula is popular with summer whale watchers due to its diversity of species. Most of the stranded dolphins are common dolphins, white-tailed dolphins, red pilot dolphins and bottlenose dolphins, Sharp said.

Of the 342 stranded dolphins, 293 were able to be released back into the wild, Sharp said. More than 90 additional dolphins were found dead when stranded, he said.

This year’s strandings include a summer mass stranding of more than 100 dolphins that rescuers say is the largest of its kind in U.S. history. Headlands can be difficult for animals to navigate due to sloping sandbars, hooked shapes and sticky tidal flats.

The factors influencing strandings are complex, but it’s clear that changing climate is moving prey and predators to new areas at previously unexpected times, said conservation group Whale and Dolphin Conservation. said Regina Asmutis-Silvia, executive director of North America.

“Recently, the land around Cape Cod has been marked by unseasonably warm temperatures, a reminder that we are facing a changing climate. But that change is not just on the coastline; it is also being felt in the ocean.” she says.

The International Fund for Animal Welfare said in a statement that rescue efforts this month were complicated by rough winds, waves and cold temperatures. The dolphins that stranded this month may have been part of the same pod or pod, but it is still unclear why the pod stranded, the group said.

“Cape Cod has always seen more live dolphin strandings than anywhere else in the world, but this year the numbers have reached historic highs,” the group said in a statement.

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