Over 100 stranded Dolphins in Cape Cod are now free, rescue teams say − for now

Rescue efforts were winding down Monday after teams freed more than 100 dolphins stranded in dangerously shallow waters off Cape Cod in one of the largest mass stranding events ever witnessed in the area.

As of Monday, there were no more reports of stranded dolphins along the "Gut," a maze-like expanse of gently sloping sand and mud flats west of Wellfleet, Massachusetts, that's a global hot-spot for sea life strandings.

Dolphins and human boaters alike regularly run aground there, said Brian Sharp, marine mammal rescue team director at the International Fund for Animal Welfare. Over the coming days and weeks, Sharp's teams will be on the lookout for subsequent strandings in the area, which he said is likely.

Herding dolphins into deeper water is tricky because the social animals tend to follow one another − like into dangerously shallow waters, which is how the 125 Atlantic white-sided dolphins got stuck in the first place, the International Funds for Animal Welfare said.

"It's kind of like a dog herding sheep," Sharp, 48, told USA TODAY, explaining how if one dolphin goes to the left or right, all the others will likely follow.

Like with boaters, getting stranded feels like a traumatic "car crash" for dolphins, Sharp said. The animals experience high levels of stress and get disoriented, making rescue efforts an urgent challenge, he said. The handful of dolphins that died from the mass stranding was mostly calves, Sharp said, and were less equipped to handle the trauma of getting stranded without water.

On Friday, the big group of dolphins got stranded after swimming into too-shallow, muddy waters in the Gut. Sharp's organization received evidence the mass stranding event happened after "a lot of bait fish" ended up in the small bay the Gut river flows into, attracting the dolphins, Sharp said.

To free the dolphins and prevent deadly sun exposure, about 80 International Funds for Animal Welfare staff and volunteer rescuers turned them right-side-up, herded them on foot as the tides rolled in, and used boats to shepherd the animals into deeper waters.

The cape can be so dangerous for dolphins and other animals because its peninsula causes the coastline to wrap up and around, in a hooked shape, Sharp said. The dramatic wraparound means some animals intending to swim east out into the Atlantic get stuck in very shallow waters or on land, according to the International Fund for Animal Welfare, which has its global operations headquartered in Yarmouth, Massachusetts, along the Cape Cod Bay. Each year, the group responds to about 270 strandings along Cape Cod, the group said.

Friday's mass dolphin stranding near Wellfleet was the largest dolphin stranding incident wildlife officials have observed in Cape Cod going back decades, according to the International Fund for Animal Welfare.

The animal welfare group's Director of Communications Stacey Hedman told USA TODAY that, "125 dolphins in one event is the largest we've ever seen."

As of Monday morning, approximately seven "stubborn" dolphins had been freed, Sharp said. Teams saved approximately 108 over the weekend, and 10 dolphins died before they were able to be saved.

Why did dolphins get stranded on Cape Cod?

Dolphins swim in large groups or pods, and when one dolphin swims in a certain direction, others are likely to follow, according to the International Funds for Animal Welfare.

The 125 Atlantic white-sided dolphins got stranded in an area with large tidal fluctuations and dangerous mud, said Hedman.

Sometimes, if a dolphin is sick, they may get disoriented and swim into a shallow area, but "many of the dolphins and porpoises that strand in this area have no clinically significant pre-existing diseases that cause them to strand," Hedman said.

Hedman told USA TODAY on Monday there was no evidence connecting the latest mass-stranding event to climate change.

However, Sharp said strandings are happening more often because the prey dolphins eat is getting pushed into different places, which can be attributed to changing ocean temperatures, he said.

"The oceans are changing, it's a matter of can these animals adapt quickly enough to that change," Sharp said.