Marine mammal specialists were closely watching a group of common dolphins in Wellfleet Harbor on Saturday after several dolphins were stranded onshore Friday at Eastham, where one died.
The dolphins attracted attention around 6 a.m. Friday, when a fisherman at Wellfleet Pier sighted a group of 14 dolphins swimming at low tide, said Brian Sharp, stranding coordinator for the Yarmouth Port-based International Fund for Animal Welfare.
Sharp said Wellfleet Harbor is the most common site on the Cape for dolphin strandings because it’s “a hook within a hook,” sheltered within two peninsulas. The animals swim into the harbor around high tide, he said, then get stuck when the tide goes back out.
With tide fluctuation at this point in the lunar cycle averaging around 10 feet, the difference in depth can catch the dolphins by surprise.
“If they don’t stay in the center of the harbor, it can be very dangerous,” Sharp said. “They swim in here with 10 or 12 feet of water, and then six hours later they’re high and dry.”
A team of staff and volunteers from the organization spent much of Friday herding the animals out of Wellfleet Harbor and past Jeremy Point into Cape Cod Bay, finishing around 2:30 p.m.
Throughout the day, three staffers and as many as 25 volunteers were involved in the effort.
The dolphins appear to have then split into two groups, with six swimming into deeper water while the other eight headed south along the coast.
Around 4 p.m. Friday, the team got a call that dolphins were coming onshore at Eastham, south of Wellfleet. They arrived to find one animal had died and seven more were stranded between First Encounter Beach and Thumpertown Beach in Eastham. A necropsy is planned for the dead dolphin.
Using special stretchers, the team lifted the surviving dolphins into a transport trailer, where they were examined and found to be healthy. Plastic identifying tags were placed on the trailing edge of their dorsal fins, like earrings, Sharp said. They were released into the water off West Dennis Beach around 9 p.m. Friday.
About 3:30 p.m. Saturday, the other six dolphins were again seen in Wellfleet Harbor. A staff member from the animal welfare organization was monitoring the group from the Wellfleet harbormaster’s vessel until dead low tide around 7 p.m. on Saturday to ensure that they did not swim into shallower waters.
Because most of the dolphins were under six feet in length, Sharp said the animals appeared to be juveniles, but they were not traveling with parents as very young dolphins would be. They were just “teenagers getting in trouble on Cape Cod,” he joked.