Number of dolphin strandings surpasses annual average in less than a month; cause remains a mystery

By Colin A. Young, Globe Correspondent

In less than a month, 129 common dolphins have stranded themselves on the shores of Cape Cod, more than three times the annual average, officials from an animal welfare group said today.

Katie Moore, manager of marine mammal rescue and research for the International Fund for Animal Welfare, said the strandings since Jan. 12 represent the largest single-species stranding on record in the northeastern United States, and more are expected.

“We are staging folks today, staff and volunteers, out on the outer Cape in anticipation of more dolphins coming in this afternoon,” Moore said in a telephone conference call with the media today.

Of the 129 dolphins that have stranded themselves on the 25-mile stretch of coast between Dennis and Wellfleet since mid-January, the group successfully released 37 dolphins into deeper water; 92 have died.

Moore said the common dolphins the group has released appear to be out of imminent danger. The group has attached satellite tracking tags to some of the dolphins and it also monitors reports of sightings from other agencies.

“We have had reports of up to three or four hundred animals in the bay at one time, though last week there were two hundred in the bay,” she said. “In some respects, I don’t know if I want to know how many [dolphins] are still out there.”

The number of strandings, and the lack of apparent cause, have bewildered rescuers.

On Friday, Moore briefed members of Congress on the rash of strandings and appealed for federal assistance in determining a cause of the historic event. The group has completed nine necropsies, but has not been able to pinpoint a potential cause of the strandings.

“We’re looking at, ‘What are the demographics of the stranding event?’ We want to find out if there is a pattern there,” Moore said. “What we are seeing does not indicate any pattern of disease or injury or lesions that would indicate one particular cause for this event.”

Moore said weather could be playing a role in the strandings.

“If we have different weather patterns, we could have a different distribution of prey,” she said. Moore added that all the stranded dolphins have had empty stomachs.

Along with Australia and New Zealand, Cape Cod is one of the top three stranding locations in the world, according to IFAW. Moore said the Cape’s hook shape and gently sloping beaches, along with the social nature of dolphins, contribute to the danger for dolphins and other marine mammals.