` ` It 's the largest single - species event '' in the Northeast , a marine mammal expert says . Only 37 of 129 animals have survived to be released , says IFAW 's John Moore . ` Necropsies have been done on the animals ; no cause has been determined . Some of the released animals have been tracked north of Cape Cod , where they belong .
` ` It 's the largest single - species event '' in the Northeast , a marine mammal expert says . Only 37 of 129 animals have survived to be released , says IFAW 's John Moore . Necropsies have been done on the animals ; no cause has been determined . Some of the released animals have been tracked north of Cape Cod , where they belong .