CORNWALL Wildlife Trust marine conservation officer Abby Crosby said a post-mortem examination at Exeter University was expected to reveal why the rescued dolphin later died.
The trust's Marine Strandings Network is investigating and the carcass will be examined as part of a national programme called the Cetacean Strandings Investigation Programme.
"Sadly, these incidents do occur," she said. "These are very rare animals and we only have a very small pod left in the county, which means it's even more important to make sure we get information as to how it died."
The 24-hour stranding hotline can be contacted on 0345 201 2626.