The two marine mammals were found about 100 yards apart on Kealia Beach in North Kihei at about 3 p.m. Saturday, and were transported by Maui Ocean Center staff a short distance to the protected waters of Ko'ie'ie Fishpond at Kalepolepo.

The adult whale was nearly 10 feet long, and her baby was nearly 4 feet long — the size of a newborn calf, according to David Mattila, a rescue specialist with the Hawaiian Islands Humpback Whale National Marine Sanctuary, whose headquarters overlooks the fishpond.

Volunteers supported the two whales in a sling in the water until a veterinarian from the Hawaiian Islands Stranding Response Group could fly in from Honolulu, Mattila said.

At one point Saturday night, the calf bolted from its sling and disappeared into the darkness, Mattila said. The mother whale was released to see if it could draw the calf to shore, but the adult animal was disoriented and swimming erratically, striking rocks, he said.

A decision was made to euthanize the animal at about 9:30 p.m. The calf did not reappear and is presumed dead, he said.

There were no obvious injuries or illness to either animal, Mattila said, and the whales did not appear emaciated. A necropsy was done on the mother whale yesterday, but the results of tissue tests and other samples may not be known for months, he said.

Mattila said natural causes are responsible for the majority of marine mammal strandings.

Pygmy sperm whales are toothed whales that live in the deep sea. The fact that one would strand itself in shallow waters indicates a serious condition with a slim chance for survival, Mattila said.