VIDEO: Risso’s dolphin found dead in San Francisco Bay was malnourished, dehydrated


SAN FRANCISCO (BCN) — Scientists at the Marine Mammal Center in Marin County determined that a Risso’s dolphin found dead in San Francisco Bay on Wednesday was severely malnourished and dehydrated because it wasn’t eating.

The determination was made after scientists conducted a necropsy Wednesday afternoon shortly after the cetacean was retrieved off of mudflats in the Bay near San Francisco International Airport.

“It hadn’t eaten for quite some time,” Marine Mammal Center spokesman Giancarlo Rulli said.

Why the dolphin was not eating, which is also how it hydrates itself, scientists don’t know yet.

But the scientists will be sending tissue and organ samples for a histopathology report to determine whether the dolphin had a disease that was causing it to avoid eating. The histopathology could take several weeks.

Rulli didn’t rule out the possibility that a lack of food in the ocean was the reason the dolphin was malnourished, but because Risso’s dolphins rarely swim in San Francisco Bay, scientists suspect the dolphin had a disease.

The animals typically swim in the ocean in pods of other Risso’s dolphins.

“To be traveling alone in San Francisco Bay is extremely unusual,” Rulli said.

Just before noon Wednesday, scientists confirmed that the Risso’s dolphin was dead after it was reported stranded on the mudflats Tuesday.

A rescue team failed to find the dolphin during a day-long search Tuesday, but Marine Mammal Center officials believed the dolphin had died because it is not designed to be on land.

Researcher Bill Keener with Golden Gate Cetacean Research, a nonprofit devoted to the study of Bay Area dolphins, porpoises and whales, saw the dolphin several times between Saturday and Tuesday circling in
shallow water before it got stranded about 400 meters from shore.

Risso’s dolphins are seen so infrequently in waters other than the ocean that rescuers with the Marine Mammal Center have responded to only 10 sightings of them in the center’s 41-year history.

Risso’s dolphins can be identified by their rounded heads, curved dorsal fins near the middle of their backs and dark gray coloring with white scarring that can be so extensive the mammals appear white.

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