A white Risso’s dolphin known to frequent Monterey Bay looked especially luminous Saturday during an extraordinary Southern California appearance.
Capt. Delaney Trowbridge of Pacific Offshore Expeditions announced the sighting via Instagram:
“Casper the Risso’s dolphin has NEVER been documented outside of Monterey Bay – but today we found him alongside other Risso’s and bottlenose on the front side of Santa Rosa Island.”
Casper the white dolphin next to pod mate. Photo: Delaney Trowbridge
Santa Rosa Island is part of Channel Islands National Park off Ventura and Santa Barbara, more than 200 miles south of Monterey.
Risso’s dolphins, which can measure 10-plus feet, are robust cetaceans that typically travel in groups of between 10 and 30.
They’re born with dark skin that lightens to a pale gray as they age. As adults, their skin boasts scars caused during battles or mating.
Casper, first spotted as a white calf in Monterey Bay in 2014, is either leucistic or albino. But while his skin had a slight film of algae during previous sightings, on Saturday it was pure white.
“Initially I thought we had found Blanco, the other white Risso’s dolphin that I’ve encountered a few times off of San Diego and Catalina Island,” Trowbridge told FTW Outdoors. “Comparatively, Casper is much whiter, Blanco has dark lips and a dark trim on his fin.
“Once we got that closer look it dawned on me, ‘Wow, this dolphin is porcelain white – it wasn’t Blanco.’ ”
Casper next to pod mate with scarred body. Photo: Delaney Trowbridge
Alisa Schulman-Janiger, a researcher, helped Trowbridge determine, based on fin markings, that the dolphin was Casper.
Schulman-Janiger said diatoms that caused the yellowish hue had died off, perhaps in warmer Southern California waters, revealing the sleeker look.
The sighting occurred just days after a white killer whale named Frosty was spotted with other orcas near the Channel Islands.
Pacific Offshore Expeditions was on an all-day Killer Whale Quest when Casper and his pod mates were encountered.