Rare Completely White Risso's Dolphin Spotted Off California Coast

An extremely rare, completely white Risso's dolphin has been spotted swimming off the coast of California.

Tour operator Monterey Bay Whale Watch said, via Facebook, that on an April 26 all-day trip, it was "delighted" to find itself amid 1,000 Risso's dolphins. Among them was Casper, "the beloved all white Risso's."

"Any day spent in the company of this special individual is a good day in our book," it wrote.

Casper is well-known to Monterey Bay Whale Watch as he occasionally visits these waters with his pod, although sightings of him remain rare.

A spokesperson for Monterey Bay Whale Watch told Newsweek: "Our company was the first to spot Casper in August of 2014 as a calf, so he is likely around nine years old now. We were also the ones to determine his sex as male! We see him periodically throughout the year, and he has only been observed here in Monterey Bay!"

Marine biologists at the tour operator believe he is leucistic, but it can be hard to tell for sure.

This is a rare genetic condition that causes a partial pigment loss in the skin, making Casper appear all-white in color. Although the condition is extremely rare, it has been sighted in other animals.

Another whale-watching operator spotted a leucistic orca, who has been nicknamed "Frosty," near Newport Harbour last week,

Leucism is not the same as albinism, a genetic condition that can occasionally be seen in whales and dolphins and causes them to appear all-white in color.

Danny Groves, head of communications at Whale and Dolphin Conservation (WDC), told Newsweek: "Being white may not be due to albinism... Leucism is a pigmentation condition of whiteness with splotchy patches of white, whereas albinism tends to mean solid white or pale yellow coloring. Albinism is a condition that can affect all vertebrates. It is a congenital disorder, meaning it is inherited from the parents, and is characterized by the complete or partial absence of pigmentation in the skin, hair and eyes. This pigmentation is called melanin."

There have been a few albino cetaceans spotted in the wild. An albino bottlenose dolphin was spotted recently swimming off the coast of South Africa. Although it is hard to tell both disorders apart, this dolphin was likely a true albino.

"'True' albinism only occurs if both the parents carry the recessive gene for the condition and the offspring receives both copies of the recessive gene. Depending on the degree of albinism, the individual may have all or some of the following characteristics: white or pale skin (and hair), pink or red eye coloring and, often, impaired vision and hearing," Groves said.

Albino and leucistic animals may be a beautiful and unusual sight to behold in the wild but can cause problems. Groves said that it can lead to less camouflage from predators and also result in unwanted attention from humans.

"Disturbing whales and dolphins disrupts their natural behaviors and can cause them stress," he said.

Since Casper was first spotted, he has been regularly photographed by Monterey Bay Whale Watch photographer Daniel Bianchetta. Bianchetta previously told Mercury News that he is "like a ghost."

"You'd see him sometimes, and then you wouldn't."

For this reason, the name Casper seemed fitting.

Update, 4/28/23, 3:28 a.m. ET: This article has been updated to include a quote from Monterey Bay Whale Watch.

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