Whale watchers in California's Monterey Bay have caught up with a familiar white dolphin calf. The colourless youngster is a Risso's dolphin, and photo analysis reveals it's the very same individual who made its first appearance in this area back in 2015!

The team at Princess Monterey Whale Watching (PMWW), who captured this footage, were ecstatic to see the dolphin looking strong and healthy. White whales face a unique set of challenges in life, and given recent orca predations in the bay, this calf may have been at especially high risk. 

Based on its blotchy appearance, initial reports suggested the dolphin could be leucistic. This genetic condition (also known as "piebald") results in a partial loss of the pigment melanin, and animals born with it can sport a range of "patchwork" prints –the pigment cells in the eyes, however, are not affected. Albinism, on the other hand, involves complete loss of pigment. True albino animals tend to have very pale eyes (often pink or red, as the blood vessels show through). Photographs from past sightings confirm this Risso's baby is indeed a true albino.

The yellow markings you see on the calf's skin are not its own flesh; they're the result of tiny planktonic algae called diatoms growing on the skin. The location and abundance of these diatoms, however, changes over time, so they aren't much use when it comes to identifying an albino dolphin. Instead, Kate Cummings and the crew of Blue Ocean Whale Watch (BOWW) looked to the mother to make the match.

"We looked at scars and pigment on its mother's dorsal fin from both sightings," they wrote on Facebook. "Look for subtle scarring and pigment, especially the small scars towards the tip of the dorsal fin."

Image: Kate Cummings/Blue Ocean Whale Watch

Some commenters have pointed out that the calf in PMWW's footage looks smaller than the individual previously seen in the bay, but former NOAA marine mammal observer Alisa Schulman-Janiger explains that's likely just an illusion. 

"That can be an artifact of lens size [and] angle," she explains. "The calf's dorsal fin shape also matches; I was looking at all available images this afternoon. The mom ID match sealed the deal."

Risso's calves typically nurse for 18 months, and the gestation period is nearly as long. It's extremely unlikely, then, that this mature female weaned an albino calf and gave birth to a second one within just a two-year period. 

"We're hoping we don't have to wait years to see it again," adds the BOWW team. "Maybe it'll stick around! We'll definitely be on the lookout."

Image: Princess Monterey Whale Watch/Facebook
Image: Princess Monterey Whale Watch/Facebook
Image: Princess Monterey Whale Watch/Facebook
Image: Kate Cummings, Blue Ocean Whale Watch/Facebook

The Risso's calf wasn't the only famous face to return this week: a dappled dolphin known as "Patches" was seen near Southern California's Long Beach! Find out more about this two-toned wonder here.


Top header image: Tim Ellis/Flickr