By Jan TenBruggencate
Advertiser Columnist

Herman Melville's fictional white whale in "Moby Dick" was a sperm whale, a rare member of that species that lacked pigmentation.

There are naturally white whales, notably the beluga, which starts life gray and turns white as it gets older. But white whales are unusual. What about white humpbacks?

They appear to be exceedingly rare. They were unheard of until one was spotted swimming in the Pacific — an all-white humpback that has been seen repeatedly since 1991.

The animal appears annually off the coast of Australia. It is part of the Southern Hemisphere stock of humpbacks, which appears to be distinct from the North Pacific stocks that visit Hawai'i.

Paul Forestell, of the Pacific Whale Foundation on Maui and Southhampton College in New York, said the animal may be an albino, although none of the roughly 50 spottings has been sufficient to identify the pink eye coloring that would confirm this. Partial white coloring is far more common in Southern Hemisphere humpbacks than in the North Pacific, and it is possible the white whale is simply white-skinned without being an albino.

"There has never been a documented occurrence of an albino humpback whale anywhere in the world," he said.

"There have been a number of other species — about 20 — for which albinos have been reported, including bottlenose dolphins, pilot whales, killer whales, spinner dolphins, and sperm whales. The occurrence is very rare, and often reports may not be entirely accurate — there are a number of diseases that can cause light shading rather than true albinism."

Forestell said it is unlikely that Hawai'i whale watchers will ever get a look at this particular whale.

"The equator forms a natural barrier, with the southerly animals spending June — their winter — in tropical breeding waters near the equator, while the northern animals are feeding in Alaska," he said.

When the humpbacks in the North Pacific head south to the tropics in our late fall and winter, the southern animals are heading south to Antarctica for their summer.

The white humpback appears to be a male, and may now be in its late teens. Normal humpbacks can live for 35 to 50 years, but it is unclear whether it will live a full life.

"The most recent photos I have seen (from a couple of years ago) show some ugly bumps and swellings and cysts around the blowholes — the area of the body that must be exposed to the sun every time the animal breathes, Forestell said. "I don't imagine the prognosis for avoiding skin cancer is all that great. The frequency of spotting the whale has seemed to decrease over the past three or four years — no reports of it this year — although it's hard to guess what that may mean."

Jan TenBruggencate is The Advertiser's Kaua'i bureau chief and its science and environment writer. Reach him at (808) 245-3074 or jant@honoluluadvertiser.com.