A sighting of a white harbor porpoise was reported June 8 in the Baltic Sea, near Denmark. Fortunately, the person who sighted the extremely rare marine mammal recognized it despite being a layperson and was able to record the sighting on camera.
The Dodo reports that sightings of white harbor porpoise are so rare that only 15 sightings have been reported in the last 100 years.
Fabian Ritter, a marine biologist with the Whale and Dolphin Conservation (WDC), described the latest sighting as “extraordinary.”
He also pointed out the significant fact that the individual behaved in an unusual manner.
“This animal appears to be playing with the vessel, swims alongside it and rides the bow wave. That is quite unusual behavior for a harbor porpoise. I’m not saying it’s impossible, they are usually a wary species, and not especially interested in vessels. This is quite curious behavior.”
White harbor porpoises, according to the Dodo, are distinguished in color from normal, darker-colored individuals due to genetically determined absence of pigmentation. The cause of the condition in white harbor porpoises ranges from albinism to leucism, according to Discovery.
The individual spotted recently in Denmark was identified as “leucistic.”
Like albinism, leucism is a genetic condition characterized by pronounced lack of skin pigmentation. However, the degree of lack of pigmentation is less marked than in albinism.
“In the past 100 years, only a small number white porpoises have been documented worldwide, ranging in causes from true albinism to leucistic (reduced pigmentation) to hybridization with another animal.”
A recent study which reports sightings in 1911, 1928, 1929, 1937, and 1988 in Ukraine, Scotland, Ireland, and Denmark, highlights the extremely rare occurrence of sightings, according to the Dodo.
Sightings were reported in the Salish Sea, Washington, in 2007, and near San Francisco’s Golden Gate Bridge in 2011.
According to Discovery, the individual sighted in the San Francisco Bay area on three different occasions was named Mini-Moby after Moby Dick, the fictional white whale character from Moby Dick; or, The Whale by Herman Melville.
Mini-Moby caught the attention of marine biologists and conservation experts because of his unique color, being mostly white but with some dark strains in the dorsal fins and blowhole.
“A GGCR paper, ‘First Record of Anomalously White Harbor Porpoises from the Pacific Ocean,’ characterized Mini-Moby’s condition as leucistic and also noted these animals appear to have a normal life span and despite their unique color don’t appear to be ostracized by their peers.”
The 2007-2011 sightings were also special because they marked the return of harbor porpoises to the San Francisco Bay after about 65 years absence.
Leucism and albinism occur in other marine mammals besides porpoises. The conditions have been observed in orcas and in humpback whales. A particular humpback whale individual called Migaloo has achieved fame among experts and conservationists.
Although, the condition attracts human attention because of its rarity, leucistic individuals suffer survival disadvantage. The condition deprives the individual of normal defensive camouflage.
Leucistic individuals also tend to suffer vision, hearing, and skin disorders.
Although, dark-colored harbor porpoises are not considered endangered species by the IUCN, in 2013, the Baltic Marine Environment Protection Commission, also known as the Helsinki Commission or HELCOM, listed two Baltic Sea subpopulations respectively as vulnerable and critically endangered.
[Image: YouTube/Peter Hofmann]