Killer whales were sighted during a whale watching tour on 24 July in the Kunashir Strait, a stretch of water between the Hokkaido and Kunashir Islands.
As noted by an employee of the travel company Gojiraiwa-Kanko, one of the killer whales has already been seen off the Japanese coast a couple of years ago, and now another young individual has joined it.
They swam near the surface of the water, accompanied by killer whales of the usual colors.
Experts believe that the white color is indicative of leucism in killer whales. With this mutation, animals show a partial loss of pigmentation.
Sometimes leucism is mistaken for albinism, but, unlike albinism in leucism, pigment cells are absent altogether.
While albinism exclusively affects melanin, leucism causes a reduction in all types of pigments.
Killer whales and whales used to be so rare that they were considered a myth, but today they are becoming more common. Zoologists are aware of at least five white killer whales living today.
It is not entirely clear why they are becoming more common, but scientists speculate that this may be due to declining numbers and is a sign that the species is in trouble.
As the population of a species declines, so does its genetic variability, because the remaining animals have fewer potential partners to choose from.
This leads to the emergence of rare genetic disorders that interfere with the ability of animals to survive in the wild, threatening to accelerate the extinction of the species.
While it is not known what effect leucism has on killer whales, it makes them more visible, which can hinder their hunting abilities and attract unwanted attention from rivals.
