Field research has started into an indigenous freshwater salmon species known as "kunimasu" that was thought to have gone extinct about 70 years ago but found in Lake Saiko late last year.

From The Mainichi Daily News

In the study, to be conducted on the shores of the lake at the base of Mt. Fuji through the end of March, local officials and fishermen will try to collect carcasses of the salmon. Females of the species, called black kokanee in English, are known to die after laying eggs usually in February or March.

Four carcasses of fish believed to be kunimasu were found in January, they said.

The central Japan prefecture's fishery technology center will freeze and examine the carcasses collected to figure out if they are those of the salmon species.

The Kunimasu or Black Kokanee Salmon from Japan

"It is not easy to find (the carcasses of kunimasu)," said Kunio Sasuga, a 43-year-old official of the town of Fujikawaguchiko where the lake is located.

He was among 16 people who took part in what turned out to be a fruitless hourlong search for carcasses on the first day.

The kunimasu had earlier been seen only in Lake Tazawa in Akita Prefecture, northeastern Japan, and was thought to have gone extinct after an inflow of acidic water into the lake starting around 1940.

It was discovered at Lake Saiko in mid-December.