Obiramepedia
2022/01/15
The names
| Scientific name | Parahucho perryi |
|---|---|
| Japanese name | itou |
| Ainu name | ciray, tosir, operype, yayattecep, siacep |
| Local name | OBIRAME, oherybe, ito, ido, ciray |
| English name | Japanese Huchen, Sakhalin taimen |
Description
Size
They are up to 90 cm long and usually weigh 10 kg. The largest one, about 210 cm length was recorded in 1937 at Tokachi River. Recently few Japanese Huchen can grow over 100 cm. Japanese Huchen is the largest freshwater fish in Japan.
Proportions
Japanese Huchen is slenderer than other trouts and salmons. Some Japanese Huchen might connect you on a submarine.
Coloration
Japanese Huchen has greenish brown above, with silver midbody, white below. A lot of black fine points cover the whole body except below. The male turns vivid red while spawning.
Teeth
Japanese Huchen has a big mouth and a strong jaw. Also Japanese Huchen has countless teeth with keen edges.
* This article was written by the Obirame Restoration Group.
Distribution and biology
Parahucho perryi are found in Hokkaido island of Japan, Sakhalin island of Russia, the east coast of Russian mainland, and Kuril islands. The Aomori population live in the north part of Japanese Honsyu island had become extinct in early 20 century. In Hokkaido, they live in the slow streams run through wetland such as Konsen, Sarufutsu and Sarobetsu, or some lakes. At present, the southernmost population lives in the Siribetsu River, but one Japanese Huchen was cought in the Syubuto River adjoin the Shiribetsu in 1988.
The hucho family except the Japanese Huchen are found all over the Eurasia Continent, such as the taimen (Hucho hucho taimen ) in the lower Amur River and other Siberian rivers, the huchen (H. hucho ) in the Donau River, the Sichuan taimen (H. bleekeri ) in the Changjiang, and the Korean taimen (H. ishikawai ) in the Yalu, Changjin, and Pujon Rivers.
Fishes belong to Hucho family don’t go down the river but the Japanese Huchen is an exception. Some individuals stay in the brackish waters or the coastal area. The Japanese Huchen generally spend every summer in the middle or upper side of the river, and go down in the late autumn to next spring. They become active after the ice thawed, staying under the structures such as the fallen trees in deep pools of the bends. They swim to the shallows and rapids after the water temperature rising over 10 ℃.
The Japanese Huchen breed in the spring. They spawn March - May. They needs long time to spawn after hatching out. Female Japanese Huchen of 6-7 years and 60 cm long breed for the first time. The males of 4-6 years and 40cm long become sexually mature earlier than females. They don’t die after spawning, and they can attempt reproduction over and over in own life. The mother 75 cm long breeds around 5,000 eggs at once. Over 10,000 eggs at 95 cm long.
The Japanese Huchen swim upstream to spawn. The female makes a redd on the riverbed of the transitional zone between the pool and the shallow. The redd is bigger than the redds made by the other kinds of trout and salmon. It is eliptic reaches 2-3 meters across in maijor diameter. The female breeds 5-6 times a day, and she often mates with deferent males one after another. Mostly the female marries with the male smaller than herself. When males fight over a female, the bigger will win.
You can investigate the age of the Japanese Huchen by the rings of his scales, but it’s difficult when the fish is old. Generally the fry grow up to 7 cm long in the next spring after the hatch. 13.4 cm by 2, 19.0 cm by 3, 24.5 cm by 4, 30.0 cm by 5, 35.4cm by 6. They can easily live over 15-20 years.
The egg is vivid orange-red. It is around 6 mm in diameter. The eyes appear after 21 days of the fertilization in the water of 8 ℃ temperature, and the fry hatch after 37-40 days. The fry have large yolks, although they have both the jews and teeth. The Juvenile 24.0-25.6 mm length shows the parr marks in its side, and the skull form between both eyes becomes flat when they grow up to 38.5 mm length. As 86.0 mm length, they are good-looking with fine black points above the body. The parr marks disappear when they grow 15 cm length. The Japanese Huchen have a habit of defending own territory after their young age.
The young Japanese Huchen under 10 cm long mainly eat larvas of the aquatic insects. As they grow up, they eat primarily fish. The great Japanese Huchen also prey frogs, snakes and mice.