name / Ito
Ito is listed as an Endangered Species in the Red List of the Japanese Ministry of Environment, and listed in the Red Data Book by Office of Hokkaido Prefecture. Soon the IUCN Salmon Specialist Group with assistance from Obirame Group will list Ito on the IUCN International Red Book of Endangered Species.
|Japanese Huchen ( Ito ) is one of the largest freshwater fish in Japan. However, the species is in serious threat of extinction. Especially OBIRAME, or, name of Ito of the lives in Shiribetsu Rriver, has been critically endangered since 1980's.|
Ito's native range in Japan only includes Hokkaido Island, the Japan's northernmost island. Yet even in Hokkaido the number of rivers with natural spawning Ito are decreasing rapidly due to the destruction of the river environment.
Ito fry emerge from their eggs in the headwaters of rivers. The juveniles mature in the middle section of the river and some even migrate down to the river mouth and sea as adults. In order to complete its natural migration, Ito need rivers without obstructions and barriers (dams for example).
The Shiribetsu River is the southernmost habitat of wild populations of Ito.
How big the fish is?
Old records tell us that a 2.1 meter Ito was caught in Tokachi River (E. Hokkaido) in the 1930s. In the Shiribetsu River, we have heard that an angler caught a "big one" measuring 1.53 meters. As a fry, Ito are very small. Because Ito are slow growing, it may take 5- 6 years for an Ito to reach 50 cm.
How long the fish lives?
Ito can reach the old age of 15 years. Male Ito achieve reproductive age at around 4 years, while females are ready to spawn by about 6 years. One of the special characteristics of the Ito is that they usually survive after spawning (unlike other salmonid species that die after spawning). Some individuals attempt to spawn on a yearly basis while others spawn every 2-3 years.
About the Siribetsu River population......
Obirame is the Ainu name for Ito. Older anglers living in the Shiribetsu River basin also use this name for Ito. Therefore, in reverence to the Ainu people and the older anglers who enjoy this river we use the name "Obirame".
One of the goals of the Obirame Restoration Group is to find evidence of natural Ito reproduction. Although we have been unable to locate any nests or fries, we have been able to find and capture several adults for our captive breeding program.