|Scientific Name:||Acipenser mikadoi|
|Species Authority:||Hilgendorf, 1892|
|Taxonomic Notes:||The taxonomic status of the species has only recently been clarified. It was considered conspecific with North American Green Sturgeon (A. medirostris) (Shmigirilov 2007).|
|Red List Category & Criteria:||Critically Endangered A2cde ver 3.1|
|Reviewer(s):||Pourkazemi, M. & Smith, K.|
The Tumnin River is the only known persistent spawning river for Sakhalin Sturgeon (to 100 km upstream). The species population and habitat is declining due to illegal poaching during the migration run and pollution of habitat from agriculture, oil production and mining is causing a decline in habitat quality. The area of the species spawning grounds is estimated to be more than 10 km² (extent of occurrence (EOO) is over 100 km²). Over the past 45 years (estimated three generations) there has been a massive decline in wild mature individuals, suspected to be more than 80%. It was common in the fish markets of Japan in the 1950s and now only a few specimens are found per year.
|Range Description:||This species ascends small coastal rivers of the Russian Federation (Suchan (Partizanskaya), Adzemi, Koppi, Tumnin, Viakhtu, and Tym rivers) and Japan (Ishikari and Teshio rivers of Hokkaido). It is found at sea, throughout the Sea of Okhotsk, in the Sea of Japan as far east as the eastern shore of Hokkaido, Japan, along the Asian coast as far south as Wonsan, North Korea, and to the Bering Strait on the coast of the Kamchatka Peninsula (Shmigirilov et al. 2007).
It is currently only known to spawn persistently in the Tumnin River (not further than 100 km upstream from the estuary), where only a single spawning site is known. It has also rarely been found in the Koppi River. This population may be functionally dependent on the Tumnin River or simply ephemeral (Shmigirilov et al. 2007).
Native:Japan; Russian Federation
|FAO Marine Fishing Areas:||
Pacific – northwest
|Range Map:||Click here to open the map viewer and explore range.|
Although never abundant, the species was common in the 1950s in the market in Hokaido, Japan, but has been continually declining over the past century (Shmigirilov et al. 2007)
Current population estimates range from ten to thirty adults entering the Tumnin River for spawning annually. In 2005 only three specimens were caught and two specimens in 2008 - these were used for the establishment of aquaculture stocks.
|Habitat and Ecology:||
Sakhalin Sturgeon spawn in June-July in the Tumnin River and April and May (historically) in the rivers of Hokkaido (Shmigirilov et al. 2007).
Estuaries are thought to be the nursery grounds for the species. They are mainly benthic feeding and feed in higher salinity waters (than Amur and Kaluga which share range), where food resources are more abundant than in temperate coastal watersheds (Shmigirilov et al. 2007).
The species generation length is estimated to be 15 years, with first maturation around 8-10 years (based on similarity to A. medirostris).
|Use and Trade:||Wild sturgeon are caught for human consumption.|
Illegal poaching (during spawning migration) is greatly affecting the viability of the species in the Tunmin river and this population could vanish within the next 10-15 years (Shmigirilov et al. 2007).
Bycatch is a threat to the species as there is a lot of trawling off the coast. Pollution and the potential construction of dams is also a threat to the species.
More research is needed, particularly on the migration, feeding ecology, the productivity of natural reproduction and life history (Shmigirilov et al. 2007). Population monitoring is also required.
Considering the low abundance of this species, research should focus on investigating potential environmental limiting factors (especially estuarine conditions), determining survival rates of the age stages and fecundity (Shmigirilov et al. 2007).
Conservation aquaculture techniques have been developed since 1995.
Public education, applied management research, and experimental research are necessary to develop better plans for protecting these species from extinction.
International trade is restricted (CITES II, since 1998; CMS Appendix II). Commercially cultured in Japan, and there is a large stock in Sakhalin which has originated from Tumnin spawners.
|Citation:||Mugue, N. 2010. Acipenser mikadoi. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 30 July 2015.|
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