| Sakhalin taimen | |
|---|---|
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Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Salmoniformes |
| Family: | Salmonidae |
| Subfamily: | Salmoninae |
| Genus: | Parahucho Vladykov, 1963 |
| Species: | P. perryi |
| Binomial name | |
| Parahucho perryi (Brevoort, 1856) | |
| Synonyms[2] | |
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TheSakhalin taimen (Parahucho perryi,syn.Hucho perryi), also known as theJapanese huchen orstringfish (Japanese:伊富/イトウ,romanized: itō), is a large species ofsalmonidfreshwater fish inNortheast Asia, found in the lakes and large rivers ofPrimorsky,Khabarovsk,Sakhalin andKuril Islands ofFar Eastern Russia, as well asHokkaido ofJapan. Although often placed in the genusHucho,molecular phylogenetic and other evidence has shown that it belongs in its ownmonotypic genusParahucho.[3][4][5][6]
The population has been in general decline for a century at least, with contributory factors including degradation of the environment by logging,oil exploration and change of land use to agriculture. The fish is caught bycommercial fishing asbycatch, byrecreationalanglers and illegally bypoaching, and present populations are estimated to be less than 5% of their historic levels. TheInternational Union for Conservation of Nature has rated the fish as beingcritically endangered.[1]
The earliest known fossils of the genus are from the mid-lateMiocene-agedAgnevo Formation ofSakhalin Island.[7]
Parahucho perryi is one of largest, most ancient salmon species and primarily inhabits the lower to middle reaches of lakes and rivers. Fish over 30 cm (1 ft) long are almost exclusivelypiscivores, while the young feed mostly on aquatic insects. Females typically lay between 2,000 and 10,000 eggs in the spring on the sandy or gravelly river bottom.[8] The average specimens caught have weighed around 5 kg (11 lb).[1] The largest fish caught was recorded at 15 kg (33 lb 1 oz) (IGFA world record).[9] According to an unverified record from Japan, a fish with length of 2.1 m (6.9 ft) was captured in 1937 from theTokachi River,Hokkaidō.[citation needed]
Parahucho perryi are found in the Northwest Pacific:Sakhalin Island (Russia), the Island ofHokkaidō (Japan), and parts of the far eastern Russian mainland. Some populations spend all their lives in freshwater while others areanadromous. The fish take about eight years to mature and can spawn several times during their lifetime which is estimated to be about fourteen years.[1]
The global population of the species has dwindled in recent years for a variety of reasons. The loss of more than 50% of their original habitat due to agriculture, urbanization, and more recently, oil and gas development, is a major factor. Other considerable pressures includebycatch in the commercial salmonfisheries of Russia and Japan, as well asillegal fishing practices in Russia. The fish are also prized as trophies by Japanese recreational anglers.[10]
In Japan, this species is bred for game-fishing at managed fishing sites, and raised fish are available for purchase. However, the species remains critically endangered.
Since 2006, theIUCN has listedParahucho perryi ascritically endangered based on the assessment completed by the Salmonid Specialist Group. This designation represents the highest potential risk of global extinction to the species. The assessment revealed that the range-wide population has dropped in size to less than 5% of historic levels.[1][10]
