Kunimasu

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Kunimasu
Oncorhynchus kawamurae

Oncorhynchus kawamurae

Systematics
Overcohort : Clupeocephala
Cohort : Euteleosteomorpha
Order : Salmonid fish (Salmoniformes)
Family : Salmon fish (Salmonidae)
Genre : Pacific salmon ( Oncorhynchus )
Type : Kunimasu
Scientific name
Oncorhynchus kawamurae
Jordan & McGregor , 1925

The Kunimasu ( Oncorhynchus kawamurae , Japanese 国 鱒orク ニ マ ス Kunimasu ) is a species of fish from the genus of the Pacific salmon ( Oncorhynchus ) within the salmon fish family . The freshwater fish species disappeared in its original range, Lake Tazawa in Japan , due to the construction of a dam in 1945 and was considered extinct for a long time. It was not until 2010 that the Kunimasu was rediscovered in the Saiko .

Characteristics and way of life

Five month old Kunimasu in the Fuji Yusui no Sato Aquarium

The Kunimasu is a benthopelagic freshwater fish species that is a maximum of approx. 23 cm in size and occurs exclusively in the Saiko.It lives at a depth of around 38 to 180 m, but usually from 90 m depth, and in a temperature range of 4 ° C to 13 ° C. The fish species has a narrow torpedo-shaped body. Young animals have a slightly shimmering purple color, while adult individuals have a dark olive green color. Approx. 8 vertical, dark and oval spots run at the level of the sideline, especially in young animals. In addition, the tail fin is more indented in young animals. The fins of the Kunimasu only have soft rays and, as with almost all species of salmon fish, there is a small adipose fin . The species has 47–62 pyloric tubes and 37–43 gill pots .

In the wild, the Kunimasu feeds on mesopelagic and benthopelagic zooplankton , aquatic insects, freshwater shrimp , worms and other small fish. Like all salmon fish, the species is oviparous and spawns in fresh water over gravel or stony ground in a spawning pit formed by the female's violent tail movements. The kunimasu spawns year round, which sets it apart from other species of Pacific salmon.

Distribution history

Tazawa Lake - the original range
Saiko - today's distribution area near Mount Fuji-san

The Kunimasu was originally endemic to Lake Tazawa in Akita Prefecture , the deepest lake in Japan at 423.4 m . However, it has been extinct there since around 1948. The cause was the construction of a dam in 1945 as part of a program to increase electricity for the munitions industry during World War II . The water from Lake Tazawa was not sufficient for the hydropower plant , so that in addition , strongly acidic water was discharged into Lake Tazawa from the nearby Tama River , whose water source was an upstream thermal spring . As a result, Lake Tazawa quickly acidified, and the kunimasu and some other species disappeared.

Before that, however, fertilized eggs of the species were first introduced into lakes in Nagano , Yamanashi, and Toyama prefectures by fishermen around 1930 in order to establish additional populations for commercial fishing. In 1935 additional fish eggs were placed in the Fuji Lakes Saiko and Motosu in Yamanashi Prefecture and in Lake Biwa in Shiga Prefecture . In the decades that followed, however, no kunimasu were found in these lakes, leading to the assumption that the species became extinct with the disappearance of Lake Tazawa. In the second half of the 1990s, the Tazawako City Tourist Board wanted to promote the restoration of Lake Tazawa, which was once famous for its clear water, and the reintroduction of Kunimasu, which was once a culinary tourist attraction. A prize money of 5 million yen (the equivalent of 38,650 euros) was therefore announced for the discovery of Kunimasu. However, the action was unsuccessful and on July 28, 2008 several preserved specimens of the species were registered as a national cultural asset (登録 記念 物 tōroku kinen butsu ).

Rediscoverer "Sakana-kun"

It wasn't until 2010 that kunimasu were finally discovered in Saiko in Yamanashi Prefecture, and these are believed to be descendants of the eggs introduced in 1935. To the rediscovery of the Japanese television as "Sakana- was kun " ( "Mr. Fish") known ichthyologist and illustrator Masayuki Miyazawa (宮澤正之) played a key role. The background was the request of the biologist Tetsuji Nakabo from the University of Kyoto to him to make a drawing of the extinct Kunimasu. Miyazawa then had reference specimens of the related sockeye salmon sent from all over Japan and discovered a specimen from the Saiko that was similar to the Kunimasu. Nakabo's research group was finally able to confirm the fish as Kunimasu after a dissection and genetic analysis. This was officially announced by the media on December 14th, even before a scientific publication.

Endangerment status

An aquarium dedicated to Kunimasu on Lake Tazawa

The population in Saiko is estimated at around 10,000 fish. The lake is also known for its invasive species and breeding predators such as the sunfish Micropterus , the blue sunfish, and the European eel . In the original range of the Tazawa Lake there were no such natural enemies for the Kunimasu and it is assumed that the species nevertheless survived in the Saiko, as it lives in greater water depths.

The Kunimasu was in 2013 after the rediscovery in Saiko on the Red List of the IUCN and the national Red Data Book of Japan classified as "extinct in the wild", after he had been 2,007 previously classified as "extinct". The reason for the classification is that the fish were not introduced for conservation purposes (i.e. this introduction did not constitute a conservation or a benign introduction). Thus, the existing population in Saiko cannot formally be considered as a population in the wild for an assessment in the Red List. However, an aquarium in the city of Senboku is planning to reintroduce individuals from the Saiko to the original range in Lake Tazawa for protection purposes. If this reintroduction is successful, the population in Lake Tazawa can be assessed on the IUCN Red List. At the moment, however, the water quality of the lake is not yet sufficient to enable successful resettlement.

Systematics and etymology

Oncorhynchus kawamurae is a species of the Pacific salmon genus ( Oncorhynchus ) within the salmon fish family and was first described as such in 1925 by the American zoologists David Starr Jordan and Ernest Alexander McGregor . The species name kawamurae was a dedication to Tamiji Kawamura, a professor and freshwater biologist at the Imperial University of Kyoto , who provided specimens to describe the new species. The name of the genus is derived from the Greek words onkos (hook) and rhynchos (nose), and the common name is made up of the two Japanese words国 kuni (land) and鱒 masu (salmon trout). This illustrates the occurrence of the species exclusively in the interior of the country, whereas other species of the genus are partly distributed in the Pacific, including, for example, the Masu salmon around Japan .

The Kunimasu was at times viewed as a local subpopulation or subspecies of the sockeye salmon ( Oncorhynchus nerka ), which is also widespread in the Saiko and whose "black" populations in the Canadian Seton Lake and Anderson Lake are morphologically very similar to the Kunimasu . It was therefore considered unlikely that they differed greatly genetically. The Kunimasu, however, occurs in greater water depths, in which it also spawns, and this all year round, which distinguishes it both from other species of the genus. In addition, microsatellite DNA showed differences to the sympatric species Oncorhynchus nerka .

literature

  • N. Muto, K. Nakayama, T. Nakabo: Distinct genetic isolation between “Kunimasu” (Oncorhynchus kawamurae) and “Himemasu” (O. nerka) in Lake Saiko, Yamanashi Prefecture, Japan, inferred from microsatellite analysis. In: Ichthyological Research. Volume 60, 2013, pp. 188-194.
  • T. Nakabo, K. Nakayama, N. Muto et al .: Oncorhynchus kawamurae “Kunimasu,” a deepwater trout, discovered in Lake Saiko, 70 years after extinction in the original habitat, Lake Tazawa, Japan. Ichthyol Res. Volume 58, 2011, pp. 180-183. doi: 10.1007 / s10228-011-0204-8
  • Senboku City Municipal Office: Lake Tazawa Kunimasu Miraikan Senboku City. Senboku City Municipal Office, Senboku City 2017.
  • H. Sugiyama, A. Goto: Impressions of the sumposium "Kunimasu: its biological entity and conservation" held at the lecture open to the public of the Ichthyological Society of Japan in 2012. In: Japanese Journal of Ichthyology. Volume 59, 2012, pp. 182-184.

Web links

Commons : Kunimasu (Oncorhynchus kawamurae)  - Collection of images
Wikispecies : Oncorhynchus kawamurae  - Species directory

Individual evidence

  1. ↑ a b c d Oncorhynchus kawamurae. Fish lexicon, accessed March 23, 2021 .
  2. ↑ a b Oncorhynchus kawamurae Jordan & McGregor, 1925. FishBase, accessed on March 23, 2021 (English).
  3. ↑ a b c d e T. Nakabo, K. Nakayama, N. Muto et al .: Oncorhynchus kawamurae “Kunimasu,” a deepwater trout, discovered in Lake Saiko, 70 years after extinction in the original habitat, Lake Tazawa, Japan. Ichthyol Res. Volume 58, 2011, pp. 180-183. doi: 10.1007 / s10228-011-0204-8
  4. ↑ 国策 で 姿 を 消 し た 幻 の 魚 、 ク ニ マ ス. NHK, accessed January 29, 2021 (Japanese).
  5. ↑ a b c d 幻 の サ カ ナ 『ク ニ マ ス』 の 苦 労 が 尽 き な い 理由 次 な る 脅 威 は ウ ナ ギ？ Tsuri News, accessed January 29, 2021 (Japanese).
  6. ↑ 田 沢 湖 の ク ニ マ ス （標本）.国 指定 文化 財 等 デ ー タ ベ ー ス, accessed March 23, 2021 (Japanese).
  7. ↑ a b c Oncorhynchus kawamurae in the endangered Red List species the IUCN 2019. Posted by: Miyazaki, Y., Mukai, T. Nakajima, J., Takaku, K. & Taniguchi, Y., 2019. Accessed on 19th April 2021.
  8. ↑ Profile Sakana-kuns (Japanese)
  9. ↑ さ か な ク ン 絶滅 魚 発 見！ y-asakawa.com, accessed March 27, 2021 (Japanese).
  10. ↑ “絶滅” し た 幻 の ク ニ マ ス を 発 見. National Geographic, accessed January 29, 2021 (Japanese).
  11. ↑ Ministry of Environment: Brackish water and freshwater fish fourth Red List new and old comparison table. 2013. Red List Japan 2013 (PDF, 711 KB) .
  12. ↑ Senboku City Municipal Office: Lake Tazawa Kunimasu Miraikan Senboku City. Senboku City Municipal Office, Senboku City 2017.
  13. ↑ AR Morris, A. Caverly: Seton and Anderson Lakes kokanee assessment. British Columbia Conservation Foundation and Ministry of Water, Land and Air Protection, Kamloops, British Columbia 2004.
  14. ↑ AL Moreira, EB Taylor: The origin and genetic divergence of "black" kokanee, a novel reproductive ecotype of Oncorhynchus nerka. In: Canadian Journal of Fisheries and Aquatic Sciences. Volume 71, 2015, pp. 1584-1595.