Ayu
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| Plecoglossus altivelis (Temminck & Schlegel, 1846) |
This is an article about the fish species 'ayu'. For other uses see Ayu (disambiguation).
The ayu or sweetfish, Plecoglossus altivelis, is an amphidromous fish, the only species in the genus Plecoglossus Temminck & Schlegel, 1846, and in family Plecoglossidae (order Osmeriformes). Native to the Palearctic ecozone, it occurs in rivers, lakes, and coastal waters of western Hokkaidō in Japan southward to the Korean Peninsula, China, and Taiwan.
Omnivorous, the ayu feeds on algae, crustaceans, insects, sponges, and worms. The adults ascend from coastal waters into the lower reaches of rivers to spawn in the spring. The larvae descend to the sea immediately on hatching and winter there before returning to fresh water again in the spring. Most but not all individuals die after their first spawning.
The flesh of the ayu has a distinctive, sweet flavour with "melon and cucumber aromas" (Gadsby). It is consequently highly prized as a food fish. Japanese anglers catch it with live lures as well as by a traditional method whereby captive cormorants catch the ayu and regurgitate the fish for human consumption (Akimichi). It is also fished commercially in large numbers, and captive juveniles are raised in aquaculture before being released into rivers for sport fishing.
Plecoglossus altivelis is also known as the sweetfish (for the sweetness of its flesh) or, in reference to its typical one-year life span, nen-gyo (year-fish). The ayu is Gunma Prefecture's prefectural fish.
[edit] Subspecies
The Ryūkyū ayu-fish (Plecoglossus altivelis ryukyuensis), is a subspecies of ayu, endemic to the Ryūkyū Islands, which reaches a maximum total length of only about 14 cm (5.5 in). IUCN classifies the Ryūkyū ayu-fish as Endangered on the basis of declining and highly fluctuating population and limited and declining range and habitat. They are also very territorial animals.
[edit] References
- Akimichi, Tomoya. "Queen of Freshwater Streams". Kikkoman Soy Sauce Food Forum. Accessed on 21 December 2004.
- Gadsby, Patricia. "The Chemistry of Fish". Discover, November 2004, 50–57.
- "Plecoglossidae". FishBase. Ed. Ranier Froese and Daniel Pauly. October 2004 version. N.p.: FishBase, 2004.
- "Plecoglossus". FishBase. Ed. Ranier Froese and Daniel Pauly. October 2004 version. N.p.: FishBase, 2004.
- "Plecoglossus altivelis altivelis". FishBase. Ed. Ranier Froese and Daniel Pauly. October 2004 version. N.p.: FishBase, 2004.
- "Plecoglossus altivelis ryukyuensis". FishBase. Ed. Ranier Froese and Daniel Pauly. October 2004 version. N.p.: FishBase, 2004.
- Plecoglossus altivelis (TSN 162027). Integrated Taxonomic Information System. Accessed on 20 December 2004.
- World Conservation Monitoring Centre. "Plecoglossus altivelis ssp. ryukyuensis" (ID 17595). 2004 IUCN Red List of Threatened Species. N.p.: IUCN, 2004.
