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Plecoglossus altivelis (Temminck & Schlegel, 1846)

Ayu sweetfish
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Plecoglossus altivelis   AquaMaps   Data sources: GBIF OBIS
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Image of Plecoglossus altivelis (Ayu sweetfish)
Plecoglossus altivelis
Picture by Islam, Md. S.


Japan country information

Common names: Ayu, Koayu, Ryukyu-ayu
Occurrence: native
Salinity: freshwater
Abundance: abundant (always seen in some numbers) | Ref: Pastene, L.A., K. Numachi and K. Tsukamoto, 1991
Importance: highly commercial | Ref:
Aquaculture: commercial | Ref:
Regulations: | Ref:
Uses: gamefish: yes;
Comments: Occurs in western Hokkaido southward (Ref. 559, 11230). Found in Hokkaido's Ishikari river and the southern tributaries and river mouths (Ref. 12218); Nansei-shoto (Ref. 34989); Futatsukawa Creek, Fukuoka Prefecture (Ref. 37350); and Himi region from a habitat study conducted in Toyama Bay (Ref. 58909). Highly esteemed food and game fish. Cultured throughout western Japan in sea cages. Recorded as having been or being farmed in rice fields (Ref. 119549). Category in the 2005 Red Data Book of Shiga Prefecture: important distribution (Ref. 79825). Also Ref. 45563, 96271.
National Checklist:
Country Information: https://www.cia.gov/library/publications/resources/the-world-factbook/geos/ja.html
National Fisheries Authority: http://www.maff.go.jp/eindex.html
Occurrences: Occurrences Point map
Main Ref: Masuda, H., K. Amaoka, C. Araga, T. Uyeno and T. Yoshino, 1984
National Database:

Common names from other countries

Classification / Names Nombres comunes | Sinónimos | Catalog of Fishes(Género, Especie) | ITIS | CoL | WoRMS | Cloffa

> Osmeriformes (Freshwater smelts) > Plecoglossidae (Ayu fish)
Etymology: Plecoglossus: Greek, pleko, plekein = to fold + Greek, glossa = tongue (Ref. 45335).
  More on authors: Temminck & Schlegel.

Issue
All subspecies of Plecoglossus altivelis (Temminck & Schlegel, 1846) are synonymised under the species in Eschmeyer (CofF ver. Jul. 2010: Ref. 84883). Please send references, or more studies are needed.

Environment: milieu / climate zone / depth range / distribution range Ecología

marino; agua dulce; salobre demersal; anfidromo (Ref. 51243); rango de profundidad 10 - ? m.   Subtropical; 44°N - 23°N

Distribución Países | Áreas FAO | Ecosistemas | Ocurrencias, apariciones | Point map | Introducciones | Faunafri

Northwest Pacific: western Hokkaido in Japan southward to the Korean Peninsula, Taiwan and China.

Length at first maturity / Tamaño / Peso / Age

Maturity: Lm 27.5, range 30 - 40 cm
Max length : 70.0 cm TL macho / no sexado; (Ref. 12218); common length : 15.0 cm SL macho / no sexado; (Ref. 35840); edad máxima reportada: 3.00 años (Ref. 12218)

Short description Claves de identificación | Morfología | Morfometría

Espinas dorsales (total) : 0; Radios blandos dorsales (total) : 10 - 11; Radios blandos anales: 14 - 15; Vértebra: 60 - 63. Pyloric caeca 350-400.

Biología     Glosario (por ej. epibenthic)

Typical amphidromous fish; appears in near shore from late autumn to spring (Ref. 11230). Found in lakes and rivers, preferring clean river water and can be found the entire river long, from the head to the mouth (Ref. 12218). Ascends the river during March when the temperature is around 10°C (Ref. 12218). Adults spawn in the spring, in the lower reaches of rivers. After spawning, some adults die while others return to the sea. Larvae enter the sea immediately after hatching and remain there during winter, feeding on plankton. In springtime, the young (5-7 cm TL) move upstream to the middle reaches of rivers to feed on algae. Fish (about 6-9 cm) start schooling at the river mouth and are insectivores and eat algae off small pebbles (Ref. 12218); this is assisted by small leaf-like teeth which are loosely attached to the jaw with two ligaments (Ref. 45181). Those that are ready to spawn (about 20 cm TL) move downstream to the lower reaches of the river. Spawning adults from the sea migrate upstream to the lower reaches as well. Some fish spawn two or three years in succession, others only once (Ref. 9987 & 559). River forms live usually only one year whereas lake forms can live two or three years (Ref. 12218). Reaches maturity at 30-40 cm (Ref. 12218). Highly esteemed food fish. Marketed fresh and consumed fresh, fried and broiled (Ref. 9987).

Life cycle and mating behavior Maturities | Reproducción | Spawnings | Egg(s) | Fecundities | Larva

During spawning some fish go up the river and some fish spawn on the river shoreline above pebbles. Spawns at night and excavates a 10cm (diameter or depth?) pit. Eggs are around 1 mm in size and adhere to the sand or pebbles for 14 to 20 days before hatching. This fish is semelparous and releases eggs many times over a short period each time releasing ~10,000 eggs. Sometimes females that want to spawn but cannot, save their strength, and go to a deep stagnant pool. These females wait until spring before going up the river with young fish. After hatching, the larvae are 6 mm and flow with the water current eating plankton. Juvenile fish will come again to the river in spring. These live in schools. When schools of Plecoglossus altivelis return to their river they guard their territory and eat food (Ref. 12218). Reproductive mode varies between semelparity and iteroparity. Large females spawn once, while smaller females spawn twice during a two-week interval (Ref. 76896).

Main reference Upload your references | Referencias | Coordinador | Colaboradores

Masuda, H., K. Amaoka, C. Araga, T. Uyeno and T. Yoshino, 1984. The fishes of the Japanese Archipelago. Vol. 1. Tokai University Press, Tokyo, Japan. 437 p. (text). (Ref. 559)

IUCN Red List Status (Ref. 130435)

  Data deficient (DD) ; Date assessed: 03 September 2010

CITES (Ref. 128078)

Not Evaluated

CMS (Ref. 116361)

Not Evaluated

Threat to humans

  Harmless




Human uses

Pesquerías: muy comercial; Acuicultura: comercial; pesca deportiva: si
FAO(Aquaculture systems: producción; pesquerías: producción, species profile; publication : search) | FishSource | Sea Around Us

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Ecology
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Length-weight rel.
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Estimates based on models

Preferred temperature (Ref. 115969): 13 - 22.6, mean 19.7 (based on 42 cells).
Phylogenetic diversity index (Ref. 82804):  PD50 = 1.5000   [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00427 (0.00165 - 0.01101), b=3.07 (2.84 - 3.30), in cm Total Length, based on LWR estimates for this (Sub)family-body shape (Ref. 93245).
Nivel trófico (Ref. 69278):  2.8   ±0.16 se; based on food items.
Resiliencia (Ref. 120179):  Alto, población duplicada en un tiempo mínimo inferior a 15 meses (tm=1; tmax=3; Fec=50,000-100,000).
Fishing Vulnerability (Ref. 59153):  Moderate to high vulnerability (48 of 100).
Price category (Ref. 80766):   Unknown.