Japan country information

Common names: Ayu, Koayu, ??
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 from western Hokkaido southward (Ref. 559, 11230). Found in Hokkaido's Ishikari river and the southern tributaries and river mouths (Ref. 12218). Also found in Futatsukawa Creek, Fukuoka Prefecture (Ref. 37350). Found to occur in the 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. Category in the 2005 Red Data Book of Shiga Prefecture: important distribution (Ref. 79825). Also Ref. 45563.
National Checklist:
Country Information: httpss://www.cia.gov/library/publications/resources/the-world-factbook/geos/ja.html
National Fisheries Authority: https://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:

Classification / Names

Actinopterygii (ray-finned fishes) > Osmeriformes (Smelts) > Plecoglossidae (Ayu fish)
Common names | Synonyms | Catalog of Fishes (gen., sp.) | ITIS | CoL

Common names from other countries

香鱼, سمك ليِّن أيو, Айю, ... more

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.

Main reference

Masuda, H., K. Amaoka, C. Araga, T. Uyeno and T. Yoshino. 1984. (Ref. 559)
References | Biblio | Coordinator | Collaborators

Size / Weight / Age

Max length : 70.0 cm TL male/unsexed; (Ref. 12218); common length : 15.0 cm SL male/unsexed; (Ref. 35840); max. reported age: 3 years (Ref. 12218)

Length at first maturity
L_m 20.0, range 30 - 40 cm

Environment

Marine; freshwater; brackish; demersal; amphidromous (Ref. 51243); depth range 10 - ? m

Climate / Range

Subtropical, preferred ?; 44°N - 23°N

Distribution

Northwest Pacific: western Hokkaido in Japan southward to the Korean Peninsula, Taiwan and China. A subspecies Plecoglossus altivelis ryukyuensis occurs in Nansei-shoto, Japan (Ref. 34989).
Countries | FAO areas | Ecosystems | Occurrences | Introductions

Short description

Dorsal spines (total): 0; Dorsal soft rays (total): 10-11; Anal soft rays: 14 - 15; Vertebrae: 60 - 63. Pyloric caeca 350-400.

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).

IUCN Red List Status (Ref. 115185)

Data deficient (DD)

Threat to humans

Harmless

Human uses

Fisheries: highly commercial; aquaculture: commercial; gamefish: yes

More information

Countries
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Ecosystems
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Ecology
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Food consumption
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Common names
Synonyms
Metabolism
Predators
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Reproduction
Maturity
Spawning
Fecundity
Eggs
Egg development

Age/Size
Growth
Length-weight
Length-length
Length-frequencies
Morphometrics
Morphology
Larvae
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References
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Collaborators
Pictures
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Summary page | Point data | Common names | Photos

Internet sources

Estimates of some properties based on models

Phylogenetic diversity index (Ref. 82805)
PD₅₀ = 1.5000 many relatives (e.g. carps) 0.5 - 2.0 few relatives (e.g. lungfishes)

Trophic Level (Ref. 69278)
2.8 ±0.16 se; Based on food items.

Resilience (Ref. 69278)
High, minimum population doubling time less than 15 months (tm=1; tmax=3; Fec=50,000-100,000)

Vulnerability (Ref. 59153)
Low to moderate vulnerability (30 of 100)

Price category (Ref. 80766)
Unknown

Plecoglossus altivelis altivelis (Temminck & Schlegel, 1846)