Everything about Ayu totally explained
| species =
P. altivelis
| binomial =
Plecoglossus altivelis
| binomial_authority = (Temminck & Schlegel, 1846)
}}
The
ayu (アユ, 鮎) or
sweetfish,
Plecoglossus altivelis, is an
amphidromous fish, the only
species in the
genus Plecoglossus and in
family Plecoglossidae. It is a relative of the
smelts and is placed in the
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.
The name "sweetfish" is due to the sweetness of its flesh. In reference to its typical one-year life span, it's also known as
nen-gyo ("year-fish"). The ayu is
Gunma Prefecture's prefectural fish.
Systematics
The
Ryūkyū ayu (
Plecoglossus altivelis ryukyuensis) is a
subspecies of ayu,
endemic to the
Ryukyu Islands: it's much smaller, with a maximum
total length of only about 14 cm (5.5 in).
IUCN classifies the Ryūkyū ayu as
Endangered on the basis of declining and highly fluctuating population and limited and declining range and habitat, but cautions that the status is in need of reassessment.
The
mitochondrial control region, usually held to be
hypervariable and
evolving rapidly, is peculiar in the ayu. For reasons unknown, the Ryūkyū population's control region differs from that of others far less than for example
genes encoding for
proteins. A consequence of this fact is that control region
DNA sequences, commonly used in molecular
phylogenetics, provide unreliable data for the ayu. In addition, identification of ayu to
subspecies can't be accurately performed using control region sequence data.
Ecology and uses
An
omnivore, the ayu feeds on
algae,
crustaceans,
insects,
sponges, and
worms. They are also very territorial animals. 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.
Ayu is an edible fish, mostly consumed in
East Asia. Its flesh has a distinctive, sweet flavour with "melon and cucumber aromas". It is consequently highly prized as a food fish. The main methods for obtaining ayu are by means of
fly fishing, by using a
trap, and by fishing with a decoy which is known as
ayu-no-tomozuri in Japan. The decoy is a living ayu placed on a hook, which swims when immersed into water. It provokes the territorial behavior of other ayu, which assault the "intruder" and get caught. This method has been criticized for its cruelty towards the animal.
Japanese
anglers also catch it a traditional method,
cormorant fishing (鵜飼
ukai). On the
Nagara River where
Japanese Cormorants (
Phalacrocorax capillatus) are used by the fishermen, the fishing season draws visitors from all over the world. The Japanese Cormorants, known in Japanese as
umi-u (ウミウ, "sea-cormorant"), are domesticated birds trained for this purpose. The birds catch the ayu, store it in their
crop, and deliver it to the fishermen.
Ayu is also fished commercially in large numbers, and captive juveniles are raised in
aquaculture before being released into rivers for sport fishing.
Footnotes
Further Information
Get more info on 'Ayu'.
|
External Link Exchanges
Do you know how hard it is to get a link from a large encyclopaedia? Well we're different and will prove it. To get a link from us just add the following HTML to your site on a relevant page:
<a href="http://ayu.totallyexplained.com">Ayu Totally Explained</a>
Then simply click through this link from your web page. Our crawlers will verify your link, extract the title of your web page and instantly add a link back to it. If you like you can remove the words Totally Explained and embed the link in article text.
As long as your link remains in place, we'll keep our link to you right here. Please play fair - our crawlers are watching. Your site must be closely related to this one's topic. Any kind of spamming, dubious practises or removing the link will result in your link from us being dropped and, potentially, your whole site being banned. |
