Oikawa - Oikawa

Japanese: オイカワ - おいかわ

A freshwater fish belonging to the order Cypriniformes and family Cyprinidae of the class Osteichthyes. It has local names such as hae, sirahae, hasu, yamabe, asaji, jinken, and shouhachi. It was distributed in the Shinano River on the Sea of Japan side, and in parts of Honshu, Kyushu, and Shikoku west of the Tone River on the Pacific side, but was introduced to various places mixed with the released seedlings of sweetfish, and is now distributed throughout Japan except Hokkaido and Okinawa. It is also distributed in the Korean Peninsula, Taiwan, and China. It is a small fish about 15 cm in length, with a downward curved lateral line and no whiskers. It is similar to the chum salmon, but the color spots on its side are clearly different. It often lives in shallow, open water such as the coasts of lakes and flats in the middle and lower reaches of rivers, where it mainly feeds on attached algae and leaves small feeding marks on the surface of stones. It also eats aquatic and terrestrial insects and planktonic organisms. They lay eggs in the shallows of rivers and on the gravel bottoms of lakes from May to August. During this time, males are colored in deep red, blue, and green, so they are also called Joro-buna (buffalo carp) or Aka-hae (red fly).

While artificial changes to the river environment, such as river improvement, water pollution, and construction of dams and weirs, tend to reduce the population of other fish species, they do not have a significant negative effect on this species, and in fact often promote its reproduction. Therefore, it is generally misplaced to be happy about the increase in the population of this species. It is often eaten during the cold season from late autumn to early spring.

[Nobuhiko Mizuno]

fishing

Clear streams can be fished throughout the year, while lakes and marshes can be fished from early summer to summer. In the Kanto region, especially around Tokyo, the fishing season is spring and autumn, while in the Kansai region, the fishing season is during the coldest months of the year. From around May, when the water temperature rises, to early autumn, drift fishing is done with a single ball float and bait made from stonefly larvae called Choromushi or Hunchbacks that live under stones near the riverbank. This is called Fukase fishing. In the coldest months of the year, fishing is done in areas with a little more depth, so a standing float is used while casting in a mixture of roasted rice bran, sake lees, and pupa powder as bait. Good bait for this time of year is sashi (sabamushi) or kneaded bait. In western Japan, red-dyed spaghetti is also used.

[Toshio Matsuda]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

硬骨魚綱コイ目コイ科に属する淡水魚。ハエ、シラハエ、ハス、ヤマベ、アサジ、ジンケン、ショウハチなどの地方名がある。日本海側は信濃(しなの)川、太平洋側は利根(とね)川以西の本州と九州、四国の一部に分布していたが、アユの放流種苗に混じって各地に移入され、現在では北海道と沖縄を除く日本全国に広がっている。朝鮮半島、台湾、中国にも分布する。全長15センチメートルぐらいの小魚で、側線が下方に湾曲し、口ひげはない。カワムツに似ているが、体側の色斑(しきはん)が明瞭(めいりょう)に異なる。湖の沿岸部や川の中下流の平瀬など、浅く開けた水面に多く生息し、付着藻類を主食とし、石表面に小さい食(は)み跡を残す。水生、陸生の昆虫や浮遊生物も摂食する。5～8月に川の平瀬や湖岸部の砂礫(されき)底に産卵する。この時期の雄は、体色が赤、青、緑に濃く彩られるので、ジョロウブナ、アカハエなどともよばれる。

　河川改修、水質汚濁、ダムや堰堤(えんてい)の建設など河川環境の人為的改変は、ほかの魚種を減少させる傾向があるのに対して、本種には大きな悪影響を与えず、逆に繁殖を促進することが多い。したがって、本種の増加を喜ぶことは一般に的はずれといえる。晩秋から早春の寒い季節によく食用とされる。

［水野信彦］

釣り

清流は四季を通じ、湖沼は初夏から夏にかけてが釣り期である。関東地方、とくに東京周辺では春と秋で、関西地方では寒中を釣り期とする。水温の上昇する5月ごろから初秋までは、玉ウキ1個をつけ、川の岸寄りの石下にいるチョロムシとか瀬虫(せむし)とよばれるカワゲラ類の幼虫を餌(えさ)にして流し釣りをする。これがフカセ釣りである。寒中はやや水深のある場所を釣るので炒糠(いりぬか)、酒粕(さけかす)、蛹粉(さなぎこ)などを混合した寄せ餌(え)を投入しながら、立ちウキなどで釣る。この時期の餌はサシ（サバムシ）や練り餌がよい。なお西日本ではスパゲッティの紅染めなども用いる。

［松田年雄］

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