parr mark

Japanese: parr mark（英語表記）parrmark

...In Wakayama it is called Kirikuchi, in the Chugoku Mountains it is called Gogi, and in Fukui it is called Imouo, and each of these is considered to be a separate lineage of the same species, with independent distribution. It grows to about 30cm in length, with oval parr marks on the sides of the body, small light grey circular spots, and even smaller vermilion spots below the lateral line. These spots vary from individual to individual, and there is a theory that each is a different species (Ezo-iwana, Nikko-iwana, Yamato-iwana), but since there is a tendency for the variation from north to south, there is also a theory that it is a regional variation within the same species, and it is not consistent. ...

From [Salmon]

...In the river, the young fish grow by eating the larvae of aquatic insects such as chironomids and water fleas. At this stage, the young fish have oval patterns called parr marks on their sides. They descend to the sea on the melting snow in April and May, but remain on the coast for a while, and disappear offshore when the water temperature reaches about 15°C.

*Some of the terminology explanations that mention "parr mark" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…和歌山ではキリクチ，中国山地ではゴギ，福井ではイモウオと呼ばれ，これらはそれぞれ独立した分布をする同一種内の別系群と考えられる。体長は30cmほどになり，体側に小判形のパー･マークparr markという斑紋をもち，また，小さな淡灰色の円点があり，側線より下にはさらに小さな朱点が混在する。これらの斑点には個体によって変異が認められ，それぞれが異なった種類(エゾイワナ，ニッコウイワナ，ヤマトイワナ)とする説があるが，変異に北から南への傾向性が存在するため同一種内の地方的変異とする説があり一定しない。…