日本海南西海域におけるヒメジの底生生活期について

Abstract

The purpose of the present paper is to study the benthic life of Upeneus bensasi in the south-western Japan Sea. A total of 5474 samples were collected by otter trawl. The results obtained through this investigation are summarised as follows. 1. Upeneus bensasi settle in the bottom during July to October from 35mm to 60mm in total length. 2. Young fish which settled in the bottom were observed at the depth of 20-80m, and there is a difference in the size of fish. That is to say, fish in the deep are larger than those in the shallow. 3. The habitat in benthic life is from 20m to 120m in depth, and the number of fish decrease according to depth. 4. The conditions of the habitat varied seasonally with the size of fishes, and it is possible to classify them into the summer type (from July to October) and the winter one (from December to June). 5. Spawning occurs through a long period from May to September, but there is a distinct peak season from June to July. Both males and females of this fish attain sexual maturity at about 90mm in total length. 6. The relationship between the number of months (t) and the total length (Lmm), total length and body weight (Wg) is estimated as follows. Lt=245.7(1-e-0.034(t+5.420)) Male: W=3.97×10-6×L3.21 (r=0.989) Female: W=3.46×10-6×L3.24 (r=0.997)