Journal of the Faculty of Fisheries and Animal Husbandry, Hiroshima University Volume 7 Issue 1
1967-07-31 発行

走島の漁業 : Ⅰ 桝網の漁獲量よりみたウマヅラハギNavodon modestus (GÜNTHER) の漁況について

Fisheries in Hashiri-shima : I. On the catch of navodon modestus (GUNTHER) by masu-ami in Hashiri-shima
Murakami, Yutaka
Kakuda, Shunpei
The file-fish, Navodon modes/us (GÜNTHER) are caught by the masu-ami, a kind of pound net, which are operated along the coast of islands in the central part of the Inland Sea of Japan. Catching data of this fish in the areas of Hashiri-shima, Uji-shima and Hakama-shima during the seven years period (1960-1966) were collected from about one hundred nets, and analysed.

1) Fishing of N. modestus are operated during the three months from April to June in this area and the most abundant catches are seen in May. About 95% of the catch is trapped by the masu-ami and about 5% is caught by the gill nets.

2) The annual catch of N. modestus shows considerably sharp fluctuation. The maximal catch during the seven years period is 40 metric tons in 1962, and the minimum is 3 metric tons in 1966. The fluctuations in the daily catch are also seen clearly.

3) The stations of the abundant nets and those of the poor ones in the catch are fixed. Generally, the catches are abundant in near shore nets around the islands, and poor in off-shore nets setting southwestern area of Hashiri-shima and Uji-shima. The beginning, the peak and the end in fishing are the same among them. Two patterns of the seasonal variations of near shore nets and off-shore nets, obtained from smoothing by the five-place moving averages of the catch, show about the same fluctuations.

4) It is noticed that the seasonal variation patterns of the catch by the nets are the two types. The one is the unimodal distribution and the other is the bimodal. It is considered that the difference of the patterns may be dependant on the environmental conditions of the fishing ground or the migrational and spawnig behavior of the fish.