Recovery of aquatic animals in Dokai Bay, northern Kyushu, Japan

Abstract

Dokai Bay had been called a treasury area to catch Kuruma prawn; the catch from the bay reached a maximum in 1928. Aquatic animals, however, had been damaged by the untreated waste waters from Kitakyushu's heavy and chemical industrial area around the bay. The fishermen of Dokai Bay hadn't caught any fish since 1943, and from 1951 they were obliged to abandon their fishing rights of the inner and the middle parts of the bay. Such crushing damage from water polution atarted earlier than in other bays in Japan. Since then, due to the success to decrease the inflow of waste waters, the water quality of the bay was improved and commercial fishing of Kuruma prawn started again in 1983. Since 1988, the presence of aquatic animals has been investigated with gill nets and a small trawling net. One hundred and fifteen species of aquatic animals: 65 species of fish, 37 species of Arthropoda, 12 species of Mollusca, and 1 species of Echinodermata were collected in there investigations. Almost all of them were coastal-temperate species, and some of them were the same species as those reported in the previous period. The species collected in abundance were: Kuruma prawn, Hardback shrimp, Mantis shrimp, Common goby, Streaked goby, Black porgy, and Gizzard shad. Aquatic animals collected were aboundant except in summer at the inner part of the bay where no biota zone had been found. Several species which had disappeared or were on the verge of extinction in 1933 were caught this time.