In the light of the present situation that placement of artificial fish-reefs has been strongly promoted in order to develop inshore fisheries, we began to study three multi-component artificial fish-reefs in Kata Bay, Pacific coast of Central Japan, as a model of artificial fish-reefs, to clarify function and effect of them. As a fundamental study, in this article we made a general description of the study fish-reefs first, then dealt with encrusting organisms and fish communities.
The study fish-reefs were built in 23-35m depth, from 1973 to 1976, almost at the middle between two set-nets situated close to each other. Main aim of placement of the fish-reefs is to attract fish for the set-nets. Three multi-component artificial fish-reefs are each constructed of 785㎥ of quarry rocks, 124 concrete shelteres, and 259 units of tier shelters. The tier fish-reef is accompanied by some five wooden ships. Biological surveys were carried out six times from 1977, eleven months after completion of the fish-reefs, to 1980, through direct obsevations by using SCUBA. Besides automatic under-water cameras acting by interval-timer and under-water TV with remote-control were occasionally used to watch come-and-go of fish on the fish-reefs.
Communities of encrusting organisms are referable to a feather duster worms-moss animals complex. Most dominant species are Hydroides norvegica and caberea lata. Flora is very scarce as it is too deep. Though restricted to the most shallow, quarry rock fish-reef, only a brown alga, Ecklomiopsis radicola, has been found flourishing. 81 fish species representing 41 families and 64 genera were observed in all. Most frequently seen and important commercial fish are sardine, Sardinops melanosticta, anchovy, Engraulis japonicus, beackperch, Oplegnathus fasiatus, grunt, Parapres-tipoma trilineatum, and jack mackerel, Trachurus japonicus. Fish observed on the fish-reefs were classified on the basis of mode of life and relationship to the fish-reef into three categories under the names of visitor, transient and resident. Some discussions on the relationships between fishes belonging to respective categories and the fish-reef were made and ended with a conclusion that the height of the artificial fish-reef is one of the important factors yeiding sufficient reef-effects.
雑誌名
三重大学水産学部研究報告 = Bulletin of the Faculty of Fisheries, Mie University
Studies on the Artificial Fish-reefs in Kata Bay, Encrusting Organisms and Fish Community
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