On the Fish Gathering Effect of the Artificial Reefs ascertained by the Diving Observation III : At the Off Sea of Taniyama, Kagoshima City

Diving observations were carried out twice in March and in May, 1979, concerning the following artificial reefs which had been set in the sea front off Taniyama beach in Kagoshima City: concrete blocks, dilapidated bus; sunken boat, earthen pipes; withered trees. The results obtained are as in the following: 1) The artificial reef which was ascertained to be most effective for gathering fishes was the reef consisting of a sort of combination of the concrete blocks and the dilapidated bus, and during the period from March to June Chrysophrys major and Therapon oxyrhynchus were observed to have been gathered much. 2) In case of the dilapidated bus, due to the erosive decay of the iron board, most of the ceiling was made to be lost away; however, this turned the bus into a sort of box typed artificial reef, which was in possession of somewhat enhanced fishing gathering effect. 3) Such small sized fish as Apogon emilineatus was apt to be allured to the withered tree reefs. Accordingly, it was assumed that the realization of a combination of these withered tree reefs with other artificial reefs which were alluring to the large-sized fishes would give us a heightened effect in fish gathering.鹿児島市谷山沖合海域に設置してあるコンクリートブロック,古バス,廃船,土管,樹木の各魚礁を昭和 54 年 3 月と 5 月に潜水観察した結果,次のような知見を得た。 1) 最も魚群の蝟集効果の優れた魚礁は,コンクリートブロック魚礁とバス魚礁を組み合せた形式のもので,マダイ,イサキの大型魚が蝟集するといわれている。今回はネンブツダイとイセエビ等を観察した。 2) バス魚礁は設置後 10 年を経過すると,鉄板が腐蝕して屋根の大部分を消失する。しかしそのため,箱型の魚礁となり,魚群の蝟集効果は増加する。 3) 樹木魚礁にはネンブツダイ等の小型魚が多く蝟集する傾向がある。従って他の魚礁と組合せることにより,大型魚の来遊を招き,生産効果をあげることが出来るようである