センスイ カンサツ ニヨル ジンコウ ギョショウ ノ ジッタイ ニツイテ IV : シブシワン ビロウジマ セイホウ カイイキ ノ バアイ

Three kinds of the artificial concrete block reefs which were different both in the lapse of time passed after they were submerged and in their sizes, respectively had been set at the off sea in the west of the Biro island in the Shibushi bay. During the period from December, 1978 to August, 1979, concerning these artificial reefs diving observations were carried out 8 times. The results obtained were as in the following: 1) It was accertained that the longer was the lapse of time passed after the setting the artificial reefs the figher were the fish gathering effects of those reefs. 2) The older the artificial reefs the higher was their alluringness to such a sort of fish as Chrysophrys major. The result of the catchability-test by gill net ascertained that 3 individual fish were caught per 10 m^<2> bottom area of the artificial reef. 3) The artificial reefs were supplied with a few kinds of device and attaching apparatus, and the catchabilities of the respective cases were compared; and in Apagon semll meatus, the following were ascertained; namely, in the case when four stanchions were set up right upon the surface of the artificial reef, the gathering section was spotted around those stanchions; and in the case when the surface lid of the artificial reef body which was turned into a box typed one through the loss of the surface lid.志布志湾の枇榔島西方海域に設置してある人工魚礁は設置後の経過年数と寸法が異なる 3 種のコンクリートブロック魚礁よりなる。これらの魚礁を,昭和 53 年 12 月より 54 年 8 月にかけて計 7 回の潜水観察を行なった。その結果, 1) 魚礁の蝟集効果は,魚礁の設置後の経過年数の古い程大である。また古い魚礁上に新しい魚礁を重ねて設置すれば,蝟集効果は更に大となる。 2) チダイは古い魚礁程多く蝟集する傾向がある。最も古い魚礁において,刺網による漁獲試験を行なった結果,魚礁底面積 10㎡ つき 3 尾の漁獲を得た。 3) 種々の付加物を有する魚礁でネンブツダイを観察した結果,陰の部分,礁上の突起物の周辺および箱型のくぼみの上部に密群を形成する現象がみられた。 4) 埋没の速さは 13~14cm/年であるが,この値は鹿児島県吹上浜沖の場合よりやや小さい値である