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 VII : マクラザキシ オキアイ カイイキ ノ バアイ

Concerning the concrete block reefs and the tire reefs set at the off sea of Makurazaki City, diving observations were carried out; with the following results obtained. (1) The formations of both of the reefs were ascertained to be two hillock shaped, with the similar side figures shown; as to the figures of the central parts it may be said that in case of the concrete blocks it was of a saddle shape, and in case of the tire blocks, of a concaved dish shape. (2) On and along the concaved parts of the both reefs, dense gatherings of the big shaped migrating as well as stationary fishes were noted; especially, Trachrus japonicus, Parapristipoma trilineatum, Apogon semilineatus and Plectorhynchus pictus were numerous. (3) Almost all the fish schools allured towards the concrete blocks were bigsized ones; while in case of the tire reefs, small sized immature fishes were numerous, the reason why the sizes of the gathering fishes were full of variety was assumed to be due to the difference in the structural features of the respective reefs; in other words, in the former cases the open spaces are big enough to let the big sized fishes be through and in the latter cases those are too small to let them be through, only letting the small ones be in.枕崎市沖合に設置されているコンクリートブロック魚礁とタイヤ魚礁について潜水観察を実施した結果,次のような知見を得た。 (1) 両魚礁の形態は,側面形状の酷以した2山型であるが,中央部分の形状が,コンクリートブロック魚礁では鞍型,タイヤ魚礁では皿型の凹みをなしている。 (2) 両魚礁のこの凹みの部分には,回遊性,定座性の大型魚および小型魚が密群をつくる。特にイサキ,ネンブツダイ,アジ,コショウダイが多い。 (3) コンクリートブロック魚礁に蝟集している魚群はほとんど成魚が多い。特にイサキ・マダイは顕著である。このように蝟集魚の体型に差があるのは,魚礁の個体の構造が異なるためであろう