瀬戸内海大崎上島沿岸域より採集された熱帯・暖海性魚類ソウシハギAluterus scriptus(カワハギ科 Monacanthidae) : 来遊背景の一考察 <短報>

ソウシハギは, 熱帯・暖海域に広く生息する大型のカワハギ科魚類である。2008年7月31日に, 瀬戸内海安芸灘の広島県大崎上島町木臼島沖合において本種の幼魚1個体(全長19.7cm)を発見・採集した。本種の幼魚は流れ藻に随伴し海流とともに移動すること, 過去にも瀬戸内海伊予灘での採集記録があることから, 黒潮の分流に乗って豊後水道を経由して流入してきたものと考えられた。瀬戸内海安芸灘の冬季水温環境は本種の越冬が不可能なレベルにあり, 死滅回遊として偶発的に出現したものと考えられる。

The scrawled filefish Aluterus scriptus (Osbeck) is widely distributed in the world's tropical/warm-temperate waters. We collected a juvenile (19.7cmTL) of A. scriptus with a hand net off Osaki-Kamijima Island in the Seto Inland Sea on July 31, 2008. Because juveniles of A. scriptus are known to be associated with drifting seaweed, and have already been recorded at Iyo Nada in the Seto Inland Sea, this suggests that A. scriptus is passively introduced into the sea through the Bungo Channel by the Kuroshio Current. Considering the lowest water temperature in the sea is ca. 10°C in winter, it appears impossible that such a tropical/warm-temperate fish could overwinter here. It is likely that A. scriptus was in the sea as part of an abortive migration along with other tropical fish juveniles. Because a strong poison (palytoxin) is present in the internal organs of this fish, it is important that we should not eat this fish.