A case of infestation by Limnotrachelobdella okae (Hirudinida: Piscicolidae) on Japanese Amberjack Seriola quinqueradiata cultured in Kyushu, Japan

2001年1月に大分県津久見市四浦地先の津久見湾で養殖されていたブリSeriola quinqueradiataの体表にヒダビルLimonotrachelobdella okaeの寄生を認めた。1984～1986年と1990～2007年の21年間に実施された大分県沿岸の海産魚の魚病診断で14,000尾以上のブリが検査されたが，本例が唯一のヒダビル寄生であった。また，寄生を受けていたブリは2000年12月に瀬戸内海中央部にある養魚場から搬入されたものであった。これらのことから，ヒダビルはブリの移動に伴って津久見湾に持ち込まれたと推測された。

Two leeches, identified as Limnotrachelobdella okae (Moore, 1924), were found attached to the skin of a Japanese amberjack Seriola quinqueradiata Temminck and Schlegel, 1845 (Perciformes: Carangidae) cultured in Tsukumi Bay, the northwestern Bungo Channel, off Youra, Tsukumi, Oita Prefecture, Japan in January 2001. Although a survey of fish diseases was conducted for 21 years from 1984-1986 and from 1990-2007 in the coastal seawaters of Oita Prefecture, this finding was the first and only case of leech infestation of marine fishes cultured in the region. Since the infested fish was transported from a fish farm in the central Seto Inland Sea in December 2000, it is highly likely that the leeches found were introduced to the culture site in Tsukumi Bay together with the transported fish.