瀬戸内海におけるエイラクブカHemitriakis japonica(Mueller et Henle)の二度目の出現例と出現傾向及び食性

The Second Record, Tendency of Occurrence and Food Habit of Eiraku Shark Hemitriakis japanica (MÜLLER ET HENLE) in the Seto Inland Sea.

Kamura Satoru

Hashimoto Hiroaki

Gushima Kenji

生物生産学研究

Journal of the Faculty of Applied Biological Science, Hiroshima University

一般に東シナ海の海底に棲息するとされているエイラクブカ Hemitriakis japanica が1997～'99年の間に本邦瀬戸内海の愛媛県今治魚市場にて頻繁に陸揚げされた。これまで瀬戸内海での出現記録は、播磨灘で一例あるのみで、今回のこれらの記録は2例目となる。本種は6～11月に集中して出現し、採集個体数は雄29尾、雌17尾、雄:TL=440～993mm、雌:TL=424～773mmで、雄でのみTL900mm以上の大型個体が採集された。雌雄共に1～4歳と推測される未成熟個体がほとんどだった。それぞれの全長-体重の関係は雄:BW=9×10-6TL2.849r=0.980、雌:BW=5×10-5TL2.595r=0.967であった。食性に関して本種は横に長いアーチ状の口器と「噛みつき+切断型」と分類される歯列を用い、頭足類及び魚類を重要な餌生物として摂取していることが明らかとなった。

Eiraku Shark Homitriakis japanica, which inhabits commonly on the bottom of the East. China Sea, was often landed in Imabari Fish Market, Ehime Prefecture, the central Seto Inland Sea of Japan. This report is the second record that this species was caught in the Seto Inland Sea, following the first record (Yokogawa and Yamaguchi, 1997). The specimens of this species were caught concentrically between June and November for three years. 29 males and 17 females were collected. Total length was 440~993 mm in male and 424~773 mm in female, respectively, and the most of specimens were guessed to be 1-4 years old, and not sexual mature. The total length-weight relationships was BW = 9 X 10-6 TL2.849 r = 0.980 for male and BW = 5 X 10-5 TL2.595 r = 0.967 for female respectively, a tendency that male was a little heavier than female was showed. This species had laterally wide mouth like an arch and their teeth were classified "clutching+cutting type", and fed cephalopods and teleosts as important prey items with them.

エイラクブカ

Hemitriakis japanica

食性

瀬戸内海

全長-体重関係

Eiraku shark

food habit

the Seto Inland Sea

total length-weight relationship

Zoology [ 480 ]

jpn

広島大学生物生産学部

農林水産研究情報センター

[ISSN] 1341-691X

[NCID] AN10409040