原著論文
土佐湾におけるイサキ仔魚の分布生態
キーワード:
Parapristipoma trilineatum,
larva,
horizontal distribution,
morphology,
daily age,
spawning season,
early migration
2008 年 72 巻 2 号 p. 83-91
詳細
2008 年 72 巻 2 号 p. 83-91
The distribution of Parapristipoma trilineatum larvae was examined using a larva net (mesh aperture=0.5 mm, mouth diameter=1.3 m) and shirasu trawl (mesh size of bag-net=2 mm) collections between January and December 2002. A total of 244 (primarily preflexion stage of 1.7–5.7 mm in body length and 2–14 days old) and 1,285 larvae (primarily postflexion stage of 4.1–10.1 mm BL and 10–22 days old) occurred near the coast and offshore from May to August and from May to July with peaks in June and July, respectively. Monthly occurrence of larvae and their hatching dates estimated from daily rings of otoliths revealed that P. trilineatum spawn from early May to late July with a peak in June. This spawning period corresponds approximately with that of neighboring prefectures where water temperatures are relatively warmer. Considering horizontal dispersal in the early stages (preflexion to flexion), the larvae tended to immigrate to shallow waters such as shirasu fishery grounds just after attaining to the postflexion stage.
