Relative growth and feeding habits of halfbeak, Hyporhamphus sajori, larvae and juveniles in Toyama Bay [Japan] of the Japan Sea
2002
Oya, F. (Marine Biological Research Inst. of Japan Co. Ltd., Tokyo) | Tsuji, T. | Fujiwara, S.
Relative growth and feeding habits of larvae and juveniles of the Japanese halfbeak, Hyporhamphus sajori, was assessed from data collected during a field survey in the summer of 1999. The lower jaw started to elongate from about 10mm TL In the allometric relationship between lower jaw length and total length, a turning point was calculated from the intersection of regression equations at 28mm TL. This point corresponds with the total length completed at metamorphosis. Halfbeak larvae smaller than 30mm TL fed mainly on copepod nauplii such as Oithona spp. and Paracalanus type. Larvae larger than 60mm TL fed on larger items such as insects, harpacticoid copepods and organic detritus. In specimens beyond 57mm TL, the rate of body weight increase with total length was greater and was apparently due to a change in dietary items.
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