Otolith daily increment formation in laboratory reared larval and juvenile bluefin tuna Thunnus thynnus
T. Itoh, Y. Shiina, S. Tsuji, F. Endo, N. Tezuka-2000
Fisheries Science, 66 (5) : 834-839
(from Current Contents)
Abstract :
Otolith increments of bluefin tuna Thunnus thynnus
were examined to estimate the periodicity of an increment formation and the
timing of the first increment formation using larvae and juveniles with
known age reared in three laboratories. The increment was formed daily up to
71 days after fertilization. The first increment was formed on the fifth day
after fertilization, and around the fourth day after hatching which
corresponded to the onset of feeding. Slower growing fish had otoliths with
less distinct increments. Since wild captured larvae had otoliths with more
distinct increments, fish in the wild either grow faster than that in a
laboratory or only faster grown fish survived in the wild.
(Natl Res Inst Far Seas Fisheries, Shizuoka 4248633,
Japan, e-mail : itou@enyo.affrc.go.jp)