Induced spontaneous spawning using an increased temperature stimulus
in the cultured barfin flounder Verasper moseri
T.
Kayaba, T. Sugimoto, T. Mori, N. Satoh, S. Adachi, K. Yamauchi-2003
Fisheries
Science, 69(4):
663
Abstract:
The
present study examined the potential to induce spontaneous spawning in
cultured barfin flounder using increased temperature as a stimulus; that is,
increasing the rearing temperature from 6 to 8-9°C over 6 h in the
morning and reducing it to 6°C the following morning. In 1997 and 1998,
cultured barfin flounder, aged 3 years, were reared under two water
temperature regimens. In the brood stock groups reared at fixed temperatures
(6 or 8-9°C) during the spawning season, all females ovulated normally and
released eggs into the aquarium; however, almost all eggs were unfertilized.
In contrast, in groups reared with periodic stimulation with increased
temperature, the number of eggs collected per day was greater than that from
groups without stimulation. Furthermore, fertilization was induced
frequently throughout the experimental term and the number of fertilized
eggs obtained was much greater. Estimation of fertilization time indicated
that fertilization occurred largely within 24 h after the stimulation
was conducted. Moreover, in 2000, the fertilization rate of fish reared with
periodic stimulation was very much higher than that in fish without
stimulation. These results demonstrate that performing periodic increased
temperature stimulation during the spawning season is effective in
accelerating egg release in females and also in inducing fertilization of
cultured barfin flounder in rearing conditions.
(Hokkaido Institute of Mariculture, Kayabe, Hokkaido
041-1404, Japan, Tel: 81-1372-7-2234. Fax:
81-1372-7-2235. Email:
kayabat@fishexp.pref.hokkaido.jp)