Effects of photoperiod on
sexual maturation and somatic growth in male Atlantic halibut (Hippoglossus
hippoglossus L.)
B. Norberg, F.-A. Weltzien, Ø. Karlsen, J.C.
Holm-2001
Comparative Biochemistry and Physiology – Part B:
Biochemistry and Molecular Biology, 129(2-3): 357-365 (4th
International Symposium on Fish Endocrinology)
Abstract:
A major obstacle
in modern, intensive aquaculture is the precocious maturation of male fish,
leading to decreased somatic growth and reduced filet quality. Effects of
photoperiod on sexual maturation and growth in male Atlantic halibut were
therefore examined. In June 1996, 1300 1+ fish of both sexes were
distributed in two indoor tanks supplied with continuous light (LL) or a
simulated natural photoperiod (SNP). In December 1996 and June 1997, 200
individuals were exchanged between the tanks creating six experimental
groups that were followed until June 1998. LL stimulated growth and
accelerated timing of first maturation by approximately 3 months. LL also
appeared to interrupt circannual rhythmicity in sexual maturation. Sexual
maturation led to reduced growth from 3 months pre-spawning and throughout
the spawning season. Males that did not mature during the experiment
attained the highest final body weight. All males reared on LL from June
1997 reached sexual maturity the following season. In contrast, only 26% of
the males matured in the group transferred from LL to SNP in June 1997, and
this group also had the highest final body weight. The results indicate a
possible route for reducing the problem of precocious maturation in male
halibut.
(Institute of Marine Research, Austevoll Aquaculture
Research Station, N-5392 Storebø, Norway, Tel.: +47-56-18-03-42;
fax:
+47-56-18-03-98, e-mail: birgitta.norberg@imr.no)