The effect of diet on
ossification and eye migration in Atlantic halibut larvae (Hippoglossus
hippoglossus L.)
Ø. Sæle, J. S. Solbakken, K. Watanabe, K. Hamre, K.
Pittman-2003
Aquaculture, 220(1-4): 683-696
Abstract:
Larval nutrition affects post-metamorphic phenotype
in Atlantic halibut and many deformities are related to skeletal
development. In a multidisciplinary study, 24,000 sibling halibut larvae
were reared at an average temperature of 11.9 °C on either enriched Artemia
or natural zooplankton in duplicate treatments and the development followed.
One hundred and eighty sibling larvae up to about climax metamorphosis at 46
days post start feeding (psf) were cleared and stained for bone, and
stereological measurements of bone and body area and degree of eye migration
were registered. From day 21 psf, the zooplankton-fed fish had more
calcified matrix relative to body size than did Artemia-fed halibut
and from day 35 psf, this difference was significant (33.7%±1.9 SD vs.
28.6%±4.1, P<0.05). When related to ontogeny, the zooplankton-fed
fish had a higher average percentage ossification than the Artemia-fed
larvae at Stages 7, 8 and 9 (pro- and climax metamorphosis), but this
difference was significant only at Stage 8 (34.1%±2.56 SD vs. 31.9%±2.32
SD, P<0.05). Asymmetry of the cranium and consequently eye
migration began earlier (Stage 7 vs. Stage 9) and was significantly better
in the zooplankton-fed fish. The results suggest that nutritional
differences in content of vitamin A and thyroid hormones, which target
osteoblasts and osteoclasts, may underlie differences in developmental
trajectory. The results also support the hypothesis of a critical window of
metamorphosis between 14 and 25 days post start feeding in halibut larvae.
(Department of Fisheries and Marine Biology,
University of Bergen, 5020, Bergen, Norway, e-mail of K. Pittman: Karin.pittman@ifm.uib.no)