The interrelation of growth
and disease resistance of different populations of juvenile Atlantic halibut
(Hippoglossus hippoglossus L.)
A.K. Imsland, T.M. Jonassen, A. Langston, R. Hoare,
H. Wergeland, R. FitzGerald, M. Mulcahy, S.O. Stefansson-2002
Aquaculture, 204(1-2): 167-177
Abstract:
Growth of juvenile Atlantic halibut from three areas
of the North Atlantic (Canada, Iceland and Norway) was studied in an
experiment using individual tagged fish reared at 15°C for 85 days. Fish
from each population were subsequently split into two groups and
acclimatised to either 12°C or 18°C. The fish were then injected
intra-peritoneally with a Vibrio anguillarum bacteria suspension and
mortality monitored for 4 weeks. Growth rates of the Canadian population
ranked lowest, whereas the Norwegian population had the highest mean growth
rates (SGR=1.70%/day, 1.62%/day and 1.53%/day for the Norwegian, Icelandic
and Canadian populations, respectively). The halibut from Norway had the
best survival following bacterial challenge (80%, 50% and 55% survival for
the Norwegian, Icelandic and Canadian populations, respectively). Mortality
was higher at 18°C than at 12°C in the Icelandic (62% at 12°C and 27% at
18°C) and Canadian (56% at 12°C and 32% at 18°C) fish, whereas a smaller
difference between temperatures was observed in the Norwegian fish (25% at
12°C and 13% at 18°C). Fish that survived the challenge test were those
that had grown fastest in the growth trial. Low, but significant,
correlations between survival and size and growth were seen, but these
correlations varied between populations. In the Canadian population, no
correlation between size and growth and survival were seen; only size was
correlated (r=0.27) with survival in the Icelandic population,
whereas both size (r=0.18) and growth (r=0.17) were correlated
with survival in the Norwegian population.
(Department of Fisheries and Marine Biology,
University of Bergen, High Technology Centre, P.O. Box 7800, N-5020 Bergen,
Norway, Tel.: +354-525-3600; fax: +354-525-3608, e-mail: alberti@uvs.is)