| dc.description.abstract | Recently several research projects have involved studies
of cod in the Møre area. Due to a common sampling programme
a large number of individual fish have been classified for
biological and genetical characters. The genetical study
included analyses of mature fish, juveniles and eggs/yolksac
larvae, and all samples were analysed for polymorphic proteins
by using electrophoresis combined with selective staining
methods. A significant amount of heterogeneity, expressed as
variation in genotype distributions and allele frequencies,
was observed among cod samples from this area, suggesting a
rather complex stock structure.
Samples which were taken during spawning consisted of a
mixture of Arctic and coastal cod. Some of these samples
permitted comparisons between biological and genetic data.
The correlation between otolith structure and the allele
frequencies for the enzymes analysed was not as significant
as in earlier studies on blood factors and blood proteins.
Significant differences between the two groups of cod were
detected for two proteins (lactate dehydrogenase and haemoglobin),
confirming the results from earlier genetical
studies of cod in this area.
The variation observed in different samples of coastal cod
was very complex and difficult to interpret in terms of a
reliable stock model. At present, however, the genetical
data on spawning samples of coastal cod indicate a distinct
stock in the Smøla region. In the Sunnmøre region the
preliminary analyses of cod eggs taken on the main spawning
ground at different times suggest more than one spawning
group. This new sampling approach seems to be very useful in
studies of fish gene pools. With regards to the stock '
structure of coastal cod in this area, we feel that genetic
analyses of cod eggs on locally distributed spawning grounds
will provide the most reliable information. | en |
