Cod (Gadus morhua L.) off Møre - Composition and migration. In: The propagation of cod Gadus morhua L.: an international symposium, Arendal, 14 - 17 June 1983
Abstract
Important spawning- as well as nursery- and feeding areas
for cod, Gadus morhua L. are found off the Møre coast.
In this paper age compositions, age at first spawninq,
otolith patterns and migration of cod in the Møre area are
studied. The results are used to describe the dynamic of a
local cod population. The relationship between coastal cod
and north-east Arctic cod is discussed.
Immature coastal cod tagged off the Møre coast were mainly
stationary before maturation. When mature, cod from various
localities tended to migrate partly to the main spawning
ground off Sunnmøre, and partly to local spawning areas. A
limited number passed the Møre coast to the southern Norway
coast and the North Sea.
The otolith pattern and age at first spawning seemed to be
relatively consistent for cod from various localities off the
More coast. However, during the spawning season the influence
of older cod with a more complex otolith pattern and higher
age at first spawning gradually increased. The parameters
gradually change from those characteristic of the Møre
coastal cod to those of the north-east Arctic cod which dominated
the catches during the time of most intense spawning.
However, the original coastal cod was still present and
spawning on the same grounds.
The spawning population off Sunnmore was made up of cod
from various feeding areas, both off and north of Møre, which
to a great extent returned for repeated spawning. Further cod
in the various feeding areas off Møre were composed of groups
of fish with different migratory tendencies, including those
spawning in or close to the nursery area and long distance
migrants. The difficulties of using otoliths as an stock discriminating
parameter are discussed.
Publisher
HavforskningsinstituttetSeries
Flødevigen rapportserie1, 1984