Growth patterns in the North Sea and western mackerel in Norwegian catches 1960- 85
Original version
This report is not to be cited without prior reference to the authorAbstract
Length, weight and age in random samples from Norwegian catches of'
mackerel from 1960 to 1985 have been reviewed. A standard growth curve
was constructed by applying a modified von Bertalanffy equation to all
data. The deviation from this curve is largely independent of age for
adult mackerel, and may be used as a measure of the growth pattern. In
the North Sea area, the length at age has increased gradually by 4-5
cm during this period, while it has been nearly stationary in the
western spawning area. The condition has remained stable in this
period. The mackerel caught in the North Sea is generally larger at
age than the typical Western mackerel, even in the years and seasons
when Western mackerel dominated in the cathes in the North Sea. The
mixing of two stock components with different growth patterns also
makes the use of length distributions as a measure of age
distributions questionable.