A relationship between the number of growth increments on the otoliths and age of larval and juvenile cod, Gadus morhua L. In: The propagation of cod Gadus morhua L.: an international symposium, Arendal, 14 - 17 June 1983
Conference object
Permanent lenke
http://hdl.handle.net/11250/115102Utgivelsesdato
1984Metadata
Vis full innførselSamlinger
Sammendrag
A study of the relationship between the number of growth
increments on the otoliths and age was based on larval and
juvenile cod, Gadus morhua L., from laboratory and pond
reared populations.
Lapilli were larger than sagittae at hatching and remained
so for approximately 25 days. Sagittae became significantly
larger than lapilli at the end of the larval period. Major
growth trends of the otoliths corresponded to the growth in
standard length reported for the populations. Marked elongation
along the anteroposterior axis and formation of marginal lobes
started immedrately prior to metamorphosis.
Comparison of otolith diameter and the diameter of the
first, usually very distinct, growth increment indicated that
zone formation started somewhat before hatchlng. The diameter
of the first increment was higher in lapilli than in sagittae.
The number of growth increments, as recorded using light
microscopy, did not appear to be a constant function of larval
age between hatching and metamorphosis at age 35-40 d. The
larger of the otoliths at any given age, either the lapilli or
the sagittae, showed higher increment numbers than the smaller.
There was some indication that the rate of increment formation
was related to the individual growth rate of the larva in this
period.
In addition to the primary increments recognized in the larval
otoliths, composite broader zones appeared after metamorphosis.
These broader zones were on the average formed daily at
least until 140 days after hatching. The frequency of deposition
of these structures did not appear affected by individual
growth rate variation.
Utgiver
HavforskningsinstituttetSerie
Flødevigen rapportserie1, 1984