New Zealand Journal of Marine and Freshwater Research abstracts
Age validation and growth of southern blue whiting,
Micromesistius australis Norman, in New Zealand
S. M. HANCHET
National Institute of Water & Atmospheric Research Ltd
P. O. Box 14-901, Kilbirnie
Wellington, New Zealand
Y. UOZUMI
National Research Institute of Far Seas Fisheries
7-1 Orido 5 Chome, Shimizu
Shizuoka-shi 424 Japan
Abstract Over 3000 otoliths and 100 000 length and sex
records were examined of southern blue whiting caught from commercial fishing
grounds on the Campbell Island Rise, south of New Zealand, during August and
September between 1981 and 1989. Ages of juveniles were validated by following
modes in length-frequency data over a 13-month period between September 1981
and 1982. Ages of adults were validated up to at least 10 years by following
strong year classes both from otolith-based age frequency distributions and
from length-frequency data from 1981 through to 1989. Independent analysis of
the length-frequency data using MULTIFAN further supported the adult otolith
ages. Above age 10 there was less confidence in otolith ages, less agreement
between readers and a greater degree of bias between readers. When using the
data in catch-at-age models it is recommended that ages greater than 10 be
grouped as a single plus group.
Keywords Micromesistius australis; southern blue
whiting; age validation; growth; otoliths; MULTIFAN; length-frequency
analysis
New Zealand Journal of Marine and Freshwater Research, 1996: Vol. 30:
57-67
0028-8330/96/3001-0057 $2.50/0 (c) The Royal Society of New Zealand
1996
PDF file of entire paper: medium quality (738K); (scanned from paper original: notes about this process)
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