New Zealand Journal of Marine and Freshwater Research abstracts
Age and growth of Cheilodactylus fuscus, a temperate rocky reef
fish
Michael Lowry
School of Biological Science
University of New South Wales
Sydney
NSW 2052, Australia
Present address: NSW Fisheries, P.O. Box 21, Cronulla, NSW 2230, Australia.
email: lowrym@fisheries.nsw.gov.au
Abstract To provide information on age and growth
of red morwong (Cheilodactylus fuscus Castelnau), populations were
sampled from eight locations over a 2.5-year period with the majority of
fish sampled from six sites within Sydney Harbour, New South Wales, Australia.
Transverse thin sections of otoliths taken from a total of 347 fish were
used to determine age. Age estimates were validated using oxytetracycline
(OTC) marking and marginal increment techniques. Validated otoliths indicated
that this species forms one annulus per year over an extended period from
April to October. Age varied from “0” (<1 year old) to 40 years. A comparison
of otolith weight and otolith radius determined that otolith weight was the
more accurate physical determinant of age. Von Bertalanffy growth estimates
based on length (t0 = -1.8, k = 0.32, L∞= 37.64) indicated that
growth is most rapid over the first 6 years, with fish being close to their
asymptotic length by 7 years. There was no significant difference in length
between sexes although females were significantly older than males. Comparisons
of growth curves did not indicate any significant differences in the rate
of growth between sexes.
Keywords Cheilodactylus fuscus; monitor; morwong;
age; growth; sagittae; validation
M02014 Received 4 March 2002; accepted 4 November 2002; Published 20 March
2003
New Zealand Journal of Marine and Freshwater Research, 2003, Vol. 37:
159-170
0028-8330/03/3701-0159 $7.00 © The Royal Society of New Zealand
2003
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