New Zealand Journal of Marine and Freshwater Research abstracts

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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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