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Abstract

Banded morwong, Cheilodactylus spectabilis, a long-lived sedentary temperate reef fish, has undergone rapid
changes in its growth and maturity characteristics along the east coast of Tasmania, Australia. Over a period of 10 years,
growth of young males and females has consistently accelerated, such that in 2005, 3-year-old fish were up to 40 mm or
13% longer compared with 1996, and age at 50% maturity for females had declined from 4 to 3 years. The magnitude
and speed of the observed changes were unexpected given the species’ longevity (maximum age of over 95 years). The
underlying mechanisms for the changes remain unclear but density-dependent responses to changes in population size and
age composition, possibly mediated through reduced competition for shelter and intra-specific interactions, may have been
contributing factors. Increasing sea surface temperatures over part of the period of change does not appear to have been a
major driver and a genetic response to fishing seems unlikely. Notwithstanding any uncertainty, C. spectabilis populations
have become more productive in recent years, challenging the general approach towards stock assessmentwhere life-history
characteristics are assumed to remain stable across contrasting levels of stock abundance and environmental conditions.

Item Type:	Article
Authors/Creators:	Ziegler, PE and Lyle, JM and Haddon, M and Ewing, GP
Journal or Publication Title:	Marine and Freshwater Research
ISSN:	1323-1650
DOI / ID Number:	10.1071/MF07137
Additional Information:	Copyright © 2007 CSIRO.
Related URLs:	Organisation
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