MEPS 273:199-210 (2004)  -  doi:10.3354/meps273199

Population structure of aggregations, and response to spear fishing, of a large temperate reef fish Cheilodactylus fuscus

Michael Lowry1,2,*, Iain Suthers1

1School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, New South Wales 2052, Australia
2Present address: NSW Fisheries, PO Box 21, Cronulla, New South Wales 2230, Australia

ABSTRACT: Strip transect surveys of the large temperate rocky reef fish Cheilodactylus fuscus revealed size- and sex-structured populations across seasons and 3 conditions of wave exposure, from an estuary to the open coast. Large, mostly male, fish (>30 cm fork length) predominated on the open coast and in deeper water (>10 m), while smaller fish predominated in the more protected estuarine areas and in the subtidal regions (<5 m), particularly during the winter to spring recruitment period. Aggregations of C. fuscus were geographically persistent, varying in their size and sex composition over 2 yr, which suggested an ontogenetic migration from shallow and protected areas to more exposed coastal locations. Reasons defining the location of aggregations were unclear, as multivariate analysis of 29 habitat characteristics of 13 aggregation sites versus 6 similar control sites revealed no significant difference. Fish re-colonised the same location 2 to 4 mo after a summer and a winter experiment removed >70% of the adults by intense spear fishing. Experimental sites were recolonised by >20 cm males and females, and rarely by juveniles. There was no significant difference between the pre- and post-removal estimates of home range of tagged fish at removal sites or in controls.

KEY WORDS: Cheilodactylidae · Habitat use · Population structure · Disturbance · Spear fishing · Environmental impact

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