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A Preliminary Assessment of Two North Queensland Estuaries Containing 'No-Take' Fish Reserves - Quantifying the Variability in Relative Abundance and Length Distributions of Target Species
Karen Rudkin, John Kirkwood, Jean-Marc Hero and Michael Arthur
Griffith University Gold Coast, TUGUN, AUSTRALIA
Theme: TH4
The use of no-take marine reserves (NTRs) as a fisheries management tool has gained considerable support in recent years. This study used fish traps and crab pots to compare fish and crab target species abundance and length frequency distributions in the NTR and adjacent open areas of the estuarine reaches of both the Daintree and Moresby Rivers. Fish catch rates for traps were low therefore only overall fish captured (total fish), pikey bream, (Acanthopagrus berda), and mud crab (Scylla serrata) were analysed for abundance. Daintree River male S. serrata and Moresby River female S. serrata showed significant differences between zones with relative abundance higher in the open zone. Moresby River male S. serrata captured in crab pots was the only result consistent with the hypothesis that abundance would be higher in the NTR. A greater proportion of larger individuals of Moresby male S. serrata and Moresby A. berda were captured in the NTR. All non-significant results exhibited low power due to high variability and low catch rates. Detecting observed effect sizes with power required unrealistic sample sizes for all non-significant results. This study has shown that fish traps may not be an appropriate method for a general census of target fish species populations. Although circumstantial without pre-closure data, results indicate that the NTR may be having a beneficial effect for Moresby male S. serrata.
