Do estuarine no-take reserves affect the abundance and length frequencies of fishery target species - an assessment of two north Queensland estuarine 'no-take' marine park zones.

Abstract

Fish traps, crab pots and baited drift lines were used to compare abundance and length?frequency distributions of fish and crab target species between no-take reserves (NTR) and adjacent areas open to fishing in the Daintree and Moresby Rivers of north-eastern Australia. Tide speed and wind direction limited the effectiveness of baited drift lines. Catch rates in the fish traps were so low that only overall fish captured (total fish), pikey bream, Acanthopagrus berda, and mud crabs, Scylla serrata, were sufficiently abundant for analysis of abundance. Of those taxa, only male S. serrata in the Daintree River and female S. serrata in the Moresby River showed any significant differences between zones. In both cases relative abundance was higher in the open zone. Those differences were not found in crab pot samples where male S. serrata in the Moresby River were significantly more abundant in the NTR. In terms of length frequency, greater proportions of larger A. berda and male S. serrata were captured in the Moresby NTR than outside. All non-significant results exhibited low power due to high variability and low catch rates. Although circumstantial without pre-closure data, results indicate that NTRs may lead to larger average sizes and higher abundances of male S. serrata in the Moresby River.