Mud crabs sandwiched into environmental monitoring toolkit

Published:06 August 2018

CQUni researcher Dr Nicole Flint and her team catch mud crabs at seven sites in Gladstone Harbour. Each crab is measured, weighed, graded, checked for lesions or other abnormalities and released alive at the capture location.

The Gladstone Healthy Harbour Partnership has been able to add a mud crab indicator to its annual report card, thanks to new research by CQUniversity.

CQUni researcher Dr Nicole Flint says a new indicator compiling information on abundance, sex ratios (the ratio of males to females) and the prevalence of rust lesions will be a valuable means of comparison over time.

The CQUni team catches mud crabs at seven sites in Gladstone Harbour. Each crab is measured, weighed, graded, checked for lesions or other abnormalities and released alive at the capture location.

Dr Flint says the CQUni team also has funding from the Gladstone Healthy Harbour Partnership (GHHP) to monitor mud crabs in an unfished creek in the 1770 area, as a point of comparison with fished areas in Gladstone Harbour.

She says the new data will be useful to compare how fishing affects male-to-female ratios, both within Central Queensland and in comparison with other unfished areas in Moreton Bay and overseas. This may allow other effects of general environmental condition on sex ratios to also be identified.

The new indicator was piloted in 2017 and monitoring continues during 2018 for the next report card.

A fourth component for the mud crab indicator (relating to the size, weight and condition of individual mud crabs) is also being developed.

A technical report detailing the science behind the mud crab indicator is available on GHHP’s website: https://dims.ghhp.org.au/repo/public/2b561b