Looking after Gladstone’s iconic giant mud crabs
Giant mud crabs are one of the most commercially valuable shellfish, a key fisheries resource for Queensland, and hold cultural value for Indigenous Australian peoples. But despite their ecological, economic and social importance, there remain significant gaps in the understanding of mud crab biology and ecology. In 2017, the Gladstone Healthy Harbour Partnership (GHHP) commissioned CQUniversity to develop a mud crab indicator for the Gladstone Harbour Report Card, and a long term monitoring program to continue to score and grade the indicator annually.
Gladstone Harbour boasts ideal mud crab habitat of mangrove-lined estuaries and is a key commercial and recreational fishing region, which project lead Associate Professor Nicole Flint says made it the perfect location to study mud crabs.
“The mud crab indicator is composed of three different measures that were designed to reflect the range of environmental and extractive pressures in Gladstone Harbour. Working with the Indigenous Sea Rangers from Gidarjil Development Corporation, each year we compile information on catch rates, sex ratios (the ratio of males to females)
and the prevalence of rust lesions,” Associate Professor Flint says.
“This provides a valuable comparison over time and we have we been able to refine the
indicator as new data and information has become available.”
Associate Professor Nicole Flint says the ongoing partnership with GHHP allows the research team to work continuously to identify new data that could feed into the indicator and scoring methods.
“The mud crab indicator is used to independently monitor, and report on, the health of the harbour against GHHP environmental goals, and inform annual Gladstone Harbour Report Cards
“Before this, mud crabs had not been included in ecosystem health report cards in Australia or elsewhere in the world,” she explains.
“We recently completed our sixth year of monitoring, providing scores and grades for the 2022 report card, and building a long-term dataset to better understand these important animals.”