A fish health indicator for the 2019 Gladstone Harbour Report Card: Project ISP023-2018/19

Fish are key biological indicators of environmental contamination in waterways including estuaries, as they are the dominant taxa by biomass, play a variety of important ecological roles, are continuously exposed throughout their life cycle, are readily identified and have high importance to the community. When fish are exposed to contaminated water, they can be affected from the population level (numbers and diversity of fish species) down to biochemical impacts on single cells within individual fish. In 2018, Gladstone Healthy Harbour Partnership (GHHP) and the Fisheries Research and Development Corporation (FRDC) commissioned CQUni to investigate potential fish health indicators for the Gladstone Harbour Report Card and suitable for adaptation across ports and estuaries of Northern Australia. The research identified and tested a range of potential indicators that were low-medium cost and complexity. The indicator that was found to be most suitable for the Report Card is a version of the Health Assessment Index (HAI), a composite metric that integrates observer evaluations of multiple organs and tissues. The premise of the HAI is that scores will cumulatively reflect the acute and chronic stressors present in the fish’s environment, with poorer anatomical condition resulting in higher HAI scores, indicative of a more stressful environment. In 2019, GHHP commissioned CQUni to continue to monitor fish health in Gladstone Harbour using methods developed in 2018 and provide scores and grades for the Gladstone Harbour Report Card.