Fish health indicators for the Gladstone Harbour Report Card: Final project report Project ISP016c-2018

As the link between land and sea environments, estuaries are complex ecosystems vulnerable to human impacts, which directly and indirectly affect plants and animals, including fish. Fish are key biological indicators of environmental contamination, as they are water breathers, common in aquatic ecosystems, play a variety of important ecological roles, are readily identified and have high importance to the community. Various wastewater sources, of industrial, agricultural and domestic origins, can pollute downstream waterways. When fish are exposed to contaminated water, they are affected at the population level (numbers and diversity of fish species) down to biochemical impacts on single cells within individual fish. Fish health indicators range from relatively low to high cost and complexity. For this project, preference was given to testing and developing low to medium cost and complexity fish health indicators such as external measurements, pathological changes that can be seen with the naked eye, parasite count,the application of an existing health assessment index, and histopathological analysis (analysis of tissue condition using a microscope by an aquatic veterinarian). Ultimately, the results of this project will be considered for incorporation into the Gladstone Harbour Report Card, providing stakeholders and the community with accessible information about the condition of Gladstone Harbour, with potential for application to other Northern Australian ports and estuaries. The main outcome is an improved understanding of fish health in Gladstone Harbour (and beyond) leading to the potential for improved environmental and fisheries management practices, marketability of fisheries products and enhanced sustainabilityof fisheries resources. The objectives of the research project were:1.To review and identify suitable methods to monitor fish health in Gladstone Harbour. 2.To develop and implement a data collection approach to monitor fish health in Gladstone Harbour that is both cost-effective and suitable for a fish health indicator. 3.To evaluate the potential to adapt and transfer the methods and indicators developed to monitor fish health in other estuaries and ports in Northern Australia(a separate report addressing this objective is provided as Attachment B to this report). 4.To develop fish health indicator(s) based on the data collected.The key steps considered in the development of fish health indicators are: indicator selection, species selection, site selection, sample size and temporal replication.