The Freshwater Sawfish Pristis microdon was captured in marine waters of King Sound, and estuarine and fresh waters of the Fitzroy and Robinson rivers, in the Kimberley region of Western Australia. In light of the IUCN listing of the species as critically endangered, non-destructive means, including tagging-recapture data and information from specimens found dead on the banks, were utilised. Observations of sexual maturity, annuli present on vertebrae, recaptures of tagged individuals and length-frequency data suggested that the freshwaters of the Fitzroy River are a nursery for this species where immature individuals (up to 2800 mm total length) remain for a maximum of four or five years. Morphology and counts of the number of rostral teeth indicated that, in most cases, the rostral tooth morphology can be used to differentiate male and female P. microdon and also are useful in distinguishing this species from the congeneric and sympatric Pristis clavata. Furthermore, differences in the relationship between rostrum length and total length between the sexes may provide an effective diagnostic tool for the collation of historical distribution and sex ratio data from rostrums held in private collections. Rostral tooth counts and length at age data also suggest that the synonymisation of P. microdon, Pristis zephyreus and Pristis perotteti is not warranted.

The dwarf sawfish, Pristis clavata, was captured in marine waters of King Sound and estuarine waters of the Fitzroy, May and Robinson Rivers, in the Kimberley region of Western Australia. Observations of sexual maturity and annuli present on vertebrae suggest that the estuarine waters of at least the Fitzroy River act as a nursery for the species, where immature individuals may remain for at least 3 years. The capture of immature individuals in excess of 2,330 mm TL during the current study in addition to Peverell's (Peverell in Environ Biol Fishes 73:391-402, 2005) record of a mature male measuring 3,060 mm TL implies that the species may attain far greater lengths than previously reported and that the common name may not be entirely appropriate. In contrast to the sympatric freshwater sawfish Pristis microdon, the number of rostral teeth of individual P. clavata can not be used to differentiate males from females, with both sexes possessing an average of 42 rostral teeth.

The potential impacts of introducing barramundi ( Lates calcarifer ) for the purpose of recreational fishing into Lake Kununurra, a tropical impoundment in the Kimberley region of Western Australia, are predicted by dietary comparisons with the resident fishes of the lake. Classification of the pooled dietary data identified five major feeding groups based on similarities in food items consumed. There was no significant dietary overlap between L. calcarifer and all species within the lake. The current study demonstrates that adult L. calcarifer fed primarily on teleosts and decopods, and are known to prey on the majority of the fish species found in Lake Kununurra. Although the introduction of L. calcarifer to Lake Kununurra has the potential to influence the resident fish community through competition (for food and habitat) and predation, it is likely that its effects will be minor. However, the lack of any data that would allow estimation of the likely survival of stocked L. calcarifer fry and fingerlings in the reservoir needs to be addressed. Such data are mandatory if a successful fishery is to be developed in the reservoir.

The Exmouth Integrated Artificial Reef (King Reef) was deployed in July 2018 and is the first installation in Australia to innovatively combine repurposed oil and gas infrastructure with purpose-built concrete reef modules. The project involved a collaborative approach between industry, government (state and commonwealth), researchers and the community, creating a world-leading engineering solution using science-based habitat enhancement. The project integrated six mid-depth buoys with 49 artificial reef modules, providing more than 27000 m3 of habitat. Once support structures for subsea facilities, the decommissioned assets are now important habitat features that increase ecosystem productivity. The unique design and configuration of the structures on the sea floor resulted in a rapid increase in the diversity and abundance of marine biota, as detected by a collaboration between citizen scientists and researchers. Within 2 years, over 90 species of fish have already been observed, which is much greater than the sand habitat upon which the reef was installed. The results contribute to informed discussions, about the viability and effectiveness of artificial structures providing industry, regulators and the community with confidence around the benefits and effects of various installations. The Exmouth community has been advocating for the installation of an artificial reef for several years. At King Reef, the integration and repurposing of assets provide a range of long-term benefits to communities, including fostering community ownership and stewardship of these assets while providing new, safe and accessible fishing and diving opportunities.

No abstract