Marine and Freshwater Research
Volume 74
Number 16 2023
This work demonstrates an operational eco-viability approach to an Australian multi-species fishery, the Australian Southern and Eastern Scalefish and Shark Fishery, characterised by technical and economic interactions among harvested stocks. Biological, economic and social trade-offs are highlighted in relation to the distribution of benefits among vessel owners, fishing crews and consumers. We show that maximising economic returns conflicts with social benefits including those to consumers.
The ecological footprint of the Western (sewage) Treatment Plant (WTP) and sites where nitrogen fixation is important in Port Phillip Bay, in south-eastern Australia, were determined using nitrogen isotope ratios (δ15N). Measurements in four intertidal species and two species deployed throughout the bay showed that δ15N was elevated for all species adjacent to WTP and along the north-western shoreline of Port Phillip Bay and for ~10–15 km offshore, whereas nitrogen fixation contributed significantly to the available N in two geographically isolated seagrass-dominated bays.
Immature sharks use specific areas and environmental conditions that allow them to easily find food and avoid larger predators. The distribution and abundance of four coastal shark species were determined using survey data in the Mississippi Sound. Often the younger individuals and smaller species were distributed together, while avoiding areas of mature sharks.
The possible spawning areas of Conger eel species were found in the western South Pacific and there was a clear growth-rate difference between Conger and Anguilla larvae there. These findings help unravel the enigmatic life histories of the genus Conger in the South Pacific, which may be similar to other ocean regions. Further studies about the life histories of the Anguilliformes including Conger will contribute to understanding evolution of migration and spawning ecologies in these eels.
Giant guitarfish and wedgefish are highly exploited throughout their distribution because of their highly valued fins in the international market. This research assessed the presence and relative abundance of giant guitarfish and wedgefish species in Karimunjawa National Park (KJNP) and adjacent waters. The presence and relative abundace of the two target species, Glaucostegus typus and Rhynchobatus australiae, were low in the study area. Their presence during the study was not affected by sites, zonation or depth. This study is the first to provide information on the urgency of managing those species in KJNP.
