Assessment of the effects of fishing and its environmental impacts are key research areas identified as high priority for Australia’s fisheries management and funding agencies. Australian fisheries are now being required to demonstrate their environmental sustainability through an Environment Australia assessment process. This requirement is being driven by new legislation such as the EPBC Act and by industry through the need for meeting standards for certification e.g. accreditation by the Marine Stewardship Council.
To date there has been no study of the effects of trawling on the seabed invertebrate communities in the NPF. A CSIRO-QDPI study of the impacts of trawling on inter-reef seabed communities in the northern GBR (Poiner et al. 1998) showed that in inter-reefal areas, trawling caused an overall depletion of seabed fauna of between 5 to 20% for each trawl and the effect was cumulative. However, this inter-reef seabed is not typical of most prawn trawl grounds, which are muddier and have a different fauna. The CSIRO-QDPI study recommended that a future study should quantify the response of soft-sediment fauna to trawl disturbance. This proposal aims to do this and addresses NPF High Priority Research Areas: Effects of fishing (improved efficiency in fishing gear and techniques in order to reduce bycatch and discarding and environmental impacts on the benthos).
Some sectors of society recognize prawn trawling as one of the main extractive activities in tropical seabed areas of Australia, and there is an increased pressure to limit its perceived impacts. However, if these practices are to continue, how do we ensure that the effects of trawling on the seabed are sustainable? It is imperative to evaluate conservation and management options for the seabed and develop indicators for the status of the seabed and impacts of the fishery. In order to achieve this, we need to know:

-The fine-scale spatial extent of the fishing effort within the NPF
-The mortality rates of different species of seabed fauna under different fishing impact intensities.
-The rate of recovery of impacted seabed fauna.
-The likely response of the seabed fauna under different management options.
This project will address these questions. The compilation and mapping of the available VMS data will provide an accurate depiction of the overall combined fishing effort over the whole of the fishing grounds. The repeat trawl experiment will provide estimates of trawl-induced mortality rates of various seabed fauna. The recovery of these species will be monitored at 6-monthly intervals for 2 years after the repeat trawl experiment. These data will be incorporated into the Trawl Impacts Model and the responses of seabed fauna to a variety of management options will be modeled. Data derived in this project will enable us to increase confidence in the outputs of the model and provide more soundly based advice to managers. However, a future complimentary project to characterise the seabed fauna over broader geographic regions, including a range of fishing effort would be needed to increase and expand our confidence in the predictions from the model for the whole of the NPF.

The management of northern elasmobranchs has a strong need for research to address local and regional management issues. The need is fundamental, the Northern Shark Stock Assessment Review Workshop (QLD, NT, WA and the Commonwealth), Broome 2000, identified the lack of species identification in NT and QLD catches in target and bycatch fisheries as a major concern. This has been clearly recognised at State/Territory, national (NAFM) and international (FAO, IUCN) levels. The sustainability of these species is also an explicit priority with stakeholders. The Northern Australian Fisheries Management (NAFM) Workshop (QLD, NT, WA and the Commonwealth) identified research into elasmobranchs as high priority in 1998, 1999, 2000 and 2001. The NAFM Workshop agreed to write to FRDC to reiterate the high priority of this project. Professor Carl Walters, at a Stock Assessment Workshop in Darwin, examining northern shark catches, also highlighted the issue of inadequate data (Walters and Buckworth 1997) while the National Shark Advisory Group (Nov. 2000) also identified similar issues. There is also a clear need to determine the extent of shared stocks, both within Australia and with Indonesia, to ensure the management scale is appropriate. This project will also address the critical need for information on the biology and catch of sawfishes in northern Australia, research for which Environment Australia have also indicated their support. The first phase of this project (Jul 2001 - Jul 2002) received a high priority from QFIRAC 2000 and was funded by FRDC (FRDC 2001/077). Environment Australia and ACIAR have also funded complementary research on sharks and rays in northern Australia and Indonesia. The current project is critical to ensuring these studies have valid, up to date information on the current catches in northern fisheries. QFIRAC has given this project very strong support, ranking it second of all proposals submitted.