Identifying biological stocks of Silver Trevally and Ocean Jackets for assessment and management
This application is required primarily to address the needs of FRDC and the SAFS advisory group to resolve stock uncertainty for two priority species across their national distributions, being Silver Trevally and Ocean Jackets.
The results will inform future SAFS assessments that will ideally be done at the biological stock level. In addition, understanding appropriate scales for assessment and management will benefit future collaborative research, stock assessments and management arrangements. In particular, Silver Trevally in eastern Australia is recognized as being Depleted in NSW waters, yet if there is a single biological stock also being fished by neighbouring jurisdictions (for example the Commonwealth fisheries) there will need to be improved collaboration in terms of stock assessment and management to recover the stock.
All relevant jurisdictions have identified the need to resolve stock structure of Silver Trevally and Ocean Jackets as they are important to commercial and recreational fisheries across their distributions.
Final report
Identification of factors which impact on the profitability of individual GABTS operators and the fishery as a whole
Isolating social and economic objectives within multiple stakeholder fisheries – a case study: the South Australian Marine Scalefish Fishery
Realising economic returns of reducing waste through utilisation of bycatch in the GAB Trawl Sector of the SESSF
Bycatch and discard issues remain a serious problem in the management of trawl fisheries around the world. The EU is currently investigating a revised fisheries policy to minimize/ban discards to minimise environmental impacts and to account for all fishing mortality within catch estimates. Many discarded fish are dead or die soon after being returned to the sea - a practice seen as wasteful and a potentially negative ecological impact.
Despite improved bycatch reduction introduced over the last decade, many Australian trawl fisheries continue to discard more than is retained. Despite discard rates for the main target species of the GABTS (Deepwater Flathead, Bight Redfish, Orange Roughy and Western Gemfish) being very low (2% for DWF, BRF and OR and 10% for WGF), the bycatch of “other species” accounts for up to 50% of the total catch being discarded. GABIA and GABRAG have identified the potential of the GAB Trawl Sector to move towards becoming a ‘zero discards’ fishery. Although this may be the ultimate goal, they sought for this project to explore the maximum potential for bycatch utilisation through development of markets for human consumption of certain species and the potential conversion of all other bycatch species fish silage for use in food supplements, animal feed, nutraceuticals or fertilisers).
GABTF tralwers operate with low economic returns. Apart from the potential value of bycatch utilisation to increase their profitibility, it may also create additional market access for the fishery through demonstrated socially responsible fishing practices. An assessment of the feasibility of such an approach in the GAB Trawl fishery would represent a useful exploration of the potential of such an approach in other Australian trawl fisheries.
Final report
Fisheries bycatch reduction and utilisation is an important topic in the western world in both policy and research developments. At an international level, the FAO Code of Conduct for Responsible Fisheries directs management agencies and fisheries to reduce discards through development and implementation of technologies and operational methods, including reducing post-harvest losses and waste and improving the use of bycatch to the extent that this is consistent with responsible fisheries management practices. Australian management agencies and fisheries also seek to minimise bycatch in line with international guidelines, and specific domestic policies, objectives and community expectations.
Bycatch issues can be addressed by fishers (targeting practices), the supply chain (increased utilization) and by consumers (wider purchasing habits). There are a range of issues associated with these strategies, which may impact on the portfolio of approaches to minimise wastage. Here, we examine options to utilise fish that are currently discarded to both decrease wastage and increase profitability of the Great Australian Bight Trawl Sector (GABTS).
Tactical Research Fund: Empowering Industry R&D: Trials of T90 mesh configuration for bycatch reduction and more efficient fishing in the Great Australian Bight Trawl Fishery
There is an obvious need to reduce bycatch in the fishery consistent with mandatory legislative and policy requirements (EPBC and FMA) and to develop more efficient harvest protocols. Consistent with this, GABIA has provided full support for the introduction of T90 mesh into their fishery through the mandatory use of T90 extensions and/or codends from 1 January 2007. Potentially, even greater benefits are possible with a move to T90 gear from the wingends to codend. Such nets have been tested and shown to be effective in some Icelandic fisheries.
Modifications to gear (particularly the very recent move to full T90 nets in some overseas fisheries) have been shown in other fisheries to be effective in reducing fuel consumption consistent with the need to reduce operating costs and to reduce greenhouse gas emissions in the fishing industry. This proposal aligns to priorities of reducing environmental impacts of trawl fisheries and of increasing operating efficiency and industry profitability.
Final report
Determining appropriate sizes at harvest for species shared by the commercial trap and recreational fisheries in New South Wales
Available evidence suggests that most fish species harvested by the NSW demersal trap and recreational fisheries are taken at sizes that are too small to optimise yield and/or economic return. This is because most species taken in both of these fisheries either have MLL’s that are too small or do not have MLL's at all. There have only been stock assessments done on snapper (FRDC project No. 93/074) and silver trevally (FRDC project No. 97/125) in the trap fishery. Both studies showed that they were growth overfished and the results have been used to increase the MLL for snapper and to impose a MLL for silver trevally across all fisheries. Many other species taken by fish traps are in decline and it is highly likely that they are also growth overfished. Unfortunately, very little is known about the biology or life-history of these other species. Recreational fishers are significant harvesters of all species taken in the NSW demersal trap fishery and it is important that any MLL’s designed to reduce overfishing are applied across all fisheries.
NSW Fisheries does not currently have a policy for setting MLL's at particular sizes and the process developed during this study may form the basis for such a policy. It is important to consider several issues when setting appropriate harvest sizes and these include: (i) the size at sexual maturity; (ii) the size that will optimise yield; (iii) market requirements; (iv) an economic assessment, and (iv) public perception.
The information on biology, stock-assessment and protocols for setting appropriate harvest sizes developed during this project will directly address several key areas of importance recognized by the FRDC. The planned outcomes will lead to fisheries management being based more on the precautionary principle, will maximise the economic and social returns from harvesting these species while also providing for effective management of recreational fishing. These areas are considered to be high priorities by the NSW FRAB and by Recfish Australia in their National Research and Development plan for the recreational sector.
Final report
Mesh selectivity in the NSW demersal trap fishery
Reduction of by-catch has been an active area for research in Australia and around the world. The initial focus for research and management has been demersal trawl fishing, where the perception of waste and potential impact has been the greatest. However, the reasons for seeking to reduce unwanted catch apply to all fisheries, including those using demersal traps.
Demersal fish traps in NSW must be covered with mesh no smaller than 50 mm, and a galvanised hexagonal fencing wire is the most common material. However, many fishers use larger mesh and both 50 X 75 mm and 75 mm hexagonal mesh are in use. Those using and advocating larger mesh have done so to reduce the catch of undersize snapper and other small fish and to decrease sorting times. Other trappers are concerned about the effect of larger mesh dimensions on the catch of valuable species such as wrasses, sweep or bream which all have no minimum legal length (MLL) or have an MLL smaller than snapper.
An understanding of the differences in selectivity of different sizes of mesh on the species caught in fish traps will have a number of uses. This information is essential to determine the cost and benefit to fishers of changing mesh sizes. The selection probabilities for existing meshes can also be used to improve the assessments using age and length composition collected for snapper and bream in NSW. This is particularly important for snapper, where a very large proportion of the fishery is caught close to the MLL. Finally, because wire mesh can be made in a diversity of shapes and sizes, it may be possible to achieve desirable changes in selectivity for some species while not changing selectivity patterns for others.