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.

1) The ecosystem effects of fishing need to be understood in order to work towards an EBM model for the Spencer Gulf. The South Australian government’s Marine Manager’s Forum has identified Spencer Gulf as the first area in SA for the development of a marine management plan. Better information on impacts of fishing will reduce the reliance of managers on the precautionary principle in developing management plans.
2) The important results from FRDC project 98/225: Prawn fishery by-catch and discards: fates and consequences for a marine ecosystem, are an understanding of the major components of the food chain in the trawled areas of the Gulf and the identification of the major scavenger groups on discarded by-catch. There is a need to obtain data on population impacts in order to develop trophic dynamic models.
3) A prerequisite for energy-flow models is population data outlining life history parameters, growth, migration and immigration and standing stock of, in principle, all the major species.
4) Previous research by this investigator shows that the quantitatively important scavengers on discarded by-catch in the Spencer Gulf prawn fishery are Degens leatherjackets, sealice (non-parasitic highly aggressive isopods and amphiopods), blue crabs, large stingrays and Port Jackson sharks. The effects of discarded by-catch on the population structure of these species need to be understood with the aim of developing an ecosystem model.
5) The impact of fishing on marine ecosystems (target and by-catch) on sharks, skates and rays is a world-wide problem (Stevens et al. 2000). 50% of the global catch is taken as by-catch. The catch of non-target species can have an impact at the population and ecosystem levels, particularly the removal of top predators. Elasmobranchs are at the top of the food chain in the Spencer Gulf and are important by-catch in the prawn fishery. The ecosystem level effects of fishing on the populations of these species are unknown. Discarded by-catch is susceptible to mortality. This mortality, including sub-lethal effects and post discard mortality, needs to be measured in order to predict ecosystem effects.
6) To adopt the principle of ecological sustainability in the prawn fishery, change negative public perceptions of environmental impacts, and improve fishing practices.
7) To enhance the research capacity in environmental research with emphasis on biological resource utilisation.
(Stevens, J.D., Bonfil, R., Dulvy, N.K. & P.A. Walker 2000. The effects of fishing on sharks, rays, and chimaeras (chondrichthyans), and the implications for marine ecosystems. ICES J. Mar. Sci. 57: 476-494.)

Major structural changes are occurring in several natural resource industries as the
principles of Ecological Sustainable Development (ESD), Biodiversity Conservation and
National Competition Policy are implemented. These principles are beginning to have a
significant and fundamental impact on natural resource management, at all levels of
Government and in several primary industry areas, such as forestry, agriculture and the
water industry.

The forestry industry, which bears closest parallels with the fishing industry, has
been in the forefront of these policy changes. In NSW forests: implementation of
Biodiversity Conservation principles has led to the reservation of areas traditionally
harvested by industry; implementation of ESD principles has led to the need to prepare
forestry management plans, incorporating indicators of sustainability; and, National
Competition Policies have led to the imminent corporatisation of the NSW forestry
management agency and restriction of its activities to commercial harvesting (as
opposed to other forestry management activities which will be carried out by other
departments and local community management groups).

A major problem in reforming NSW forestry has been the lack of useful forestry data
relating to biodiversity and overall sustainability (eg. faunal components of forests).
This resulted from management agencies not giving priority to collecting data on
biodiversity and has led to somewhat arbitrary decision making and eventual
confrontation. A parallel situation now exists in fisheries where, in general, very
little data has been collected on diversity of fish communities in the vast majority of
areas that are presently being fished.

In NSW, estuary management is the responsibility of many players, such as Catchment
Management Committees, River Trusts, the Department of Land and Water Conservation
(DLWC), National Parks and Wildlife Service (NPWS), as well as NSW Fisheries. For
example: the majority of estuary restoration projects in NSW are carried out by Local
Councils and Catchment Committees; DLWC is implementing "State of the Catchment"
reporting; and, "new" players, such as DLWC and NPWS, are beginning to impose
"external" constraints on fishing activities, with the objective of conserving
biodiversity. Yet very little data exist on variability and diversity of estuarine fish
communities in NSW.

While a number of agencies and groups have a role to play in estuary management,
none are likely to fund a major fisheries project at this stage. This proposed project
is a large-scale fisheries research project, relating directly to fisheries and the health of
fish communities. Every opportunity to involve other external collaborators in this project
will be explored, however only small-scale funding is likely to be achieved, leading to
a fragmented approach to this important collection of data. For example, the applicant has
already been successful in obtaining $5,000 from the Illawarra Catchment Management
Committee (ICMC) with a $10,000 extension of the project from FishCare, but none of the
sampling sites chosen by the ICMC are in areas fished extensively.

During the course of the project, the applicant will be in contact with all the relevant
agencies, such as NSW Fisheries, NSW Dept. Land and WaterConservation, NSW
National Parks and Wildlife, Local Councils and catchment groups, to ensure full
consultation takes place and that maximum collaboration is obtained.

The information to be collected during the course of this proposed FRDC project
is likely to be used widely in various management plans and reports prepared by both
community groups and Government, including:

* fisheries management plans,
* estuary management plans,
* catchment management plans, and,
* state of the environment reporting.

The inclusion of fisheries information in these reporting mechanisms would: raise the
profile of fisheries issues; encourage such data to become an established part of the
estuary health indicators; and, in so doing, help in future funding of on-going "monitoring"
programs, based on this research project. All of the above reports will be vital to the future
of the fishing industry in NSW. The NSW Fishing Industry Research Advisory Committee
(NSW FIRAC) has acknowledged the importance of the type of data collected from
this proposed project and, as a result, considered it to be amongst their highest priorities
for FRDC funding.

This project will provide data on shallow water fish communities in a wide range of estuaries
throughout southern NSW and will examine the usefulness of these data as indicators of
sustainability and biodiversity. Data on these shallow water fish communities are
comparatively easy to collect, but offer several advantages over other possible
sampling methods (see Appendix 2). The collection of environmental data at each
of the sampling sites will also provide useful information in itself, as well as important data
for the interpretation of changes in the shallow water fish populations.