Over 300 species are caught in the SEF, of which around 100 have commercial value. Twenty five species comprise around 90% of the landed catch. Each year, however, quotas are set for only around 17 species. There are 10 of these species for which there is (or has been) some formal stock assessment (that may not occur every year). For all of the remaining quota species and some of the more important non-quota species, no formal assessment is undertaken and the only assessment that can be made is based on investigation of trends in catch and effort and size distribution and anecdotal input from scientists and industry. There is simply not enough resources to undertake formal stock assessments for the wide range of commercial species landed in the SEF. Yet, each of these species is an important component of the catch of fishers. If the fishery is to continue to operate in its current form and meet the strategic assessments required under the EPBC Act, some form of formal assessment is required.

A recently completed ARF project (Production parameters from the fisheries literature for SEF-like species - Project no R99/0308) demonstrated the utility of using information for "similar" species when conducting assessments for SEF species. Using key parameters such as the virgin biomass, the rate of natural mortality, and the “steepness” of the stock-relationship relationship, a simple formula was developed for identifying “similar” stocks / species and an algorithm was developed for constructing prior probability distributions for these parameters. The resultant distributions can be used in Bayesian stock assessments and as the basis for sensitivity tests when applying other methods of stock assessments. The current project will refine the prior distributions for the production parameters and develop and test methods of stock assessment that use the results of assessments for well-studied species in a formal manner to inform assessments of ‘data-poor’ species. If successful, the methods developed would lead to significant benefits not only for the assessment and management of "data poor" SEF low priority, by-product and by-catch species, but also for a range of new and developing fisheries in Australia.

The uncertainty in the SBT catch at age matrix has been identified as one of the main sources of unaccounted uncertainty in the SBT stock assessments. The robustness of of the assessment to this uncertainty is unknown. Moreover, a critical issue in the SBT stock assessment is the internal inconsistency that exists among the inputs data and the need to develop improved models that can provide consistent interpretations for all of the available data. These inconstancies are making it increasing difficult to provide robust and scientifically objective conclusions about short term changes in the status of the SBT population. The model used for estimating SBT growth rates has been identified as a likely factor contributing to the apparent inconsistencies in the data. The current model of SBT growth was developed in 1993/94 and make simple assumptions about how growth may have changed since 1951. It assumes that growth rates since 1980 have remained equal to those measured by the 1983/84 tagging program. The current model fails to address the question of whether growth may have increased with the continued declined in the SBT stock since 1980 or the question of whether growth may decrease in the future if the population recovers. Given that incorporation of change in growth between the 1960s and 1980s had significant effects on the stock assessments and substantially reduced estimates of the probability of recovery, it is critical for the provision of reliable assessments and management advice that changes in SBT growth are appropriately and accurately accounted for in the analyses.

Since the currently used growth models were developed, substantial amounts of new information has been collected on SBT growth based on direct aging, otolith increment measurements and tagging experiments conducted in the 1990’s. Initial analyses of some of these data suggest that the assumptions about changes in SBT growth embedded in the current models are likely to be inadequate. There is a need to incorporate these new data within a comprehensive analysis and to develop an integrated model for all the various sources of information on SBT growth. Such an integrated model should provide the basis for addressing uncertainties associated with the catch at age matrix within the SBT stock assessment. Such an integrated growth model would allow for the development of improved assessment models. Such models are needed in order to be able to provide consistent interpretations of the available input data and thus improve the reliability and robustness of the management advice based on these models.

There is considerable scope to enhance spatially-based management arrangements for species with broad or disjunct distributions, or species that are targeted by different gears in different areas or habitats. For example, current SESSF management arrangements do not consider stock structure in Blue-eye Trevalla, although it ranges from WA to Queensland and beyond Australian waters, and preliminary analysis showed some evidence for separate stocks between the SESSF and ECDW seamounts. There is an immediate need to develop and incorporate new spatially-based arrangements into management of Blue-eye Trevalla in response to complex spatial patterns in the fishery that include a change of fishing methods through time, whale interactions increasing in some areas, re-location of effort into underutilized locations (e.g. ECDF seamounts), and the series of recent and planned area closures that include Commonwealth Marine Reserves (CMR) in the GAB, off the eastern seaboard and on the offshore Tasmantid Seamount Chain, and fishery closures being implemented by AFMA and NSW Fisheries to project Harrisson’s and Southern Dogfish. There is a more general need to assess options for managing separate stocks of other species – such as regionalising TAC’s – and to evaluate options against EBFM performance measures that include economic and environmental indicators.

The last 25 years have seen a 3.5 fold increase in the population size of New Zealand fur seals (NZFS) in SA, which now number over 85,000 individuals. This recovery may continue for a further 15-30 years, and the level at which populations may stabilise is unknown. New haul-out sites and breeding colonies are establishing across the State, some in close proximity to finfish aquaculture, and major commercial and recreational fishing areas. In addition, an Australian fur seal population has recently established in SA and has more than doubled in the last five years. There is also growing concern from the seafood and ecotourism (little penguins, giant cuttlefish) industries and the community that fur seals are overabundant and that their populations and impacts need to be managed. As a consequence of this broad industry and public concern, this project was listed as one of the priority areas for investment by the SAFRAB.

Most of the seals that interact with fisheries, aquaculture and ecotourism are juvenile and sub-adult males that restrict their feeding the shelf waters; however the diet and foraging behaviour of this part of the population is poorly understood. Little is also understood about the potential competitive interactions between the three species of seals that may be limiting the recovery of the threatened Australian sea lion. The project aims to investigate the diets and foraging distributions of seals in SA’s gulf and shelf waters to assess the importance of commercial fish and finfish aquaculture species in their diet. Trophic modelling will be used to assess the impact of consumption on current and future seafood production, and industry questionnaires and consultation will be used to assess the economic impact and the degree and nature of interactions between seals and finfish aquaculture, fisheries and marine ecotourism industries.