The Southern and Eastern Scalefish and Shark Fishery (SESSF) is a Commonwealth-managed, multi-species, multi-gear fishery, operating under a comprehensive Harvest Strategy. It targets over 80 commercially valuable species across inshore, offshore, and seamount areas, utilising diverse methods including demersal trawling, Danish seining, gillnetting, line fishing, and traps. Management employs a combination of quota systems and input controls, such as spatial closures, gear restrictions and limited entry. A formal Harvest Strategy Framework (HSF), established and adopted in 2005 (Smith and Smith 2005), guides fishery monitoring, stock assessment, and the determination of Recommended Biological Catch’s (RBCs) through a tiered stock assessment system. Stock assessments range from simple trend analyses (Tier 4) to complex quantitative models (Tier 1), depending on data availability.

The SESSF is an amalgamation of four previous fisheries – the South East Trawl and Non-Trawl Fisheries, the Southern Shark Fishery, and the Great Australian Bight Fishery. Each sector of the SESSF can be defined based on location, gear and target species. The set of committees that undertakes assessment of key stocks, and also deals with broader ecological impacts of fishing, now comprises: SESSF Resource Assessment Group (SESSFRAG), South East Resource Assessment Group (SE RAG), Shark Resource Assessment Group (Shark RAG), and Great Australian Bight Resource Assessment Group (GAB RAG). Each of the assessment groups (South East, Shark, GAB) is responsible for undertaking stock assessments for a suite of key species, with the timing of assessments coordinated by SESSFRAG.

The formal adoption of a HSF for the SESSF was mandated following the introduction of environmental legislation across federally-managed fisheries (Environment Protection and Biodiversity Conservation Act 1999) (EPBC Act, 1999). Although development began in 2005, initial performance testing occurred post-implementation (Wayte, 2009). The HSF has been adapted over time to respond to changes in the fishery, new stock assessment approaches, to reduce the frequency/cost of species-specific stock assessments, and to reflect policy changes. While some modifications have been evaluated (e.g., marine closures, initial multi-species harvest strategy; Tuck et al., 2017; Little et al., 2025), several aspects remain untested.

Climate-driven reductions in stock productivity is having a marked impact on the stock status of some species. This can lead to considerable management challenges with implications of an effectively changing unfished biomass and the consequence of this on reference points (Bessell-Browne et al., 2024). Evidence indicates that environmental shifts and subsequent ecosystem changes have contributed to the non-recovery of several shelf stocks, including Eastern Redfish, Blue Warehou, Eastern Gemfish, and Jackass Morwong. The inherent complexity of multi-species fisheries management and the prevalence of climate-driven changes across the fishery requires the development and evaluation of novel approaches.

Through a consultative process, this project will design harvest strategies for the SESSF and test their robustness using Management Strategy Evaluation (MSE). The harvest strategies to be tested will likely combine existing elements (such as the tiered assessment approach) and new elements arising from the first multi-species harvest strategy project such as indicator species and triggers, and from further consideration throughout the project and at the proposed workshops (e.g. see ‘métier-based assessment and management’ below).
The project will recognise that the SESSF is a complex fishery that spans multiple sectors (from deep, slope, shelf waters; across sharks, crustaceans and scalefish; and applies multiple gear types). The Commonwealth Trawl Sector (CTS) targeting Tiger Flathead on the shelf exemplifies the challenges associated with managing multi-species fisheries in a cost-constrained and climate-driven environment. There is a high level of bycatch, including vulnerable ‘choke’ species, and the cost of monitoring and assessments is high relative to the value of the fishery. The focus of this project, in the first instance, will be on the more highly structured and complex shelf stocks. The types of harvest strategies developed, and subsequent robustness testing across various scenarios (climate, data sampling regimes, closures), for the shelf stocks will be given due consideration with regard to their suitability for other sectors of the SESSF, both during initial design and potential implementation.

For example, the technical interaction between gummy and school shark is well known. It is anticipated that testing on shelf stocks of the impacts of new harvest strategies will be applicable to school shark, as a choke species, and gummy shark. Likewise, the utility of multi-year TACs and subsequent buffers (reductions in TACs to account for increased uncertainty) will be transferable to other SESSF stocks, and indeed other fisheries.

The project does not assume that a single harvest strategy will be suitable across all sectors. Instead, it aims to develop a suite of conceptual strategies, beginning with a focus on the more structured CTS. While some strategies may prove broadly applicable, others will require sector-specific adaptation. For sectors targeting Orange Roughy and Blue Grenadier, where current strategies are already effective, minimal change is anticipated. The broader applicability of CTS-based strategies will be explicitly evaluated—based on sector complexity, data availability, and the capacity of tools like ATLANTIS and RATPACK to support cross-sector MSE testing, rather than assumed.

This project aims to explore practical, implementable, and cost-effective harvest strategies that meet the intent of the new CHSP. It also has strategic applicability beyond the SESSF.

Note, a separate project is underway to develop harvest control rules when no relative index of abundance is available (e.g. Close-kin Mark-recapture). Operationalisation of this approach, including CKMR, will be considered as part of this project, subject to the outcomes of that work.

What This Project Will Not Deliver

The project will not extend to implementation of the harvest strategy. This will be the responsibility of the management agency, AFMA, following the completion of the project. It will not replace all existing harvest strategy elements. Instead, it will evaluate and integrate components where appropriate, while maintaining continuity with proven practices. The project will not fully operationalize complementary work being conducted in parallel, such as the development of harvest control rules for data-poor stocks without abundance indices. While integration may be considered, this work is outside the primary scope. It is not intended to be a one-size-fits-all solution. While adaptable, the strategy will require tailoring to suit the specific needs and contexts of other fisheries or jurisdictions.