ESD risk assessment for under-utilised species to facilitate structural reform of South Australia's commercial Marine Scalefish Fishery
Building economics into fisheries management decision making - to utilise a suite of SA case studies
Isolating social and economic objectives within multiple stakeholder fisheries – a case study: the South Australian Marine Scalefish Fishery
Do commercial fishery data reflect stock status in South Australia's Southern Garfish fisheries?
Managing South Australia’s (SA) regional fisheries for southern garfish remains challenging and topical. For numerous decades the populations in the northern gulfs have sustained the most significant fisheries for this species. Furthermore, these fisheries have sustained extremely high levels of exploitation, which has resulted in the truncation of populations to a few age classes. This over-exploitation has been addressed through a ‘stock-recovery’ harvest strategy implemented in 2012 that is ultimately aimed at reducing the exploitation rate from 69% to 30% by 2020. However, the current assessments of the regional fisheries are based almost entirely on data from the commercial hauling net sector. Yet, the fished populations, i.e. those occupying inshore waters of 5 m depth in the northern gulfs represent only a small proportion of the distribution of southern garfish throughout the SA gulfs. As such, the characteristics of the garfish populations outside the fished areas, i.e. in the off-shore, northern waters and all southern waters, are currently poorly known. Furthermore, the extent to which recruitment from outside the fished areas contributes to the remarkable resilience and persistence of southern garfish populations to prolonged fishing pressure is also not understood.
Information on the relative abundance, population size and age structures and reproductive potential of southern garfish in unfished areas is needed to assess the status of SA's garfish stocks and to evaluate the suitability of indicators based on commercial fishery data for stock assessment. This information is also needed to understand the remarkable resilience of southern garfish to prolonged high fishing pressure.
Final report
Spatial management of garfish in SA - stock structure and adult movement
Knowledge of adult fish movement and stock structure is fundamental to identifying the appropriate spatial scale at which the processes of population replenishment work, and thus the spatial units to which fishery management should be applied. The management of the garfish fishery of South Australia has recently been at a heightened sensitivity due to serious concerns about the sustainability of the fishery. Yet, a comprehensive understanding of fundamental aspects of the life history and population biology of this species is lacking, which significantly impedes identifying the most appropriate spatial management structure. There is no understanding of the movement patterns of the adult fish, and the influence of that movement on the stock structure. Thus, it is not known the extent to which such movement helps sustain different regional populations and the extent to which these are independent and discrete. There is a need to rectify this lack of knowledge and understanding for southern sea garfish, so that management of the South Australian fishery can be applied at the appropriate spatial scale and spatial management units.
Final report
Development of a fisheries habitat suitability model utilising a geographic information system
The FRDC Review of Fisheries Habitats stated that “we must know where and what must be conserved for sustainability of fisheries and mariculture, before we determine why and how to do it”. At present key uncertainties exist concerning both the relative values of fisheries habitats and the effects of human disturbances at both regional and local scales. As a result, the FRDC Review found that strategic R&D is needed to overcome the poor ability to predict and manage such disturbances. Specifically, the collection, interrogation and extension of new and existing fisheries and habitat data at scales useful to management are required.
While it is generally known which habitats fish are found in association with, the critical factors which govern fish-habitat usage are poorly understood. In the absence of knowledge about why fish are utilising specific habitats, techniques are required to provide managers with information about the relative importance of different habitats and an ability to predict the impact of different pressures on these habitats. A Habitat Suitability Modelling approach is an effective means that can be employed to enable fisheries managers to identify the spatial component of fish-habitat links and make informed decisions on the management of habitats.