Reefs represent important habitats for commercially and recreationally exploited species under Tasmanian jurisdiction. In Tasmania, shallow reefs (25 m) are significant to commercial and recreational fisheries for scalefish and invertebrates. These include live-fish fisheries for banded morwong (gillnet) and wrasse (trap and line), as well as recreational and commercial gillnet fisheries for species such as bastard trumpeter, striped trumpeter and blue warehou. Other species including jackass morwong, various leatherjackets and boarfish, are also relatively commonly caught on shallow inshore reefs. Most of these species also occur at greater depths but as only striped trumpeter are subjected to a targeted (line) deepwater fishery; deep reefs are therefore assumed to be important refuges from fishing pressure. While recent research has improved our understanding of the population biology of some of these species, management of these fisheries is primarily based on characteristics observed from shallow reefs. The lack of quantitative information on the significance of deep reef habitats as refuges and/or their role in population structuring limits our ability to undertake informed risk assessments of the impacts of current fishing practices and evaluate alternative management options.

While the structure, composition and functioning of shallow-reefs (10m) and their associated fish communities has been studied extensively, the ecological importance of deeper reef ecosystems has not been investigated apart from recent baseline studies of offshore Commonwealth MPAs. Linkages and associations between fish communities in shallow and deeper reef areas remain a distinct knowledge gap.

Commercial and recreational fishers are permitted to use gillnets in Tasmania. There are several classes of gillnet distinguished by mesh size - commercial gillnets include, small mesh, graball and shark nets, while recreational gillnets include mullet and graball nets. During the past 5 years around 150 commercial operators each year have reported gillnet use, for an average catch of 200 tonnes of scalefish. Recent information for the recreational sector is limited though recreational netting remains popular, with over 10,000 net licences issued in 2009. Previous surveys indicate that recreational fishers target much the same species as commercial operators.

Over the past decade there have been several management initiatives, including a prohibition on night netting for most areas and, more recently, the introduction of maximum soak times. These initiatives have been designed to improve gillnetting practices, and reduce wastage and impacts on non-target species. Despite this, there have been conspicuous declines in the abundance of several key gillnet species along with increasing community concern about the ecological impacts of gillnetting. This concern has been particularly evident in the debate surrounding the introduction of marine protected areas, with gillnetting identified as a key threat to biodiversity. Furthermore, in the 2009 Scalefish Fishery review DPIPWE identified the need to develop strategic policy in relation to no-netting areas to address issues including resource sharing, wildlife interactions and stock management.

In view of the above, there is an urgent need to better understand how recent management initiatives have influenced netting practices, and to objectively assess the risks and impacts on target and non-target species. Ultimately such an understanding will be pivotal in informing the on-going debate over the future management of gillnetting in Tasmania.

The development of live fish markets in the early 1990s has created a strong demand for temperate reef species, specifically banded morwong and wrasse. Prior to these developments these species had little commercial value, often being used as bait for rock lobster. This demand has resulted in major increases in fishing pressure directed at the reef fish communities and while there has been much work on tropical species, our knowledge of how temperate reef species respond to fishing pressure is comparatively poor.

Although banded morwong and wrasse have vastly different life history characteristics (early life history, reproductive strategies and age and growth), they are basically sedentary, exhibiting population structuring at a small spatial scale. However, related to the general mis-match between the spatial scales of fishery management, fishing operations and fish population structure, there is considerable potential for localised depletion, and hence for serial depletion of the resources.

In Tasmania, steady declines in catch and catch rates have led to concerns that fishing has already significantly impacted banded morwong stocks. In Victoria, a more controlled approach to the development of the fishery has been taken, with an initial three-year developmental phase to be followed by a review to ascertain long-term sustainability.

Although key fishery indicators, catches and catch rates (analysed at state-wide or regional scales) have remained relatively stable for wrasse, there are anecdotal reports of localised depletions from Tasmania. Furthermore, the selective removal of adult male blue-throat wrasse has the potential to impact significantly on egg production even if female spawner biomass is adequate.

There is therefore an urgent need to develop robust stock assessments, appropriate performance indicators and monitoring strategies for these species if they are to be managed sustainably. However, being small-scale fisheries based on sedentary, spatially structured populations, an innovative approach to fishery and biological monitoring and data analyses is required. Since Tasmanian, Victorian and South Australian fisheries share many common characteristics there are considerable benefits from a coordinated approach to this issue. This study will also have broader implications for other small-scale and data poor fisheries.