The recently-completed National Recreational and Indigenous Fishing Survey (NRIFS) estimated that more than 11 million bream and pink snapper (comprising over 10% of the total released catch) were caught and released from recreational hook-and-line fisheries during 2000/01 (Henry and Lyle 2003). These rates of discarding are of considerable concern, because they have the potential to represent high levels of previously unaccounted fishing mortalities.

In order for Australia’s commercial and recreational hook-and-line fisheries to be considered ecologically sustainable, their fishing operations should minimize the mortality of discarded fish. The release of large numbers of fish from commercial and recreational fisheries whose fate is currently unknown is, therefore, of major concern to all stakeholders in these fisheries. The review by McLeay et al. (2002) prioritised breams and snappers as two species potentially susceptible to high levels of mortality after release from hoon-and-line fisheries in Australian. Further, hook damage and handling (e.g. exposure to air, physical damage, etc ) were identified as factors that probably contribute the most towards these mortalities.

The regulation of fishing mortality in all Australian hook-and-line fisheries is mostly based on legal lengths and daily bag limits on the assumption that the majority of discarded fish survive. The almost complete absence of information on survival rates for the majority of species precludes any validation of the benefits of current management options or the effects of proposed changes. For example, in Victoria during the late 1990’s, the minimum legal length (MLL) for black bream was increased to conserve fish stocks in the Gippsland Lakes. While this has resulted in larger fish being retained by anglers, recent creel surveys in the Gippsland Lakes showed that up to 80% of the black bream catch is below legal size and therefore discarded (Conron and Bills, 2000). If the PRS of these discarded bream is low, then the increased MLL will achieve little in terms of conserving stocks. Similarly, Victorian fisheries managers will be reviewing the MLL for pink snapper which, at 27 cm total length (TL), is low compared to other States and which per-recruit analyses suggest is less than optimal for maximising yield (Coutin, 1997). Knowledge of the PRS rates of pink snapper is critical for evaluating the benefits of any change to the current MLL.

There is a perception among all stakeholders (including recreational and commercial fishers, tourism organisations, conservationists and Fisheries Managers) and evidence from related studies (McLeay et al., 2002) that many fish released after capture by current hook-and-line methods may die. Despite these widespread concerns, there are very few scientific data available on the actual PRS rates for line-caught fish in sheltered temperate ecosystems in Australia. There is a clear need to do this research for the key species identified, and to assess the significance of any mortalities on their populations. If the levels of PRS are of concern then there is a consequent need to (i) identify the deleterious hooking, handling and release procedures, (ii) examine ways to improve PRS, and (iii) incorporate realistic estimates of PRS into fishery and stock assessments.

The FRDC-funded review of this issue in Australia highlighted the need to coordinate research projects and to develop a standardised system for classifying stress, condition and injury and the stressors applied during catch-and-release procedures. By expanding and refining the field based experiment undertaken as part the pilot project funded by the Victorian FRAC, this proposed project would be taking an important step towards addressing these needs. It would also allow recommendations for the appropriate types of hooks and handling protocols to be used and ensure the protection of large numbers of discarded fish caught in sheltered temperate ecosystems. Further, as a demonstration of how these sorts of field-based, fishing-impact studies should be designed, analysed and interpreted, the proposed project will help develop standardized methodologies for estimating PRS and evaluating its impact on fish stocks.