Protection and management
• Improved integration is required between fisheries and ecosystem management and a better application of ecosystem-based fisheries management (Pikitch et al. 2004). For instance, a panel charged with reviewing the proposed new management arrangements for the ECIFF considered that more stringent measures could be put in place to account for the fact that this fishery is operating within a MPA in a World Heritage Area, and that arrangements to protect the sustainability of sharks were not sufficient. However, the new management arrangements included scope for a shark TAC of 600t, and for interactions with protected species (Gunn et al. 2008).
• It is recommended that the GBRMPA assess the viability of establishing a greater number and area of Pink (no-go) Zones on the GBR; recent work on a number of generalist top predators suggests a much better level of compliance in Pink Zones than Green (no-take) Zones. It is recommended that the GBRMPA investigate the viability, cost and logistics of enabling further legislative protection of predators, prioritising species for consideration according to this review’s risk assessment.
• Improved education is required on the importance of green zone compliance. Better enforcement and stricter penalties for infringing on green zones; current levels are not adequately deterring non-compliant fishers (Ayling & Choat 2008).
Research
The principal question concerning the role and importance of top predators on the GBR that remains unanswered is: “What will happen to the rest of the ecosystem if the top predators are, or have already been, removed?” The GBR offers a unique system in which to design a research program that seeks to answer this question. It is large, encompasses a variety of different habitats, exhibits a number of environmental and anthropogenic impact gradients and is subject to an existing zoning system that has resulted in areas that harbour predator communities at different densities. Specifically, long-term monitoring of no-go Pink Zones embedded within large no-take Green Zones may provide the best tool for understanding ecosystems where predator densities are most likely to be at ‘natural’ levels. A better understanding of the role of predators on the GBR requires research on the predators themselves, and also more ecosystem- level research.
• Effective censuses of the status and catch of those species prioritised through the risk assessment (especially those falling into the ‘extreme’ and ‘very high’ risk categories are an essential first step towards understanding the current status of the most important predators on the GBR. This would help to determine which species are undergoing the greatest decline, and assist in further prioritising limited resources for more detailed biological and ecological studies.
• Distribution, abundance and life-history data is required for many of the predator species. Some of this research is underway for some species, but it needs to be completed for all exploited GBR sharks as a priority. It is suggested that research on individual species be prioritised according to this review’s importance index and / or risk assessment. Research on individual species, particularly sharks, should include:
124 - Life history and habitat use information for all species, especially those caught
by fisheries and prioritising the most ‘at risk’;
- Logbooks and observer programs that distinguish between species as much as possible. Better effort and catch data for all species across all fisheries, with better and more regular reporting mechanisms;
- Records of how many sharks a year are taken as by-catch;
- Determine overall GBR exploitation rates of ‘at risk’ species including all fisheries and sectors, and deaths from other factors;
- Better understanding of post-release survival rates from all sectors, including charter;
- Develop a list of potential no-take species based on the least productive sharks caught by all fisheries. This will help identify where there is not enough knowledge to make a species ‘no-take’ and direct research on particular species.
• It is recommended that a targeted research program be developed to specifically undertake ecosystem-level comparisons between different zones, including reef and non-reef habitats. Factors to consider for such a research program include:
- Making use of large-scale latitudinal gradients and cross-shelf gradients in anthropogenic pressure;
- Incorporating gradients in fishing pressure within areas open to fishing;
- Incorporating zoning-related gradients in fishing pressure (long-term monitoring of no-go Pink Zones embedded within large no-take Green Zones may provide the best tool for understanding ecosystems where predator densities are most likely to be at ‘natural’ levels);
- Considering all the GBR’s major habitat types: coral reefs, inshore and inter- reef areas, pelagic and deep-water environments. Research has begun to target non-coral reef areas and a future program on the role of predators on the GBR will benefit from incorporating the expertise of researchers that are already examining these systems.
- Using current accepted sampling designs that allow sufficient replication at all levels, and that take into account sampling techniques relevant to the species and to the habitat (e.g. visual surveys are useful in clear water, while tagging studies and catch data may be more efficient in inshore turbid waters and remote techniques are suitable for deep water);
- Selecting a wide range of ecosystem response variables, including potential prey species, competitors, key functional groups such as herbivores, invertebrate feeders and macro-invertebrates, habitat structure and complexity, and the community composition of benthic organisms.