ELFSim

by Annabel Jones, Bruce Mapstone and Campbell Davies

The Effects of Line Fishing (ELF) Project aims to bring together information on all aspects of the Queensland Reef Line Fishery including fish biology, fisheries science and characteristics of the fishing fleets. The broad scope of research interests incorporated in the ELF Project will ensure the outcomes will encompass many different aspects of the fishery.

One of the principal outcomes from the ELF Project is to make the job of managing the Queensland Reef Line Fishery easier, with the development of an advanced computer 'simulator'. The simulator - termed ELFSim by its creators, ELF research scientists and computer modellers from CSIRO, simulates a virtual reef line fishery. It uses all the information gathered from the ELF Project, as well as other fisheries research and information from the fishers themselves. Just like a flight simulator, ELFSim can 'test run' several management options and highlight the positive and negative aspects of each.

Management advisory committee & stakeholder involvement

The Reef Line Fishery Management Advisory Committee (ReefMAC) is one group for whom ELFSim will be very useful. ReefMAC is comprised of representatives from each of the relevant stakeholder groups and has a crucial role in the management of Queensland fisheries by providing expert advice to the Queensland Department of Primary Industries and Fisheries. Part of the role of ReefMAC is to determine what regulations will be needed to steer the fishery into the future as a healthy, viable resource. This raises numerous questions. Are the current regulations sufficient? Would something else work better? Are further controls needed and what should they be? ELFSim will help to answer these questions.

ReefMAC and other stakeholder representatives, including fishers from all sectors of the fishery, conservationists and managers, have had major input into the development of ELFSim. These stakeholders have been directing the scientists on what sort of questions they wish to ask ELFSim, and how they would like the results to be presented. Their assistance will ensure ELFSim has maximum value for management of the Queensland Reef Line Fishery.

ELFSim components & expected outcomes

The ELFSim model is based on three main components, to account for fish biology, dynamics of the fishery and fisheries management.

The biological component takes into account everything we know about fish biology including growth, reproduction and mortality. Currently this model is tuned only to coral trout, which are the predominant target species of the fishery, but it will be extended to include other species in the future.

The fisheries dynamics component considers how fishers' activities may change: for instance where they fish, how much they fish etc. In the future we will also build in influences on fishing activity such as weather and changing market prices.

The fisheries management component will include information on management constraints that might be placed on fishers, such as limits on catch or effort by introduction of closed areas, closed seasons etc. This is the area where new management options can be tested. How these components interact with each other and the ELF Project is shown in Figure 1.

Figure 1: ELFSim and how it interacts with stakeholders and the ELF Project

ELFSim also incorporates uncertainties about the fishery, such as changes in rates of recruitment from year-to-year and reef-to-reef, and variation in catchability of fish from time to time and on different reefs. Considering these uncertainties means ELFSim will provide a different answer for every scenario each time it runs. Using the flight simulator analogy, you may end up on a slightly different approach to the airport each time you get behind the controls, due to different weather conditions etc. However, if you take the average result from a 1,000 'flights' you can identify where you are most likely to end up. Together with the average results, ELFSim also gives information about the range of results from all of the runs. This gives you an idea of the risk that each scenario tested with ELFSim might not meet the desired objectives for the fishery.

ReefMAC and others involved in fisheries management in Queensland will be putting ELFSim to the test. An example of a question that could be asked of the model is: Two hypothetical options for fisheries regulation have been put to an advisory group as suggested strategies to maintain the fish stocks at an acceptable level. These might be:

Option 1: Reduce fishing effort by 30%

Option 2: Introduce spawning closures

ELFSim would run each scenario hundreds of times, and collate the number of times the virtual fish stocks fall below a specified desirable level. These figures would describe the likely risk that each strategy would fail to meet the stated objective for the fishery. The results would be presented in a table clearly highlighting the pros and cons of each option and the risk associated with each. It won't provide a definitive answer (or ‘magic number'), but it will clearly identify the trade-off between these two options and thus will provide valuable information to all the decision makers. They can then make an informed decision on which option is likely to work best to ensure a healthy fishery in the future.