Modelling multi species targeting of fishing effort in the Queensland Coral Reef Finfish Fishery
James Cook University (JCU)
The Coral Reef Fin Fish Fishery (CRFF) is a multi-species line fishery. Until recently there have been substantial gaps in our knowledge of the biology of even the major target species of the line fishery and considerable uncertainty about the impacts of current levels of fishing on the harvested stocks. The CRC Reef Effects of Line Fishing (ELF) Project has provided an improved understanding of: i) the biology of the major target (coral trout and the red throat emperor) and by-product species (stripey bass, moari wrasse, barramundi cod, lesser serranid spp, etc) and, ii) the characteristics and fishing practices of the different sectors of the fishery. One of the main tools for delivery of the outcomes of the ELF Project is ELFSIM, a set of simulation models that will be used to evaluate alternative management strategies against specific objectives for common coral trout. Given the multi-species nature of the CRFFF, there is a need to address the implications for the effectiveness of alternative management strategies of fishers harvesting different species, with divergent distributions and biology, either by targeting or as a significant by-product when targeting other species. This is especially relevant on GBR where many species have different spatial distributions and area closures are a prominent management strategy that directly affects the distribution of fishing effort. An example of a potential management strategy that includes criteria for which coral trout and red throat emperor differ substantially is the proposed spawning closures currently being considered by REEFMAC. The proposed closures target the peak spawning period for common coral trout (October-November). This period does not, however, include the majority of the spawning season for red throat emperor (July-September). The potential effects of the closures, if implemented, on the harvest of either species, the spatial distribution of effort and impact on the fish stocks are unknown. The models proposed in this task will provide a formal context in which to examine the range of potential responses. Previously our capacity to address the multi-species nature of the fishery was limited by a paucity of information (for target species and fishing practices) and lack of a formal framework (management strategy evaluation (MSE)) to do so. This project is a strategic requirement to explicitly incorporate the multi-species nature of the CRFF in the evaluation of alternative management strategies for line fishing on the GBR. While this project focusses on the CRFF, the tools developed will provide the basis for extension to include other species of the line fishery or application to other fisheries. This project directly addresses QFIRAC objectives 1.8, 3.2, 3.4, 3.5 & 5.4 and ReefMAC’s and GBRMPA's concern for management of the diversity of impacts of the line fishery on species other than coral trout.
1. Document the decision-making processes that influence effort distribtuion of GBR line fishers in response to varying amounts of catch of target and non-target species and characterise the factors that result in changes in targeting behaviour by GBR line fishers.
2. Develop computer simulation models that predict the spatial distribution of effort by commercial line fishers in response to changing levels of catch of target and non-target species in the Queensland Coral Reef Fin Fish Fishery.
3. Formally evaluate alternative harvest and conservation management strategies for coral trout and red throat emperor for the Queensland Coral Reef Fin Fish Fishery, given models of changes in fishing strategy related to the harvest of multiple species, either through target switching or retention of significant by-product.