Using GPS technology to improve fishery dependent data collection in abalone fisheries
Strategic R&D Plans
TasFRAB 2005 Theme 3: Improving the scale of data collection and development of performance measures.
Tasmanian Abalone Strategic Research Plan (2005 – 2009) - Need for fine-scale data on fishing effort.
Catch and effort data are either important components of model-based stock assessment (NSW, VIC, SA, NZ) or form the primary basis for trend-based stock assessment (TAS). Because of the current low quality and resolution of effort reporting in abalone fisheries, CPUE data are insensitive to serial depletion. Low resolution catch effort data decreases the ability to identify stock declines, and increases the risk that stocks will collapse, or be diminished for long periods. Low resolution data will also increase the risk that major management intervention is required because of late confirmation a fishery is in decline.
Acquisition of fine-scale data on fishing location is an essential component of flexible management for abalone fisheries, and provides managers and industry with the capacity to continue broad scale management at larger scales (zones), but also to manage elements of the fishery at a fine scale if required. A flexible scale of management will enable the current natural dynamic of fishing effort within regions to continue.
CPUE is the primary fishery dependent indicator variable that is used to measure performance. Because CPUE is not linearly related to stock abundance, there is an important need for alternate indicator variables. This need could be resolved through the development of new technology derived indicator variables that can be calculated using the combined GPS and DTR data.
High resolution location and effort data based on GPS/DTR data will increase the precision of stock assessments by improving quality of CPUE data, and by development of additional indicator variables.
Final report
Implementation of fishery independent surveys for the Southern and Eastern Scalefish and Shark Fishery
Catch and effort data obtained from commercial logbooks is the primary source of information used as an index of abundance for most SESSF species. The assumption underlying this is that commercial catch rates change in a linear fashion with abundance. This assumption, however, has little independent support for many SEF species and is frequently criticised by industry and scientists alike. One of the most significant problems with commercial CPUE data in the SEF is that fishers modify their fishing practices to suit quota availability and market demands. Also, many fishermen only put the retained catch in logbook data, not the total catch. Furthermore, the influence of environmental conditions on fish availability also reduces the effectiveness of CPUE as an index of abundance. Low or bycatch TACs also prevent catch rate data being used as an index of abundance.
Implementation of a fishery independent survey is the most cost-effective and feasible means to get an independent index of abundance for the suite of SESSF species.
Recognising this, the SESS Fishery Assessment Group (SESSFAG) has placed highest priority on the need to implement fishery-independent methods for surveying relative abundance of SESSF fish stocks.