Target species of Tasmanian scalefish fisheries (TSF) remain difficult to assess and manage due to the wide range of species (> 20 species) and variety of both commercial and recreational fisheries methods. TSF are currently assessed using commercial catch and effort data as well as age and length information. However, some key TSF species landings are increasingly greater in the recreational sector, with a comparatively low commercial catch. Therefore, due to the absence of regular and robust CPUE data, innovative fishery independent data collection programs are required to routinely monitor TSF species and provide adequate data for stock assessment models. This project will review and collate data from previous studies to design and test strategic and cost-effective novel fishery-independent survey methods that collect population dynamics data for a suite of key scalefish fisheries species, across both environmental and fishing intensity gradients in Tasmania. Outcomes will improve stock assessment methods by providing new and additional data for data-poor and undefined species, and, if proven cost-effective, establish an ongoing, long-term fishery-independent monitoring program to enhance the sustainability of TSF. We will collate historical data on Tasmanian scalefish abundance, biomass, distribution, and length-frequencies collected in previous research projects and collect and compare new data to fill current knowledge gaps about localised population depletion and population dynamics across different habitats. Many of the popular commercial and recreational scalefish fisheries are increasingly of concern, with southern sand flathead, southern garfish, and bastard and striped trumpeters all assessed as depleted in the most recent (2020/21) Tasmanian stock assessment (Fraser et al 2022), while others (such as flounder - Pleuronectidae family, longsnout boarfish, and barracouta) were assessed as undefined due to lack of available data for these species. Our results will better inform data-poor stock assessment approaches and will have implications for fisheries managers making critical management decisions for depleted, depleting, and undefined Tasmanian scalefish fisheries species.
Project number: 2023-002
Budget expenditure: $370,386.00
Principal Investigator: Alyssa Marshell
Organisation: University of Tasmania (UTAS)
Project start/end date: 31 Dec 2023 - 9 Jan 2027
1. Determine the benefits and limitations of alternative stereo-video methods to collect image-based fish size estimates, including assessing the effectiveness of length-monitoring to inform assessments of depleted/depleting and undefined commercial scalefish species.
2. Investigate image processing software for the implementation of a fully automated system for post-processing of stereo-video surveys using artificial intelligence and machine learning.
3. Compare length-frequencies of key scalefish species from fishery-dependent and independent survey datasets and length-based stock assessment methods.
4. Investigate novel sampling methods to collect length data of key scalefish species.
5. Conduct a comprehensive cost-benefit analyses of traditional versus novel monitoring methods, including power to ensure the feasibility of implementing and incorporating novel methods into regular fisheries-independent monitoring and assessment outcomes.
6. Investigate the role of incorporating citizen science and include recreational fishers’ engagement in supporting cost-effective and novel fisheries-independent monitoring programs.