Research to support the development of a Tasmanian Sardine Fishery
Developing a cost-effective monitoring regime and stock assessment for Sand Flathead in Tasmania
Sand Flathead account for well over half of the total catch (by numbers) taken by marine recreational fishers in Tasmania and represent the mainstay of Tasmania's recreational fishery. Furthermore, since the recreational catch of sand flathead is more than 20 times the commercial catch, trends in commercial catch and catch rates are of little value in inferring changes in stock status. This has meant that fishery independent or novel assessment methods are required. To date, IMAS has implemented a research program focused on sand flathead in the south-east of the state that provides a spatially restricted, perspective and semi-quantitative evaluation of stock condition. Given the significance of the species and a status of 'depleting' in the latest stock assessment report, there is a need to implement a more comprehensive stock monitoring approach throughout the state that can support the development of a spatially explicit quantitative stock assessment model. There is also a need to determine the appropriate spatial resolution to apply to the stock assessment model. As such, there is a need to understand the extent of adult movement and ontogenetic connectivity of regional sub-populations of sand flathead throughout Tasmania. In addition, by collation of biological data sets from historical studies and surveys conducted around Tasmania the extent and direction of potential changes in population size structures, and life history characteristics will be investigated. Where possible collated biological data will be used to assess spatial and temporal changes in life history characteristics to assess the implications of selective excessive fishing pressure and/or past and future climate change effects for this species.
Fisheries biology of short-spined sea urchins (Heliocidaris erythrogramma) in Tasmania: supporting a profitable harvest and appropriate management
Urchins have been fished in Tasmania since the 1980s, yet no significant research since a basic morphological description of the reproductive cycle in the 1970s has been conducted to support fisheries management. Spatial and habitat variability in urchin growth rates, maximum sizes and size at maturity across key harvesting regions are unknown.
There is a need to understand the drivers of seasonal and spatial variability in roe quality to maximise returns of ‘A-grade’ roe in order to maximise industry probability. Variability in urchin roe coupled with competitive catch limits is leading to localised concentration in effort and subsequently catch caps being reached or areas being heavily exploited before roe has reached its highest quality or optimal recovery. This is decreasing product value and fishery profits.
The lack of information on the biology, population structure and roe characteristics of the urchin not only continues to hinder the value of the wild fishery in Tasmania but also the capacity to manage it.
There are regions where high concentrations of barren forming urchins are present and are not targeted by the wild fishery due to poor roe quality. Trials of Norwegian technologies to enhance roe quality of these urchins are being planned as a part of international trials. Gonad (roe) development and waste generation need be assessed in order to manage the developing industry, as well as to optimise feed-regimes ahead of moving to full commercialisation. Successful urchin farming will facilitate the expansion of the urchin industry, allow for diversification in the oyster industry given recent outbreaks of POMS and assist salmon growers move into IMTA practices.
There is strong support from managers and industry for the proposed research that will guide the future profitability of the fishery and inform its management. The TasRAC has identified this as a high priority project. DPIPWE is bound by the Living Marine Resources Management Act 1995 to ensure that fisheries are managed in a sustainable manner. However, the Department has had to adopted a precautionary approach in management due to the lack of scientific knowledge on the species.
Can spatial fishery-dependent data be used to determine abalone stock status in a spatially structured fishery?
With the advent of the Status of Australian Fish Stocks (SAFS) process, there is now a requirement to provide a stock ‘status’ determination in addition to the annual TACC determination. The ‘status’ reflects changes in the overall biomass, the fishing mortality, or in their proxies. This has led to disagreements among researchers, managers and industry, largely due to uncertainty around how best to derive a meaningful overall stock status indicator to meet the requirements of the SAFS reporting process. These higher-level reporting processes are an important demonstration of sustainable management of Australian fisheries, but only if stock status determinations are accurate and defensible.
Australian abalone fisheries primarily use harvest control rules based around CPUE (Kg/Hr) to set TACC. However, with abalone, stable catch-rates may not indicate stable biomass and/or stable density. Catch-rates are frequently criticised because the effort needed to take a quantity of catch may be influenced by density but also by density independent factors such as conditions at the time of fishing, experience, and the ability of fishers to adjust their fishing strategy to maintain catch rates (diver behaviour driven hyper-stability). While there are many issues with the assumption that CPUE is a reliable proxy for abundance, it is assumed to be so despite the absence of robust data to validate use of CPUE in this way. In some jurisdictions CPUE is supplemented by sparse fishery-dependent size and density data. There is an urgent need to review common assumptions, methods and interpretations of CPUE as a primary indicator, and to determine whether inclusion of spatial fishery data could provide a ‘global’ indicator of stock status for abalone fisheries.