Development of a temperature monitoring framework for Tasmania's seafood industry during marine heatwaves

Marine heatwaves can have devastating impacts on marine ecosystems, with a strong El Nino event forecast in Australia for the summer/autumn of 2023-24. Forecasts by CSIRO indicated sustained increases in water temperatures down the east coast of Tasmania with potential to significantly affect fisheries, aquaculture, and marine habitat. While sea surface temperature (SST) outputs from Bureau of Meteorology (BOM) and National Oceanic and Atmospheric Administration (NOAA) can provide information regarding broadscale patterns, missing is fine-scale, near-coastal and below surface information that is highly relevant to fisheries, aquaculture and marine coastal environments. This project aimed to develop methods of collecting data at a scale and in locations that are relevant to fisheries in Tasmania. Methods were developed for both the deployment of instrumentation on fishing gear, along with R routines for efficiently and effectively presenting and reporting on the data. HOBO temperature loggers were deployed on commercial fishing gear from February to May 2024 to collect fine scale temperature data. Industries included the commercial Southern Rock Lobster, octopus and scalefish fisheries. Once the data was collected, it was cleaned and complied and used to compare to SST outputs for marine heatwave (MHW) monitoring. Temperature data was collected across the state for the period from February to May 2024. Outputs in the form of letters containing the data they collected where provided back to participant fishers. This included a map of where the loggers were deployed, a per deployment temperature summary, the in-water temperature profile compared to seasonal averages and thresholds and overlapped on MHW classification plots. In addition, all data collected was developed into a spatially aggregated temporal summary to visualise the scope of data collected during the project. These methods will be an essential tool for the management of fisheries in future MHW events, allowing for the tracking of temperature through the seafood supply chain and providing the framework to compile spatially and temporally robust datasets. End users of this data will be industry, researchers and government looking to better understand and manage MHW conditions as they become increasingly common into the future. Monitoring temperature through deployments with commercial operators will help to improve decision making for fishing locations, give marine farming better preparation around stock flows and allow for strategic decisions to be taken to adapt to changing environmental conditions. Overall, the method developed through this project fills an identified gap at a local level, which allows fishers to monitor temperature at industry-relevant and at a spatial scale that is indicative of fishing activities. Should this method be used in the future there are a number of further R&D activities that could be explored. This include:
•An investment into loggers with a reduced time to environmental equilibrium
•Methods that will reduce the time-lag between capturing the data and providing the data to thefisher. These include:
oIncreasing efficiencies in data Quality Assurance/Quality Control (QAQC) and datacollation through further development of R scripts (i.e. reduction in time from weeks todays).
oA system that allows real-time or near real-time data collection from depth to becommunicated directly to the fisher (i.e. reduction in time from weeks to hours orminutes).
•Methods that will decrease burden on the fisher to collect location data.
•Real time temperature monitoring of boat wells to complete supply chain temperaturemonitoring
Beyond the development of this method, there are several broader areas of research that this activity has highlighted as being of value in pursuing to better safeguard Tasmania’s valuable marine industries from future, and likely more frequent, MHW events. Firstly, long term local data is needed to better inform industry and facilitate adaptive management by government. While SST estimates obtained from NOAA and NASA JPL satellite imagery are useful at understanding trends on a broadscale, our project highlighted the variability of these estimates with data collected from depth at local fishing grounds. This method allows for the collection of this data, which if continued in the long term, will aid fishers in making better decisions around fishing effort during MHW events and provide valuable data to ground-truth climate models at a local scale. There are numerous marine industries within Tasmania that collect temperature data, although a thorough assessment of what is collected where and when has not been undertaken. Understanding what is already being collected across Tasmania’s wild fisheries and aquaculture sectors could facilitate an industry-wide temperature data collation and collaboration framework during marine heatwave events. A system for sharing data between coastal industries could help to enable better response to MHW events across the Tasmanian seafood sector. This data may also be used to strengthen the capacity of predictive models and better understand the strengths and limitations of relying on broad-scale satellite data to inform decision making. Adoption of the method more widely across the fishing industry may also help understanding how MHW events may also affect the productivity of Tasmania’s marine ecosystem, beyond mass mortality. It is also an important part of an informed response. Shifts in productivity of coastal systems are more likely to cause subtle change over time; better understanding of how these changes may manifest are vital for ensuring a sustainable wild fisheries industry for future generations in the face of climate change.