Title:

Forecasting spatial distribution of Southern Bluefin Tuna habitat in the Great Australian Bight – updating and improving habitat and forecast models

Project Number:

2018-194

Organisation:

CSIRO Oceans and Atmosphere Hobart

Principal Investigator:

Paige Eveson

Project Status:

Current

FRDC Expenditure:

$90,000.00

Program(s):

Environment, Industry

Need

This project is needed to continue supporting improved operational planning in the SBT purse-seine fishery for ranching operations in direct response to observed changes in fish distribution over the past 7 years. A habitat forecast system was developed as part of FRDC Project No. 2012/239 to deliver forecasts of suitable SBT habitat up to two months in future, and these forecasts have proven highly useful to industry to aid in their decision-making and planning of fishing operations. Unfortunately, the seasonal climate model currently being used to produce the habitat forecasts (POAMA) has been superseded by a new model (ACCESS-S), with POAMA scheduled to be decommissioned in 2019. This project will undertake the necessary migration of the current habitat forecasts to run using ACCESS-S. This will not only keep the forecast delivery website operational, but will also mean that a higher resolution, state-of-the-art forecasting model is being used (details of ACCESS-S and a system comparison with POAMA can be found at http://poama.bom.gov.au/general/access-s.html). Importantly, this project will also evaluate the skill of ACCESS-S forecasts in the GAB for the variable(s) of interest (currently sea surface temperature, SST). SST forecasts produced by POAMA were found to have useful skill in the GAB up to two months into the future during the months of interest, this needs to be assessed for ACCESS-S. In addition, as part of this project, the habitat preference models will be updated using new archival tag data to determine whether SBT preferences have changed. As noted in the proposal for FRDC Project No. 2012/239, continual updates are essential to ensure the habitat forecasts remain relevant, particularly in the face of climate change and possible changes in fish behaviour in response to a wider distribution of warm waters. Furthermore, all available archival tag data will be used to evaluate if there are size-specific differences in habitat preferences of tuna in the GAB. This is a real need for industry now that SBT juvenile populations are increasing and the GAB is suitable for a wide range of age-classes.

Objectives

1. Update SBT habitat preference models for the GAB using additional new archival tag data

2. Investigate potential of age-specific habitat preference models

3. Provide “now-casts” (i.e., real-time predictions) of areas of suitable SBT habitat based on updated habitat preference models (note that the habitat model currently in use is based only on SST)

4. Obtain fortnightly to monthly SST forecasts from the BoM’s new seasonal climate forecasting model ACCESS-S, and assess skill of these forecasts

5. Produce updated fortnightly to monthly higher resolution forecasts of SBT habitat distribution in the GAB, and deliver these via the existing website

6. Make additions and modifications to the existing website as requested by industry, addressing ideas for potential improvements identified by using the website over the past 6 years

7. Include more recent case studies on the website