This project would focus on:
- Understanding the extent of the changed SBT migration, residence and behaviour (especially surfacing) patterns of juveniles within and around the Great Australian Bight (GAB) using PSATs
- Testing and refining the set-up and deployment strategy for use of next generation PSATs, which will assist in the design and implementation of this project and in future studies aiming to determine broader spatial scales of movement and habitat usage.
- Utilizing the latest climate reanalysis products to examine potential links between physical drivers in the ocean and atmosphere and changes in distribution of SBT.
The project will be staged with the first year deploying 15 existing PSATs provided in-kind by CSIRO to the project and a further 15 PSATs to be purchased using project funds. These PSATs are proposed to be deployed towards the end of the 2023 fishing season (likely March) via the addition of up to 4 days charter time to the CCSBT gene-tagging field work.
The purpose of these deployments is twofold:
1. To examine the suitability of current generation PSATs in terms of data resolution, data retrieval and tag retention rates required to answer the questions arising from the SBT ranching industry over recent years.
2. To obtain information on movement and residence areas of 2-3 year old SBT and detailed habitat data, especially with regard to surfacing rates.
Information gained from the first season will be used to guide and refine deployment of a PSATs in the second season. By deploying up to 30 tags in year 1 it is envisaged that there will be sufficient data for comparing current juvenile SBT distribution, behaviour and movement patterns with historical data.
The fact that the fish do not need to be recovered to retrieve the data means this project can deliver useful insight independent of fishery operations.
A core question that remains to be determined is how long these tags can remain attached to small tuna. The tag retention data that will be determined through this project will contribute to future tag technology improvements/development to ultimately help deliver answers to this industry’s specific questions.
The project would be focused on addressing the major sources of uncertainty for the operation of the SBT ranching industry – obtaining data on the distribution and habitat preference (depth/temperature regimes) of fish that formed the mainstay of successful ranching operations historically.
