This project is needed to support improved operational planning in the SBT purse-seine fishery in response to recently observed changes in fish distribution. A historical baseline of fish and ‘optimal’ habitat distribution is first needed to assess future changes. An understanding of likely fish location is important in planning fishing operations and will also be of benefit to the aerial survey (AS) design and data interpretation. The AS juvenile abundance index is used in the adopted management procedure for SBT to set global quotas (within the CCSBT).

In the 2012 fishing season, SBT movement through the Great Australian Bight (GAB) seemed very rapid, and with SBT distribution further to the east, resulting in less than 15% of purse-seine catches being taken from fishing grounds commonly used in the previous 20 years. Rapid movements of surface schools and the presence of fish in unusual locations make fishing operations costly and unpredictable; the pontoon towing speed precludes rapid vessel response, so vessels need to be positioned prior to SBT arrival. Improved understanding of fish distribution/movement in the GAB will allow evaluation of the adequacy of the current AS design, and inform improvements to the design/analysis if required.

Forecasts of environmental conditions (lead times < 4 months) will allow operators to use their existing knowledge of fish behaviour to better plan fishing operations in any year, not just unusual years. Forecasts of fish habitat (if successful) will further aid this planning and improve strategic fishing skills, leading to increased efficiency/profitability. Seasonal forecasts are also a stepping stone to understanding longer term climate change, but at a business-relevant time-scale.

The project aims to use existing data and modelling techniques from previous projects funded under broader public good research programs; however, previous projects have not developed the tactical forecast products proposed here.