On Track to Rebuild SBT Stocks

Calculating catch quotas for Southern Bluefin Tuna (SBT), Thunnus maccoyii, has historically been a highly political and internationally sensitive issue. At the heart of the problem has been the need to balance the ongoing harvesting of SBT by nine international fishing fleets with efforts to conserve and rebuild stocks of this overfished species.

CSIRO scientists have been leading SBT research for decades. In the 1980s they calculated the extent of the species’ decline from the heavy fishing since 1955 to have resulted in a population that was about just five per cent of the size of the unfished population in 1931.

Since then they have continually developed new approaches to more accurately assess fish stocks and underpin management procedures designed to allow populations to rebuild.

Richard Hillary, from CSIRO Marine and Atmospheric Research, says in the past, catch quotas would be argued and worked through each year. But a new formula was adopted in 2011 to set quotas within a range that will help rebuild stocks to the international target of 20 per cent of unfished level. This formula is a simulation-tested decision rule that is based on inputs acceptable to countries participating in SBT conservation efforts through membership of the Commission for the Conservation of Southern Bluefin Tuna (CCSBT). The simulation is used to calculate a total allowable catch (TAC) for the fishery for threeyear periods. Richard Hillary says the new approach is more orderly and scientifically based and has helped to remove the wrangling and uncertainty from the process.

Improvements in data about SBT populations, combined with the new management procedure, have allowed quotas to be increased in recent years after drastic cuts were made in 1988, and smaller cuts in 2006 and 2009, to help stocks rebuild.

Southern Bluefin Tuna Tagging

Industry Partnership

The Australian SBT industry is significantly smaller today than it was at its peak in 1982, and it has supported efforts to improve the science behind the management of the fishery for more than two decades. The Australian SBT industry has invested strategically with the FRDC in key pieces of research that have greatly improved knowledge of the species and stock status.

This includes CSIRO’s work to develop a new quota calculation formula as well as ‘Close-kin’ matching and tagging projects which directly estimate the abundance and movement of SBT populations respectively.

CEO of the Australian Southern Bluefin Tuna Industry Association Brian Jeffriess says the long-term partnership between the FRDC, researchers and industry has produced valuable research. “The industry knew that the new projects, and the move to setting the quota by scientific models, would not be welcomed by everyone. However, it was the only way to ensure the sustainability of SBT and the communities dependent on it,” he says.

 

Article Reference: FISH News, Fisheries Research and Development Corporation, Volume 20 Number 4, December 2013, pp 16-20.

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