In the first stock-wide study of tuna growth, scientists at SPC have discovered that male South Pacific albacore (Thunnus alalunga) grow larger than females, and that albacore in the central Pacific grow larger than those in the west.
Published in the journal PLoS ONE, the research article is authored by scientists from the Secretariat of the Pacific Community and Australia’s CSIRO Marine and Atmospheric Research.
The study was made possible by the dedication and significant efforts from the many fisheries observers, port samplers, fishers and scientists who participated in the collection of over 3000 otoliths (ear bones) and other biological samples from albacore across the South Pacific Ocean, from the east coast of Australia to Pitcairn Islands.
Over the past 3 years, scientists have analysed nearly 2000 of these otoliths to estimate the age of each fish and to determine growth rates. Results have shown that, on average, male albacore grow 8 cm (~6kg) larger than females, and that albacore in the central South Pacific can grow 6 cm (~5kg) larger than those in the west.
These findings are significant for regional stock assessments for South Pacific albacore because previous assessments have assumed that growth rates were the same for males and females throughout the South Pacific Ocean.
The results from this study provide the opportunity to refine and improve the structure of the stock assessment model. Such improvements will provide more reliable estimates of biomass, fishing mortality and potential yields, and ultimately provide the foundation for more robust management decisions for South Pacific albacore.
For more details, the entire research article can be downloaded from the PLoS ONE website.