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Trophic Dynamic
Tuesday, 14 April 2009 11:09

Understanding the structure and dynamics of pelagic ecosystems is critical to develop ecosystem approach to fisheries management. It allows assessing the impacts of fishing activities and environmental factors not only on target stocks but also on all other species including by-catch and protected species belonging to this ecosystem. The structure of the ecosystem is based on prey-predator relationships that are the most important interactions between species. Studying the trophic dynamic leads to the development of ecosystem models which provide the basis to test ecosystem-based management options and provide management and monitoring advices to the WCPFC and Pacific SIDS.

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Age and Growth
Tuesday, 14 April 2009 11:21

In stock assessment the growth rate is often influential and accuracy and precision in estimates are important to ensure the assessment is as accurate as feasible.  For many years, OFP has undertaken research to establish the methods to age tropical tunas and estimate their growth rates and how the environment influences growth.  Most of our work has been applied to ageing tuna using cross sections of otoliths including bigeye, yellowfin and south pacific albacore using both daily increment and annual increment techniques.

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New study on albacore reveals that males grow larger than females
Thursday, 21 June 2012 10:43

plos_oneIn 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.

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Reproduction
Tuesday, 14 April 2009 11:22

Stock assessments require estimates of reproductive parameters that are used to describe the population dynamics of the species. However, some of the estimates used are uncertain, either because of missing or scarce biological data, or because data had not yet been analyzed. On an ongoing basis OFP undertakes the data collection and analyses to reduce this uncertainty.  Sustainable fisheries need continued reproductive output, and so stock assessments use spawning biomass in stock status indicators and reference points.

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Migration Patterns
Friday, 06 February 2009 10:48

Scientists place conventional plastic tags on tuna which provide information on growth, fishing mortality, natural mortality and movements when recaptured. These important population parameters are used to estimate the status of tuna stock and the impacts of fishing. Another form of tagging, using electronic tags, provide detailed information on fish movements in relation to their environment.

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