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Abstract

Tagging fish without gathering physiological informationmay be awasted opportunity.We tested bioelectrical
impedance analysis (BIA) for measurement of relative condition of southern bluefin tuna (Thunnus
maccoyii) during conventional tagging at sea. We refined the equipment and method by measurement
of 360 fish during conventional and acoustic tagging. Our results demonstrate that BIA is an accurate
measure of condition for southern bluefin tuna in the same way it has been shown to be for metabolic
condition and composition in other vertebrates including humans. Further, there is sufficient variation
in BIA measures of the natural population to give meaningful measures of both metabolic condition and
composition between groups at different times and developmental stages. Condition of tuna in this study
may be related to the ocean environment just prior to measurement. BIA meets the necessary objectives
for measuring fish condition during tagging as it is shown to be harmless, reliable, quick, and effective
and does not disrupt conventional tagging operations. In the light of these results this type of condition
measurement should be taken wherever possible in future tagging operations for this and other similar
species, which will generate new insight into the ecological challenges faced by pelagic fishes. The ability
to relate recent ocean environments and subsequent patterns in fish survival may lead to changes in the
way tagging data is interpreted.

Item Type:	Article
Authors/Creators:	Willis, J and Hobday, AJ
Keywords:	Physiological condition Conventional tagging
Journal or Publication Title:	Fisheries Research
ISSN:	0165-7836
DOI / ID Number:	https://doi.org/10.1016/j.fishres.2008.02.010
Additional Information:	The definitive version is available at http://www.sciencedirect.com
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