ASFB Home > 2003 > Biological Invasions: Consequences for Parasites, Pathogens, Emerging Diseases, and Fisheries in the Marine Environment.

Testing assumptions of migratory reconstructions using otolith chemistry

Elsdon, Travis S., and Gillanders, Bronwyn M.

Southern Seas Ecology Laboratories, School of Earth and Environmental Sciences, University of Adelaide, South Australia 5005, Australia.
Email: travis.elsdon@adelaide.edu.au

Understanding movements of individual fish is central to the management of stocks and conservation of important habitats. While methods of determining fish movements are often traditionally based (e.g., capture-recapture), a recent advance is the use of chemical elements within fish otoliths to infer movements, where differences in elemental concentration are related to environmental variables such as water temperature. Testing assumptions that elemental concentration varies with environmental variables is rare and the extent to which migratory patterns of fish can be inferred from otolith chemistry is consequently unknown. Our experiments have shown that the otolith chemistry of juvenile bream (Acanthopagrus butcheri) is influenced by environmental variables. Temperature and salinity interact to influence otolith chemistry so that reconstructing fish movements using either temperature or salinity alone would give inaccurate reconstructions of movement. Furthermore, ambient elemental concentration also influences otolith chemistry. The results highlight the need for research investigating the effect of environmental variables on otolith chemistry if we are to use otolith chemistry to track the movements of fish.

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