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Otolith analysis for determination of feral versus escapee Atlantic salmon



Incremental otolith growth occurs through differential deposition of calcium carbonate and protein over a 24-hour period. This growth of the otolith is a one-way process: new otolith material is added to the outside surface through time, but existing material cannot be removed. This results in the production of daily growth rings in the microstructure of the otolith, much as a tree produces annual growth rings. Daily growth rings visible through a microscope record daily age and growth patterns in surprising detail. The width and spacing of the daily growth increments are affected by the environmental factors facing the fish, including temperature and feeding. It is also known that the pattern of microstructure formation remains constant over the life span of the fish, therefore allowing the origin of an adult salmon to be determined based on the microstructure patterns formed throughout its life history.

This project will develop the technique of otolith analysis into a practical and scientifically defensible technique for distinguishing feral Atlantic salmon from aquaculture escapees for all age classes.

Program Name

Aquaculture Collaborative Research and Development Program (ACRDP)


2002 - 2003



Principal Investigator(s)

Andrew Thomson

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