Elemental fingerprints of otoliths from smolt of Atlantic salmon, Salmo salar Linnaeus, 1758, from three Maritime watersheds: Natural tag for stock discrimination
The utility of otolith elemental fingerprintsfor discriminating sub-regional stocks of Atlantic salmon was examined. Otoliths were removed from Atlantic salmon smolts collected from three individual river watersheds in the Canadian Maritimes during spring and analyzed for 27 elements using inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma emission spectrometry (ICP-ES). Calcium and minor and trace elements were precisely measured in whole otoliths at concentrations well above detection limits. Six elements (Ba, Pb, Li, Mn, Rb, and Tl) were significantlydifferent among watersheds. Linear discriminate function analysis based on otolith elemental concentrations of Li, Mn, Rb, and Tl correctly classifiedsmolts to their river of origin with an average accuracy of 73%. At a slightly greater spatial scale of large watersheds, correct mean classificationrate was 92% based on a fingerprintof four elements (Ba, Li, Mn, and Rb). Results indicate that elemental fingerprintsof otoliths can be used to discriminate among river management stocks which may be important in the future since dried or frozen stored otoliths retain their signature indefiniely and otoliths are often available from previous studies. Otolith elemental fingerprintswould be effective as a natural tag of a river system or biogeoclimatic zone of origin when applied to the study and management of Atlantic salmon in the North Atlantic Ocean.
