Salmon Stock Identification Using a Microanalytic Technique to Measure Elements Present in the Freshwater Growth Region of Scales

Abstract

Scanning electron microscopy combined with energy dispersive X-ray analysis was used to measure the chemical composition of the freshwater growth region of salmonid scales. Adult sockeye salmon (Oncorhynchus nerka) scales from three lakes on the west coast of Vancouver Island were analyzed and the data were subjected to multivariate statistical analysis. The fish from the three lakes were found to be chemically distinct, enabling 63% of the fish to be correctly classified to their lake of origin. This stock identification technique can differentiate populations, allows reduced sample size, and requires no handling of juvenile fish.Key words: stock identification, salmon. X-ray analysis, scanning electron microscopy, multivariate analysis