Variation in the fatty acid composition of juvenile chinook and coho salmon from Fraser river estuary determined by multivariate analysis; role of environment and genetic origin

Abstract

Juvenile chinook and coho salmon were collected at five sites from the lower Fraser River and estuary for fatty acid analysis of brain, heart, gill-arch and muscle tissue during the winter and spring 1992. Using multivariate analysis, a novel statistical method for this type of data, we found that the fatty acid composition in various fish tissues differed. The brain fatty acid composition was least similar to the fatty acid profiles of the various food species, while the fatty acids extracted from gills showed a profile with more similarity to the food species. The rearing history (hatchery-reared vs. wild fish) influenced the fatty acid composition in the four tissues from both salmon species. The composition of fatty acids from the chinook brain tissue was influenced by developmental changes during the first year of life. In the chinook and coho smolts, species-specific differences were detected in brain and especially the heart tissue fatty acid profile. We suggest that the fatty acid composition from the heart tissue may be best suited to differentiate between juvenile chinook and coho, and it is believed that gill tissue is best to differentiate wild and hatchery fish.