The importance of early life history diversity in coho salmon

Abstract

Years of habitat loss, hatchery production and water regulation in the Puntledge River have potentially compromised diversity in coho salmon. Diversity was interpreted from age and early rearing history of mature coho that returned to spawn in 2009 (n=28). Life history groups were interpreted through a visual analysis of the micro-chemistry profiles in the otoliths. There were 2 age classes and 9 life history groups detected. Group differences in Sr:Ca, Ba:Ca and Mn:Ca were significant (p<0.0001) between groups with >2 members (n=6). Cluster analysis using Sr:Ca and Ba:Ca resulted in similar groups. Sr:Ca profiles indicate different rearing habitats, coho that reared in both freshwater and the estuary, and a Jack that reared entirely in the estuary. Results support the need for further studies on the extent of diversity in Puntledge coho, and management actions that identify, restore and protect important rearing habitats.