Life history diversity and marine growth of Puget Sound Chinook using otolith microchemistry and scale morphometrics

This study seeks to better understand factors limiting recovery of Puget Sound Chinook salmon by measuring age, marine growth, and juvenile life history parameters within Puget Sound in comparison to coastal Washington juveniles and successful Puget Sound and coastal Washington returning adults. This research activity tests the hypotheses that juvenile life history diversity varies among regions and that marine survival is influenced by early marine growth and life history diversity.

Researchers are using otolith chemistry to examine life history diversity and marine growth of Chinook populations in multiple regions of Puget Sound and coastal Washington. By investigating juvenile parameters such as size and timing of ocean entry and determining which of those juvenile outmigrants survive to return as adults, researchers evaluate to what extent life history diversity and growth vary among populations and regions, and how that variation influences marine survival. Marine growth data produced by this study also benefits forecasting models for salmon management.

Preliminary results of this research activity suggest regional differences in success of life history strategies. Chinook populations from North Puget Sound watersheds have higher proportions of successful fry outmigrants than South and Central Puget Sound Chinook populations. Additionally, size at ocean entry differs between Puget Sound and coastal populations, and first-year growth appeared to be positively related to overall marine survival.