SCIENCE@home

Causes and consequences of juvenile migratory diversity in a wild population of yearling Chinook Salmon

Samuel Owens,Timothy Copeland,Bryce N. Oldemeyer,Brian P. Kennedy

Published 2025 in Transactions of the American Fisheries Society

ABSTRACT

Yearling Chinook Salmon Oncorhynchus tshawytscha commonly exhibit variability in timing of departure from natal habitats. An early-migrating group (downstream-rearing type) moves to downstream freshwater habitat as age-0 parr, where they remain until seaward migration. In contrast, a later-migrating group (natal-reach-rearing type) remains within the natal reach until smoltification. We assessed factors that could influence the expression of these two juvenile migratory strategies in a wild population of yearling Chinook Salmon. Additionally, we examined whether variability in behavior influences population dynamics across multiple life stages. Variables that could explain migratory propensity, including density, size, temperature, and discharge, were examined concurrently with trends in juvenile migration. Additionally, PIT tag events at six sites throughout our study system were used to quantify and compare discrepancies in juvenile demographics and adult survival. Over the 15-year data set, none of the evaluated variables had a significant impact on the expression of migratory tactics. However, we found significant differences in juvenile growth rates, smolt size, time of ocean entry, and survival to adulthood between the two groups. On average, individuals that expressed downstream-rearing behavior grew more over winter, produced larger smolts, entered the ocean earlier, and survived to adulthood at higher rates. Our findings suggest that variability in juvenile migratory behavior influences subsequent performance. Therefore, juvenile migratory behavior continues to shape population dynamics for the entirety of a cohort’s life cycle.   

PUBLICATION RECORD

CITATION MAP

EXTRACTION MAP

CLAIMS

  • No claims are published for this paper.

CONCEPTS

  • No concepts are published for this paper.

REFERENCES

Showing 1-66 of 66 references · Page 1 of 1

CITED BY

  • No citing papers are available for this paper.

Showing 0-0 of 0 citing papers · Page 1 of 1