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Data from: Geomorphic, hydroclimatic, and biotic factors influence juvenile emigration timing in a southern coho salmon population

Obedzinski, Mariska12; Grantham, Ted2; Horton, Gregg3; Pess, George4; Carlson, Stephanie2

Published May 08, 2026 on Dryad. https://doi.org/10.5061/dryad.x3ffbg823

Data files

May 08, 2026 version files 1.45 GB

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Abstract

Environmental variation gives rise to species’ life history diversity, which is essential to population resilience. Here, we characterize diversity in juvenile emigration timing in an endangered coho salmon population complex and examine physical and biotic factors contributing to phenological variation among streams and cohorts. Over 11 years, PIT-tagged coho salmon from common family groups were released from a conservation hatchery into four tributaries of the Russian River, California, USA, and we tracked their emigration timing using PIT detection systems. We estimated the probability that juveniles would emigrate early (< March 3) using a multistate emigration model and found that early emigration probability was higher in streams with less floodplain area and increased with streamflow, salmonid density, stream temperature, and individual size. Both life history strategies—i.e., early emigration and emigration during the typical spring smolt migration window—contributed to adult returns. The life history plasticity observed suggests that the remnant population responds to environmental heterogeneity and that efforts to diversify and reconnect a variety of habitats could stimulate multiple emigration strategies and increase population resilience.