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

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.