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q-bio.PE · Populations and Evolutionq-bio.QM · Quantitative Methodsstat.AP · Applications

The mean 10–90% interval in May–August sockeye counts decreased by 1.4 days at four Columbia River dams from 1962–1993 to 1994–2025

Migration timing can change through an earlier season or a shorter season. We tested these changes in recorded adult sockeye salmon counts. We used daily counts at four Columbia River dams from 1962 to 2025. We compared 1962–1993 with 1994–2025. Each year had the same weight. The mean median date moved 5.84 days earlier (95% year-block interval: 3.76–7.88 days earlier). The mean 10–90% interval in May–August counts decreased from 21.48 to 20.04 days. Its change was −1.44 days (−2.76 to −0.09). Evidence for this mean decrease was sensitive to some analysis choices. Priest Rapids had the clearest decrease: −2.78 days (−4.44 to −1.16). The interval at Bonneville changed by −0.38 days (−1.59 to +0.94). A large late-season McNary count in 1978 made the wider-window decrease larger. We preserved this count and did not classify it as an error. These results describe recorded passage at dams. They do not measure individual travel time or identify causes. The package includes exact source files, source hashes, code, all results, and four figures.

sockeye salmon · migration timing · Columbia River · passage counts · phenology · block bootstrap · reproducibility

Admitted 1 citing publication

References

5
  1. usesTemperature and flow models fitted to 1950–1993 Bonneville Dam counts did not predict 1994–2025 run timing: sockeye came about 4 days earlier and spring Chinook 5–8 days later sci:sha256:bf1c076e279100386cc5490414e7713b7e1a79fefcefcf3bef20b82733f6fb02

    We reuse its retained DART daily source files and compare the reconstructed wider-window quantiles with its tables. We extend its median-date analysis to passage interval length.

  2. doi:10.2307/2265584

    This study reported earlier passage of sockeye and shad at Bonneville and tested environmental relations.

  3. doi:10.1111/j.1365-2419.2005.00354.x

    This study tested climatic relations in sockeye return dates across populations.

  4. doi:10.1086/662669

    This paper used time series methods to study earlier sockeye migration. We confirmed its title and authors. Its full text was not available in this investigation.

  5. doi:10.1371/journal.pone.0238886

    This tagged-fish study shows the relevance of timing and temperature for migration survival. It motivates our timing question; it does not validate our count intervals.

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