March 17, 2022
Olympic Peninsula (OP) steelhead (oncorhynchus mykiss) runs used to be greater in population and earlier in season, according to a study published in the North American Journal of Fisheries Management in November of 2021.
“Our analysis of non-ESA-listed populations, considered until very recently to be healthy, suggests that the lack of historical baselines can underestimate the loss of population diversity and abundance, thereby masking the need for conservation action,” the article entitled Historical Records Reveal Changes to the Migration Timing and Abundance of Winter Steelhead in Olympic Peninsula Rivers, Washington State, USA, said. “Our results for OP winter steelhead demonstrate how even a relatively modest extension of the period of record (e.g., 30 years) can increase the power to identify patterns of change that may not yet be apparent from contemporary monitoring programs.”
In effect, the study, which was funded by Trout Unlimited, the Wild Salmon Center, the National Oceanic and Atmospheric Administration, and the Wild Steelhead Coalition, analyzed data from the past that had not previously been parsed out for use in steelhead research, thereby adding about 30 years of historical context to the run size and timing data. This will ideally help researchers avoid what is called “shifting baseline syndrome,” which basically means that over time, accepted norms for a given condition tend to shift to more recent data/observations as the norm, and historical norms are slowly lost.
For example, researchers were able to use information from steelhead canning operations from 1923 on the Queets River to determine how many fish were likely in that year’s run. It also analyzed Indigenous, commercial, and recreational harvest data from the 1940s through the 1960s to determine size and timing of the OP’s winter steelhead run.
Results indicated that runs began earlier in the season and lasted for longer periods of time on Quillayute, Hoh, and Queets rivers, in the past. “Contemporary wild winter steelhead migrations peak 1-2 months later than historical migrations, and migration timing breadth has contracted by (about 37 percent),” according to the study’s abstract.
It also showed that run sizes had come down from tens of thousands of fish in the historical period to mere thousands from 1980-2017. Specifically, the Quillayute run declined by about 38 percent, the Hoh by about 69 percent, the Queets by about 50 percent, and the Quinault River’s run had been reduced by about 63 percent in those decades.
“We estimate that contemporary mean wild winter steelhead abundance has declined by 55% across populations compared to circa 1948-1960 historical means, with 1920s records suggesting declines of up to 77% in the Queets River,” said the study’s abstract.
Read more about this study here.