Hatchery steelhead didn’t affect wild winters on Clackamas River, scientist say

A research study published this past weekend by the American Fisheries Society will almost certainly heat up the hatchery vs. wild debate about steelhead.

A scientific review of 59 years of summer and winter steelhead runs on the upper Clackamas River shows “… there was little evidence to suggest a negative effect of hatchery summer steelhead abundance on winter steelhead productivity…. Overall, environmental factors appear to have been more influential than the abundance of hatchery fish … in the upper Clackamas Basin,” the Oregonian/OregonLive reported Wednesday.

And, toward the end of the paper: “In this case, the segregated summer steelhead hatchery program coexisted with the natural-origin winter steelhead population without negatively impacting adult winter steelhead recruitment.”

The summer steelhead program ended in 1999 out of concern the hatchery fish might be weakening the wild run.

However, the study concludes there was no corresponding increase in winter steelhead productivity after it ended. Wild numbers remained largely static until recent passage improvements in both the River Mill and North Fork dams over the past couple of years.

The research and conclusions were led by Ian I. Courter of Mt. Hood Environmental in Boring and included scientists from the firm, PGE, the U.S. Geological Survey and the Columbia River Intertribal Fish Commission.

The study is available online at the American Fisheries Society Online Library. Here is a free link for those without an account.

While studded with formulas and scientific terminology, the study suggests the summer steelhead program resulted in limited spawning by adult summer steelhead above North Fork Dam. More than half were caught by anglers each season in a highly popular program.

Summer steelhead also appeared to prefer the lower mainstem and larger waters while winter steelhead move into smaller upriver tributaries to spawn.

Further, the run timing and spawning cycles of summers and winters were in different months.

Ocean conditions, coupled with outmigration difficulties during spill at PGE’s dams were more likely to limit wild winter steelhead, the study suggests.

Winter steelhead numbers have recently risen, but while they appear to be responding to the improvements, it will take a few more years of research to prove it’s a result of the new collection and passage facilities.