Coastal Oregon Chinook: Spring and Fall Run Populations


Following my recent post on Oregon coastal steelhead populations, why not review ODFW’s classifications of fall and spring chinook Species Management Units (SMUs) and populations?

Juicy stuff, for all you fish science and salmon management geeks out there.

Oregon coastal Chinook are categorized by ODFW into two Species Management Units,the Coastal and Rogue SMU>

These SMUs are further divided into roughly 28 populations of fall run fish, and only nine historical  populations of spring run fish (at least two are currently thought to be extinct).

Spring chinook salmon are far less widely distributed than fall run fish, but are not nearly as rare as native runs of summer steelhead in Oregon coastal rivers.

This information was compiled from the ODFW Native Fish Status Report.

http://www.dfw.state.or.us/fish/ONFSR/report.asp#fall_chinook

Anyone wonder why spring chinook might be more common than summer steelhead?

JN

4 thoughts on “Coastal Oregon Chinook: Spring and Fall Run Populations

  1. I also wonder whether a spring chinook hatchery program in the Siuslaw and Lake Creek might be a good idea, both for anglers and for the basin’s productivity. Local bios indicate that the river is probably inhospitable to adults in summer, but there may be some cool water refugia hiding somewhere in the basin. I would certainly prefer that to a catchable trout program in the estuary, and I think it would generate a lot more excitement!

  2. I certainly do. All systems with a historical summer steelhead run have a historical spring chinook run. But why? I might have a simple idea, but I’m sure there is a better more eloquent story. Maybe the systems with spring chinook but without summer steelhead get too warm for young steelies to survive the summer, while the ‘nookies take the spring express to the estuary before SPF 90 is needed. Jay I don’t remember the life histories of coastal spring chinook (i.e. if they spend an entire year in stream after hatching before making the trip to saltwater). Habitat and food for the little ones must be present for one to survive, but why not both? Spawning times? Large falls? I’m open to an education. CD

    1. Cameron: you are on the right track to start with comparing the life histories of the two species. Before I ramble a little, let’s note that I do not really know what the “right” answer to this question is. Now let’s see, both Sts and Chs adults have to endure the heat of the summer flows, at least that is true for the Sts and Chs that enter early in the season (pre July). I am not aware that Chs adults have a greater tolerance to warm water, so I’d toss that one out. I think you are correct that many of the Juvenile Chs are capable of migrating to the estuary to rear for the rest of the summer in ocean-cooled waters, but that the vast majority of juvenile Sts stay up in the river proper or tributaries and are not well suited to estuary residence. So this could be a factor.

      But, Hummmmm, I am not aware of a temperature tolerance difference between juvenile Sts and Stw, so if virtually every coastal river has winter steelhead populations, how come so few have summer steelhead populations? Sympatry of species and run timings depends in a large part on being able to maintain reproductive isolation. I wonder if the Siletz (a natural falls might have served as a separator) and the two largest rivers (Umpqua and Rogue) provide more opportunity for Sts and Stw to segregate their spawning locations, since there is, I think, a fair amount of overlap in spawning time of winter and summer steelhead. Spring and fall Chinook, on the other hand seem at least today, to have relatively distinct spawning times, with the springers being pretty much done before the fall fish begin spawning.

      Enough droning on without a positive answer. I think the matter still merits further discussion, and some thinking about whether the run diversity means to our conservation and fish management programs.

      Thanks for being a fish sleuth! JN

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