All,

The parasite is an intestinal fluke called Nanophyetus salmoncola. This is the same fluke that causes “salmon poisoning” in dogs that eat raw salmon flesh. It is common to many rivers, but for some reason is especially abundant, or hot, in south Puget Sound tributaries like McAllister Creek and the Deschutes River. Chinook salmon are the most susceptable salmonid species to this fluke. The intermediate host is the freshwater snail Oxytrema, where rediae develop. Cercariae are released from the snail and they penetrate members of trout, salmon, and char genera of fish.

The native resident cutthroat trout of the Deschutes River are also susceptable to the fluke, but having co-existed with it for centuries or more, they are more resistant than other species of fish that have been stocked there. For a salmon hatchery to be successful on the Deschutes, a fluke-free groundwater supply will be necessary for the functions of egg incubation and juvenile rearing. I do not think the Deschutes can sustain a natural chinook run of any significance, nor possibly of any other species, since the resident cutts would have a competitive edge due to their greater resistance to Nanophyetus. The river presumably could sustain hatchery runs of salmon and steelhead, if large enough numbers of hatchery smolts are stocked. It just doesn’t seem realistic to expect the hatchery fish that escape to spawn naturally in this stream to develop or sustain natural wild runs.

The former return of decent numbers of hatchery steelhead is most attributable to stocking more hatchery smolts during a period (1980s) of higher ocean survival. Ocean survival of Puget Sound steelhead is about one third of what it was during the 80s, hence, with fewer smolts planted, piddly returns.

Chum man,

Do you really want a chinook fishery on the Deschutes? I agree that it would be an ugly snagfest, as there is next to no water in September and October. I think the program better serves the various saltwater fisheries, like the August fishing at several popular south sound spots.

Downriggin,

I also thought McAllister was closed due to budget reasons, so I checked. It turns out that McAllister was never very productive anyway. Nanophyetus was only part of the problem. One of the risks explained to me was that returning adult chinook were loading up with the parasite. Then they could be eaten by raccoons or other animals, carry the cysts for years, and eventually deposit them in another watershed, like the Nisqually or Skookumchuck and infect them. The hatchery site was intertidal, so vibrio disease was also a problem. The upshot is that the production from that facility performed poorly in terms of contributions to fisheries. Plus, the few returning adults were of low value to the treaty fisheries, compared to those in the Nisqually. McAllister was originally built without the appropriate and necessary permits and was never a good fit for south sound salmon production. If WDFW is able to construct the proposed hatchery on the lower Deschutes, which also has an abundance of disease-free groundwater, the future chinook program appears likely to contribute more chinook to actual harvest than the past Deschutes and McAllister stations combined.

Buck,

Everyone would like a self-sustaining silver run, but that might not be in the cards. Other south sound streams that are hot with Nanophyetus have few or no silvers, so a strong coho run might be a long shot. Also, some years are much worse than others for Nanophyetus. I don’t know what stocks of steelhead have been stocked in the past; presently I think they stock from Puyallup. WDFW is reducing the amount of inter-basin transfers compared to the past, partly for disease, genetic, and other management reasons. I haven’t heard that the new hatchery will raise steelhead, although it probably could.

Sincerely,

Salmo g.