I know this thread started out with hatchery vs. wild fish spending, but the genetic interaction direction is certainly more interesting!

Many threads have been discussed on this BB over the last few years on this topic, and it seems the same arguments keep coming up about every few months...

Bob, you're certainly right about genetic interference on the Cowlitz...there hordes of hatchery fish in there year round, there is no semblance of temporal separation, and there is very poor habitat. Hatchery fish placed upstream from the dams are spawning and returning "wild" fish.

However, the Cowlitz is a poor example of a river to compare to any other river in Washington State due to the damming, diking, super-factory hatchery conditions, etc.

Pautzke, there has been a pretty good separation of genetics between hatchery and native fish runs...but not necessarily for any of the points made above, and certainly not without consequences, sometimes severe, for the native fish.

In any river where there are both hatchery and native fish, there will be overlap of spawning times ranging from not very big to almost complete overlap. Fish spawn in relation to a lot of different environmental factors, and a date on a map such as Feb. 28, or March 15, is not one of them.

Where there is overlap, hatchery and native fish will spawn together. They will produce smolts, and they will head downstream with the other naturally spawned smolts.

Here's the rub, however...they aren't likely to be back. Two hatchery fishing spawning in the wild are likely to result in the return of almost no adults. Statistically I believe the number is so low as to be pretty much "zero".

A hatchery fish spawning with a native fish will return more fish than two hatchery fish, but not many more.

Two native fish will return the highest amount, by far.

An important aspect of this to remember is that the "highest amount" returning by two native fish spawning is still not very many fish, in fact it's damn few. And they all are necessary to sustain the wild run.

That factor is of utmost importance when genetic drift is considered, because you can't stop looking when you find that there is a pretty good distinction among native and hatchery adults. The problem lies in the loss of native fish that results from the spawning of a native and hatchery fish together. It's actually worse for the native run for that to happen than if the native fish were caught and killed by an angler.

The problem is that the NxH cross creates several thousand smolts that compete with native smolts while in-river and on their way out. This competition for food and space is tough on all the fish in the river. And almost none of those fish return.

Whatever reproductive potential the native fish in the above hybridization had has been lost, but the competition created by additional smolts in the river has not been lessened.

It's a double whammy for the natives, but it doesn't cause much genetic drift between the natives and the hatchery fish. Maybe it's even a triple whammy, since the HxH crosses and HxN crosses are also competing directly with other NxN crosses for holding water and spawning gravel, too.

I believe that the studies done by Hulett, Phelps, Chilcote, and others have backed up those above assertions, especially those done on the Kalama River where upriver adults are genetically checked, as are all the smolts going down.

Of course, there are exceptions...but they are clearly exceptions to the rule. The aforementioned Cowlitz River is an obvious one, but obviously an exception due to significantly different conditions than anywhere else around here, except for perhaps being a small scale example of how the Columbia River hatchery system works.

Places like the S.Fk. Skykomish are exceptions, as well, but with reason. Miles of spawning habitat have been opened up due to the trucking of fish over the previously impassible falls...and hatchery fish are creating a "wild" run up there. However, there never were native anadromous fish there to begin with.

There are other exceptions, but rather than go through each and every one, I'd just assert that the above "rule" about genetic interaction problems is just that; a "general rule" for the problems caused by hatchery/native interaction in streams.

Fish on...

Todd.