Gold Rush Alaska

RTom said
I spent 3 years in college writing papers and doing studies regarding the salmon population and the effects of the dams along the Columbia and Snake River, this is where my knowledge comes from. While it may not be exactly the same for other areas, the general principles still apply.

The biggest thing that hurts the salmon in terms of the dams is the water getting cloudy and slow. Biologically, when the salmon are still young, they instinctively know to swim with the current and to reach the ocean. When they are older, and starting to migrate back to their spawning grounds, they instinctively know to swim against the current. What happens when the rivers are dammed up, is the current almost becomes non-existent ( think in terms of what the current would have been 500 years ago ) confusing the salmon.

Salmon also need clean, clear cold water to thrive in. Water that is dammed up and slowed down also warms up making it not very suitable for the salmon. The food niches that the salmon would ususally feed on ( in fast flowing water ) are not there in the slow lethargic water due to dams, decreasing drastically what they can eat.

But, before you get all gun ho about tearing down the dams, you need to realize that doing so will KILL more salmon that leaving them in place. You have 50+ years of silt built up behind these damns along the Columbia. When you tear down the dams, the silt will flow down the river choaking out all of the organisms living in the river. The most logical time to tear down the dams would be during late summer/early fall while the water flow is the lowest. This time also corresponds to some of the more endangered salmon runs ( at least for the Columbia Basin Drainage ). So, by tearing down the dams to save the salmon, you will actually be killing them and driving them ever closer to extinction.

RTom

RTom said
Sorry, I ment to tie in the part about dredging. The dredges will turn up all kinds of silt and heavy metals that will get into the water and affect not only how well the fish can breathe, but also affect the biologically.

There is an old ghost town in Idaho called Silver City. It used to be a huge mining town. Some of the mines up there ended up leaking toxic heavy metals into the watershed. If you catch some of the trout from the streams up there ( which you are warned not to eat due to the toxicity ) you can find traces of the heavy metals in them and see how it affected them ( stunted growth, immature reproductive organs etc. ) when you compare them to the same species of trout but from an unaffected water shed.

4spdragtop said
RTOM is pretty bang-on, Im going thru for Environmental right now and Salmon and Trout are extremely susceptible to temperature change. Also when there are dams, the water levels increase and decrease, so at the banks, they are sometimes submerged and other times not. This messes up the aquatic plant populations. Ok cant think of anything else, 3 weeks holidays and my brain is mush!!

dustoff440 said
It doesnt take much in toxic metals in parts per million to make fish inedible. Even fancy albacore tuna which apparently absorbs mercury more readily than regular tuna is not supposed to be consumed at all by pregnant women and sparingly by others.

Thanks guys for a well written intelligent response. I know when I was living in Chicago, the fish from Lake Michigan was not to be eaten by pregnant women. Mercury and PCBs were a huge problem. I don't know if it's gotten cleaned up somewhat. The bigger and older the fish, the more dangerous it was to eat. I used to go smelt fishing in the fall (just a big party on the piers, really) as those were relativley safe to eat. The next day we'd have a big smelt fish fry with a keg. Gotta love Chicago. Oops, off on a tangent, lol.

Great information and thanks for enlightening me.