C
ClearCreek
There is almost no O2 when the water temps comes up into the upper 50's and 60's,
AA - not sure where you heard that, but it is NOT true!! Water 50-60 degrees F has plenty of oxygen for salmonids!
ClearCreek
I don't think it's quite that simple. 60 degree water has almost half of the dissolved oxygen content that 38 degree water does in PPM. Now if you combine other factors including low water, warm days and increased underwater plant growth the oxygen content can decrease even further. Given the nature of our rivers here in the NW and the amount of heating it takes for the water to reach 60 degrees there normally is a substantial amount of underwater growth. I would venture to say that when our rivers reach this temperature the oxygen content is likely to be insufficient for the average salmon or steelhead as they use 4-5 times as much oxygen at 60 degrees as they do at 38.
Balderman:
I am not sure where you get your info either, but your statement is not true!! Water at 38F has very close to 13.3ppm oxygen, while water at 60F has very close to 10 ppm oxygen. Not even close to half as you mentioned. 10 ppm oxygen is plenty for salmonids!!
As far as the underwater plant growth, during the day those green plants ADD oxygen to the water!! And, any surface turbulence in a river will agitate the water which will also add oxygen to the water.
Just wondering - how many dissolved oxygen samples have you taken in streams or lakes??
ClearCreek
First of all, I never said my figures were 100% correct nor did I say I sampled water for a living. I think your figures for the 60 degree water are too high, more like 7-9ppm but I am not going to say you are wrong cause I don't know for sure, I was just generalizing. In regards to the plant growth I should have clarified that when the plants die they release large amounts of nitrogen into the water thus reducing the oxygen content. These blooms occur and die off several times during the summer. Secondly, yes water turbulence will add oxygen, have you ever seen the clackamas river in the summer? It loses a LOT of it's turbulence, in fact many stretches of the river become "frog water" thus reducing the oxygen content. I think all of this combined with the fact that salmon need 4-5 times the oxygen at 60 degrees than at 38 degrees means that the water temperature is definitely going to change their holding areas.
With all that said I don't know why you are being so rude with your posts. No one on here said their data was scientific, just making observations about why fish change their behavior......relax man.
Blderman:
Take a look at the graph that beaverfan posted. 38F is about 3.3C and 60F is a about 15.5C. The oxygen concentrations are just as I indicated.
I am not being rude, I just don't like this kind of misinformation being posted on these fishing websites. Especially when there is so much info available on the net if you take a few minutes and search for it. The graph that beaverfan posted is a great example.
Your statement that salmon need 4-5 times the oxygen when the water temperature is 60 vs. 38 does not seem logical. Could you post the data you have to show that is the case? I would like to see it. Thanks (I said thanks, that is not being rude).
ClearCreek
OK,
When I look at that chart I see 13+- PPM at 38 degrees and 8PPM at 60 degrees......So not quite half.....sorry I was 2ppm off!:shock: Ironically enough if you read the link that Beaverfan attached the chart with it states that at 77 degrees trout need 5-6 times as much oxygen as they would at 41 so my theory of 4-5 times as much at 60 degrees probably isn't too far off. Again, though I didn't see where anyone was claiming to be scientific here.....
Did you hear the one about Jim and his fishing buddies? Seems the three of them had been fishing every Saturday for nearly forty years. They were at their favorite hole when a funeral procession slowly went by. Jim immediately put down his rod,stood up in the boat and put his hat over his heart. The procession lasted at least 10 minutes,Jim never flinched. When it finally passed,his buddies were in awe of him. "That was a mighty respectful thing you did there,Jim" one of them said. "Well,I was married to the woman for over forty years,I felt I owed her that much"...
Blderman:
I am not sure how you see 8ppm at 60 degrees F. Please take a look at the graph (of the right side, down a little) at this link:
EPA > OWOW > Monitoring and Assessing Water Quality > Volunteer Stream Monitoring: A Methods Manual > Chapter 5 > 5.2 Dissolved Oxygen and Biochemical Oxygen Demand
60 degrees F is 15.5 degrees C and the oxygen at that level is right at 10 ppm.
You said you were just 2 ppm off, well 2 ppm dissolved oxygen can make a very big difference in the health of salmonids. The difference between doing fine and a fair amount of stress!!
Claiming to be scientific or not, this is science. It is basic limnology!! While fishing may or may not be scientific, understanding some basic science as it relates to fish will make you a better fisherman.
ClearCreek
One more thought...although you all have hit the mark extremely well. Steelhead, unlike salmon, eat the entire time they are in freshwater. They are hoping to make a return trip to the salt so their digestive systems do not get absorbed into their systems to make room for reproduction like a salmon who is in freshwater only to spawn and die. Therefore, steelhead will often find holding water that has the perfect conditions for insects and smaller baitfish. This is why both heads and tails of pools are so excellent. The heads have a constant flow of life tumbling out of the upstream riffle, and the tailouts have loads of perfect river rock for caddis, stones, and the little fish that eat them. The heads of pools have more cover and often steelhead can be accessed more easily without the fisherman spooking them. The tailouts have more bugs, bait, and hydrolics, but the fish are more wary in the shallower water. So sneak up on tailouts and fish them carefully. Tight lines....
Excellent addition to this thread. If you can't move into the 10% club with all this adavice you should take up golf.