I saw the strangest thing today.

[salvelinus]

A buddy and I were in the Poconos today and stopped at the Bushkill's Resica Falls to relax and enjoy the view. As we watched the falls, we observed many trout attempting to leap up the falls as if they were salmon. Water temps were around 70, why would the trout expend all that energy in soupy water for such a futile effort? Anyone ever see anything like this?

 

[salmonoid]

I think you named it. Water temps were around 70. The fish were looking for cooler water. It's either move up and find it, or roast and keel over in the water they were in.. I watched stocked brookies move up out of water that was just 58 degrees last weekend and that probably fluctuated between the range of 48-60 degrees; I think they somehow knew that with low water levels, temps could potentially spike anytime. Would love to know what the mechanism is that fish use to measure water temperature (i.e. what kicks in that alerts them that it is getting too warm or DO is getting too low). Anyone know how they sense temperature?

 

[Fishidiot]

salmonoid wrote:
I think you named it. Water temps were around 70. The fish were looking for cooler water. quote]

Agree.
To be sure, I can't recall seeing trout jumping falls at the onset of warm water - but it makes sense. Trout (and many other fish) can often be seen jumping, or attempting to jump, water falls or low head dams and this seems to be particularly common around transition periods - typically in spring or fall when fish are moving to or from spawning or wintering areas (or to better water temps).

 

[Maurice]

Hatchery trout will do this when under stress. Stress factors include; warm water/lower DO(related) or high density of suspended sediment (muddy water). Although I don't see 70 degrees to be a limiting factor especially if it is not sustained. However if these are State stocked hatchery trout that were raised in limestone spring sourced raceways it is likely they have never experienced these conditions and would flee when they encounter it for the first time.

Over time especially if they were raised in water temps that fluctuate they may become conditioned to tolerate short spikes in temperature.

Our nursery can and does reach 70 often in summer and peaks at 76 with no or minimal mortality if additional stressers are not introduced such as feed or muddy water.

We find that the trout we raise carryover better over summer than trout stocked by the state and I feel it is because they are conditioned at an early age to tolerate it.

 

[pcray1231]

Yeah, and I do know as soon as they are stocked, more fish seem to go downstream than up. But wherever they end up, as water temps warm, they tend to go upstream. I know many streams that are stocked in downstream sections, and come mid-summer, unstocked portions far upstream and full of wild fish are suddenly full of stockies from below.

If they want to go up, and there's a falls in the way, well, they'll try to jump it, nomatter how futile it is.

 

[JackM]

Trout cannot be expected to know how high a waterfall is. But they are smart enough to know that the cooler water and higher DO levels seem to be coming from the upstream direction. The closer they get to the falls, the better they feel.