Why Rainbows?

[Maurice]

No TB I was not there...but a rep from our TU was and that's what he said occurred...And he indicated it wasn't even close. Our reps vote was for more trout, browns.

Hey, he was disgusted too...

 

[Chaz]

LetortAngler wrote:
I remembering reading a while back, that when the PFBC started stocking rainbows, they would not stay in place and would always migrate to larger river systems.
Maybe that explains why bows have not established themselves in more streams across the state with the majority of stockings being rainbows?

Years ago it was accepted as truth that rainbows ran long distances, back in the early days of stocking that probably was true, according to Dr. Robert Behnke, the early bows that came from California were in fact mixed with their sea-running cousins steelhead at the early hatcheries, therefore 'rainbows' were susceptible to migration. They are actually the same species.

The more recent info we have available is from 2 sources. PFBC, and T.U. PFBC studied stocked fish residency, and found the bows were most likely to stay where they were stocked. T.U.'s study of the Delaware R. wild bows showed they migrated long distances for food, cold water, and spawning.

 

[LetortAngler]

Thanks Chaz, that sounds about right.

 

[sarce]

jifigz, I've caught stocked brookies unexpectedly in water that was probably mid-70's, and just about all of the native brookie streams I fish in the SE part of the state get close to or a bit over 70 degrees for a few weeks every summer.

 

[Chaz]

jifigz wrote:
What does it mean on the table when the Brook Trout have two temperatures on the "Upper Limit Adult" section? I am pretty sure that Brook Trout cannot survive anywhere near the 78 degree mark...I could be wrong, though. And if Brook Trout can't tolerate 78 degree water, which I don't believe they can, then their upper limits vary more than their omptimum water temperatures.

It's well established that brookies upper temperature limit is around 78°, however they can survive higher temps for short periods.the lower number must be the temperature at which brook trout start to lose weight, or rather fail to gain weight. In other words they are threatened by mortality if caught at the lower limit or above.
Again they are stocked in waters most suitable for there survival.
Rainbows are least likely to establish a wild population from stocking so they are stocked in a lot of waters.

 

[troutbert]

I saw both wild brookies and browns in a stream that was 79F.

 

[Chaz]

Maurice wrote:
No TB I was not there...but a rep from our TU was and that's what he said occurred...And he indicated it wasn't even close. Our reps vote was for more trout, browns.

Hey, he was disgusted too...

Maurice there were several different discussion groups. the group I was in said fewer but larger fish, and it was unanimous. Like TB said I think it was used to divert attention from not stocking wild streams and other more beneficial things that could improve wild trout populations. I believe that was the consensus of the Trout Summit.
I told them flat out I didn't care what they did on stocked streams, but did suggest that they put the fish where the most anglers fish, that they were wasting their money putting trout in wild trout streams and in streams with little or no use. They should improve their efforts on wild trout stream especially habitat.

 

[PennKev]

jifigz wrote:
What does it mean on the table when the Brook Trout have two temperatures on the "Upper Limit Adult" section? I am pretty sure that Brook Trout cannot survive anywhere near the 78 degree mark...I could be wrong, though. And if Brook Trout can't tolerate 78 degree water, which I don't believe they can, then their upper limits vary more than their omptimum water temperatures.

I think those upper limits are the point at which the temperatures have an immediate and adverse affect on the fish. Brown trout are not going to last that long at 80 degrees either.

In the various "too hot to fish?" threads I've mentioned that elevated temps are not like flipping a switch where all the fish suddenly die. It takes days or weeks too kill the fish depending on just how high the temps are. With that said, I have a feeling that 78 for brookies and 80 for browns are the temps at which mortality becomes very rapid if those temps are sustained for any length of time.

I'm not speaking from scientific knowledge, but rather from my experiences with trout stocked in streams that get quite warm and how that experience matches the data.

 

[jifigz]

Good info all. I am surprised by the number of people that are offering support in the case of Brookies being able to survive water that warm. I did not believe that was the case, but it appears that I was wrong. I'm going to have to mintor the temps on my native brook trout haunts during the dog days of summer just to see what kind of temps they hit.

 

[sandfly]

Why rainbows ?
because they take power bait better than the others !

seems the bows did better than the browns on pine last year, all I caught all summer was bows. the browns headed to cooler water while the bows stayed in the riffles all summer.

 

[jifigz]

Chaz, so let me get this right. You are implying that above 68° Brook Trout mortality rate climbs after being caught? this would then imply that the number for Browns of 73 would mean the same thing for that species....I'm not sure I'm believing that that is what that lower number means....but I don't know. I'm going to look into it.

 

[JackM]

My understanding of "upper lethal limit" is that it must reach that level and stay that high for at least 24-48 hours. So the trout can survive temps that surpass the lethal limit as long as it isn't sustained and they get some recovery time in between.

 

[sarce]

That's my interpretation as well Jack.

Some very good wild brown streams see temp spikes to at or above 80 degrees when summer afternoon storms send a surge of water running off hot pavement. Valley Creek and Slab Cabin Run (Centre Co) are two examples. I've noticed a few dead trout after such events but both are still class A streams. The temp spike is very brief.

 

[rj32s]

I always assumed it was for economical reasons, never having looked into the issue.

With that said, catching a rainbow is a wonderful thing, but not as wonderful as catching a brown

 

[Eccles]

jifigz

Critical thermal limits are really assessed as the interaction between temperature and time. So, for example, you might hold a fish in a water bath at a particular temperature and note down the time it loses righting ability. Then rack up the temperature a couple of degrees and repeat. From the data you produce a curve of loss of righting ability over time exposed to increasing temperature. The two temperatures quoted for the brook trout for example may represent something like the temperature at which adverse effects are first noticed (albeit after considerable exposure time) and the second temperature the one at which such adverse effects occur in only a few hours/minutes. It is the range of temperature over which some stressful effect is seen.

That said most of these kind of tests are done at constant temperatures. The real world fluctuates of course and as temperatures increase organisms can produce 'stuff' (stress proteins, molecular chaperones for e.g.) that help cope with short term exposures to high temps. It makes it difficult to categorically pin down a single thermal point at which the animal is "stressed". This especially if you then add an additional stressor like hooking and playing a fish which can act to lower the upper critical limit to temperatures that the fish would normally cope with in the absence of the extra stressor.

And then you have local adaptation in populations so that different watersheds may have fish with different upper critical limits. Some really neat work has been done on this in Pacific salmon. But the differences are likely too subtle to make any practical difference from a fishing point of view.

Hope that wasn't too tedious a read.

 

[pabrookie94]

They grow faster=less food=cheaper..

 

[JackM]

pabrookie94 wrote:
They grow faster=less food=cheaper..

Whenever I painted for my Dad for extra money, he would always remind me that "paint is cheaper than labor." Rainbows grow quicker, but they only do this by consuming and processing food. The cost of food is the same, to grow to the same size, or closely similar, but it is spent quicker. Meanwhile, the other fixed and variable cost of raising a certain sized fish decreases.

 

[Maurice]

pabrookie94 wrote:
They grow faster=less food=cheaper..

Eh...not necessarily. They grow faster put on more weight and consume more.

 

[JeffK]

My first comment is that comparing the wild Delaware rainbows and stocked rainbows is like comparing apples and oranges. The wild Delaware fish population was established more than 100 years ago and the strain is closer to the wild California fish imported East back then. The stocked rainbow is a domesticated animal that has been subject to breeding for over 100 years to optimize raising in confined spaces, color, angler success and other factors. For more on this read "An Entirely Synthetic Fish." Over in NJ we are seeing more wild rainbows, but they appear to be related to Kamloops trout stocked in clubs rather than the state stocked fish.

The hatchery rainbows are easier to raise and easier to catch and are also the most benign stocked trout for the wild populations. On the easier to catch side, a few years ago NJ stocked a number of streams pre-season with a 50/50 mix of rainbows and brookies. the creel surveys showed a 4:1 advantage for the rainbows. I know the brookies are supposed to be stupider and more adapted to the colder early season temps, but that didn't work out when tested. I go with the data over the scuttlebutt.

 

[pabrookie94]

I guess I didn't think about that side. I assumed they were all fed the same but the rainbows just grew more quickly. Sorry about that