how hot is too hot?

[JackM]

Chaz
Re: how hot is too hot? #7

68 degrees, please cary a stream thermometer.

Posted on: 2006/8/28 14:39

salf2
Re: how hot is too hot? #6

All,
this is all very interesting and the info i have been looking for any tips on trout behavior or biological info most appreciated! Judgeing from the Yellow Breeches Brown trout seem to b the most adaptive as we all know the creek gets quite warm in the summer and due to the lack of rain as of late i have left well enough alone! Helping to stock alot i have found that our preseason Brook stocks are great when water is cool but they disapear shortly thereafter not only from being taken but the breeches warms and you no longer see Brookies! through the hottest summer months it is not even viable to fish but alas we have got some rain and the water has cooled alot ! Browines are the only ones hardy enough to have survived this so called drought as i have seen!

S,

Posted on: 2006/8/27 11:15

JackM
Re: how hot is too hot? #5

I think the "rule" about not fishing if the water temps are over 70 degrees is a good rule, but it only tells part of the story, as snerd's post suggests. The "lethal limit" for Rainbows brown and brooks respectively are (if I'm recalling correctly) 76, 77 and 78 degrees F. This lethal limit means if the water remains at or above those temps for 48 hours, the fish will die, period. It is also true that above 70 all 3 species are experiencing some level of stress. Many streams experience temperature fluctuations of as much as 10 degrees or more in Summer, going down into the 60s at night and into the 70s in the day. If they are peaking for a couple hours at 72 degrees, but maintaining sub-70 temps for 18 hours, I would be willing to bet that incidental mortality of trout caught even at the peak temperature period is not much greater than otherwise. On the other hand, if the stream is staying in the low 70s for 12 or more hours a day for a couple of days or more, the incidental mortality of fish caught even during the coolest periods would be significantly greater than otherwise. The stress producing effects of temperature come from two sources-- dissolved oxygen levels and also blood temperature. The trout's body temperature is that of the water, being "cold-blooded" creatures. At a certain blood temperature level, certain chemicals are secreted which have a preservative effect on tissue, but also weaken the fish considerably. There is a recovery period needed when those chemicals stop being produced. This is why the ultimate peak temperature reached and the period it is sustained is important to take into account.

How do I know this? I researched it many years ago when I caught hell for fishing Yellow Creek when the mid-day waters were temping at 72F.
_________________

Posted on: 2006/7/30 13:53

snerd
Re: how hot is too hot? #4

Quote:


Brook trout can tolerate relatively acidic waters, but not temperatures much over 65 degrees.

A brown trout’s optimum water temperature range is 50 to 60 degrees, although it can tolerate water temperatures in the low 70s.

The statement that brook trout cannot tolerate temps much over 65 degrees is way off. Many brook trout streams go into 70s nearly every summer. They can survive at least up to 79 degrees. Brown trout also, won't typically start to croak until above 80. A lot depends on dissolved oxygen levels of course. Of course you don't want to fish for trout at these extreme temperatures. I'm talking about survival temperatures.

A good cutoff temp for trout fishing is 70 degrees. When it hits 70, quit. Go the river and catch smallmouth.


Posted on: 2006/7/29 20:02

live2fish
Re: how hot is too hot? #3

This was taken from the PFBC web site.
Brook trout can tolerate relatively acidic waters, but not temperatures much over 65 degrees.

A brown trout’s optimum water temperature range is 50 to 60 degrees, although it can tolerate water temperatures in the low 70s.

Rainbows do best when the water is under 70 degrees, they can withstand temperatures into the 70s if there is plenty of oxygen and a cool, shady place to which they can retreat.

75 degrees for browns and rainbows. 65 dgrees for the brooks.

Posted on: 2006/7/29 19:25

Maurice
Re: how hot is too hot? #2
Moderator

Golemz

Trout begin to exhibit stress at around 68 degrees. Adding undo stress above that temperature increases their probability of dying at an exponential rate. For instance, if the water temperature is 68-70 degrees and you play them quickly, they will likely survive.
as you get above 70 degrees the longer you play them the the more likely they will perish. and the higher over 70 degrees the shorter they can handle the additional stress.

If you fish for trout in water temps over 70 degrees plan to keep the trout or they will likely die.

HTH,

Maurice

Posted on: 2006/7/29 19:12

golemz
how hot is too hot? #1

I'm sure that this is going to sound stupid to most of the experienced guys, but i'm not very experienced in trout fishing. At what water temperature should I not fish for trout that I wish not to harm? I've heard 70, 72, and 75 fahrenheit. Can anyone clear this up for me because I really want to do the right thing.
thanks

Posted on: 2006/7/29 18:44

 

[Chaz]

All you need to know is that trout start getting stressed at 68 degrees. Above this temperature they start having trouble maintaining their weight. It becomes hard for them to breath and the oxygen content in the water starts to drop.