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Old 08-13-2007, 11:45 PM
snaildarter snaildarter is offline
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Default Trout Mortality

Hi All,

With all the talk of high temps, low water, trout death, and Byron's canceled vacation and classes, I wondered if anyone knows of some good, real data showing the relationships of the above. I've no doubt that stressors increase the mortality of fish; I just wonder what the actual numbers are.

I've been googling around this evening, looking for such numbers. Here is what I've found:

- In the Park, 65% of trout die from weather related events every year
- In a study on the Gallatin, of 172 fish that were caught between the temperatures of 45 and 73 F, only one fish died within 72 hours of being caught.
- A study showing Brown Trout growth was maximal at temperatures between 65 and 75 F (the author noted that some other investigators found trout mortality increasing at these temperatures, and he guessed that maybe trout in warmer climates have genes for surviving warmer temperatures).
- Wild trout survive high temperatures better than stockers (duh)
- Lahontan Cutthroats live in relatively hot areas for trout, and have near zero mortality even when temperatures climb to 79 F for an hour a day
- Another study showing about the same thing with Bonneville Cuts

I've heard a lot of talk about rules of thumb like "I don't fish water above 68," but I haven't seen the data to back up a claim like that.

It seems to me, that maybe C&R in these high temps in the Smokies doesn't really cause much mortality, or maybe a better way of saying that is that maybe whatever extra mortality it causes might not be significant when compared with all the other causes of mortality. I've been told by fisheries folk that what limits trout biomass in the Smokies is mostly just the low fertility. If that's true, then maybe killing a few trout simply makes the remaining fish larger, until the next spawning creates more competition again. In fact, without that 65% weather mortality, maybe we would have even more even smaller fish! Maybe fishing 75 degree water in the Smokies is not such an awful thing. Of course I don't really know, which is why I'm asking everyone for whatever studies, or even anecdotal evidence, you can come up with. I think studies done on stockers in tailwaters would not be very relevant, but might still be interesting.

Thanks
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Old 08-13-2007, 11:50 PM
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ijsouth ijsouth is offline
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Good food for thought...and speaking of food, it probably wouldn't be a bad thing to keep a few fish once in a while. Like most people on this board (I suspect), I release almost all my fish in freshwater - in fact, I haven't kept a trout caught in the park. However, I've heard about what happens after a major mortality event, like a flood; the average size increases, while average fisherman catch rates stay about the same. So, some selective harvesting might be a good thing.

Of course, the majority of the fish I catch fall just a bit short of that magic 7 inches, so the point is often moot...
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Old 08-14-2007, 05:51 AM
lauxier lauxier is offline
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Default trout mortality

I started keeping Park trout a couple of years ago because trout caught out of these waters are so good to eat--stockers and farm raised trout do not compare---you would think that Park trout losses of 65%,would be readily observed with dead fish floating up--
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Old 08-14-2007, 08:26 AM
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Rog 1 Rog 1 is offline
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Anyone who has ever fished a farm pond where no harvesting occurs knows the effect....tons of tiny fish.....any water can support only a given number of fish ..... the Park tried to fish out Tremont one year for a brookie experiment....all fish but brookies, no matter the size, were required to be brought out.....could not get all the bows but the result was the next year the average size went up 1 - 2 inches.....after a while things returned to normal and the sizes dropped proportionately.....
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Old 08-14-2007, 09:20 AM
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ijsouth ijsouth is offline
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You know, it doesn't matter what species you're talking about - wild fish taste so much better - much firmer flesh. It even extends to shellfish; Louisiana has had a promotional campaign for the last few years, encouraging people to only buy locally caught shrimp, instead of the farmed stuff from Asia. Now, the promotion is primarily aimed at helping out local shrimpers, who are getting killed by the imports, but it's true - they do taste better.
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Old 08-14-2007, 10:15 AM
CinciVol CinciVol is offline
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I think this is a very interesting topic as well. Is it possible that we could try to put a silver lining on the drought of '07 in that it may "cull the herd" of wild trout in the mountains and result in a period of bigger fish in the coming years just as an increase in harvest might do? Just something I was wondering about as I was driving by the (very) Little River the other day.
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Old 08-14-2007, 04:00 PM
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PeteCz PeteCz is offline
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A very interesting topic. Here is a good study of Trout in Southern California. One point brought up is the variation is what optimal conditions are for trout in other parts of the country (Pacific NW v. So Cal). My guess is that trout here in the Southern Appalachians are closer to So Cal trout than Oregon)
http://www.sce.com/NR/rdonlyres/0FC4...quirements.pdf

The top end of good growth was almost 72 (22C)! and that growth dropped off at 77 (25C).

Maybe we are overly concerned about temperatures. I think the most worrisome aspect of our weather is the drought. I think that has much more to do with stress than water temp.
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Old 08-23-2007, 06:29 PM
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Fishermansfly Fishermansfly is offline
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Default Enough would be enough? If it were enough!

I stated earlier "I'm Done", I'm now retracting that statement. It is disheartening to see a thread started asking questions regarding "in our eyes" a precious peice of what we call home, trout! Wild stream fed trout! The question raised alot of eyebrows and recieved alot of valid points and mere studies! We, those whom have actually taken the time to read the appointed links , hilighting valid points accross the board! I won't throw my opinion in here!

To take everyone back to the original question, yes by quotations!

Quote:
Originally Posted by snaildarter View Post
With all the talk of high temps, low water, trout death, and Byron's canceled vacation and classes, I wondered if anyone knows of some good, real data showing the relationships of the above. I've no doubt that stressors increase the mortality of fish; I just wonder what the actual numbers are.
Let's take a look at the flip side of things and I take it one step further and actually challenge the NPS Steve Moore. There is no possible way to be 100% scientific in the matter! All anyone knows is the actual physical makeup of the fish and what conditions the fish prefer, and even that's loosely stated! We are facing the worst droubt in over 50 years as indicated in previous post to this thread. I'm willing to bet Mr. Moore is only 40 to 50 years old and that this would be the first "BAD" droubt he has seen. The stream side conditions then had to have been better then, then they would be today! For several reasons, also as previously stated on this thread. So how could one person say that they "Know what there doing." Were is this information coming from? I'm sure I'm not the only one out there that is scratching there head! I'm only saying that conditions have obviously changed over the period of 50 years and that any information obtained from then and there after wouldn't be sufficient to come to a physical number today! So how would any one know? Let's further our thinking on this matter. All of these studies are exactly that! Merely a study and nothing more.

So let's propose and actual study! What would be the requirments to fill the very question preposed? I would object to any one's proposel simply due to the fact that there are so many (understatement of the year) factors to be considered and a consistant change in variables! What conditions, what streams, what size of trout, what type of trout, were would the fish be taken from-in relation to the stream, etc. Not to mention an onslaught of variable conditions.

So if a group of biologist got together and did some actual "Studies" which would determine the possibilities of you killing trout.....This would require a person to consider all of those factors before heading to the stream to hook a fish and not feel guilty about doing it. Some would some wouldn't feel guilty! Not to mention that person would have to consistantly check those variables as they proceeded plugging throughout they day! Sound's pretty dumb doesn't it. So I say this to Mr. Moore how do you know what you are doing? I mean this in no negative way, but obviously this question has us all "worked up" so how could you come to that statement? This is by no means any "throat punching to Mr. Moore" I can't stress that enough!

So now back to the common sense issue of this thread....Why, as man, do we consistantly press our luck? It is, in my opinion, that's exactly what we are doing and that someday our resources will be deplinished! So common sense would add that fishing in conditions such as this were the water temperatures are at levels the trout don't particularly care for then why go fishing with the possibility of killing more fish? I say this stricly out of frustration due to the lack of common sense some people have anymore! I see and deal with it on a daily basis!

So I leave everyone with that question....How do you perform a "Study" that would conform to "most" stretches of water in the GSMNP to answer the original question, how does temperature and water levels effect trout?

I'm sure that there are several members of this forum that would be willing to give up some of there time and heart to put a nail in this coffin and help in any "Study" that would conform to a wide variety of circumstances! Count me in, I'm obviously not fishing right now anywho!

Brett
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Old 08-23-2007, 07:11 PM
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ijsouth ijsouth is offline
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The interesting thing is to compare how the different parks are managed, concerning trout. My one other experience with wild trout has been up in SNP in Virginia. There, the fishery is almost entirely brook trout, and the size limit is 9 inches. Also, a number of streams are open for catch and release only, and others are closed outright, and this list of streams changes from year to year. Finally, they seem to defer to the state of Virginia concerning regs, which leads to a very strange scenario....brown trout have moved into the park from state waters below, much like what has happened in the Smokies. SNP wants to eliminate all brown trout from park waters, so any brown trout caught in the east slope streams affected cannot be returned to the water. Ok so far, but here's the twist - it is still illegal to posess a brown trout under 9 inches (in compliance with the state law)...so, any undersized brown trout have to be pitched up on the bank! I was up there in April, and I asked about this...the deal is, the park doesn't really care about the size limit on browns, but the minute you leave park jurisdiction, Virginia can write you a citation for posessing undersized trout, so they put out the advisory that way. Bizarre, to say the least, and a complete waste.
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Old 08-23-2007, 08:39 PM
lauxier lauxier is offline
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Default august

this thread has worn me out---all i can say is--we have found no answers--but--there are no answers in the commotion of these arguments,that commenced as a thread,that will only serve to lead us to---September--the month before october--when rains will fall etc....etc.....M. Twain " when summer rains stop,it gets hot,and when it gets hot,they get hot...
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