Trout and high temps?

[Troutmeister]

From fishing a local creek (Jordan) over the years I know the trout don't survive the summers. For the last couple of weeks the temps have hit the high 70s most days with a few days over 80*. I started fishing for bass and panfish and to my surprise the trout are still actively feeding. Yesterday I was out and caught some bass and panfish and 4 trout, water temp was 75 or a little more. Last week was the same.

The consensus from the members here are that they stop feeding in water that warm and they should be either dead or looking for relief near a cold water source. I haven't found that to be the case. They seem to be in deeper pools the same place they've been all season. What gives, and how long of a prolonged heat spell do you think they can take before going belly up?

 

[redietz]

From fishing a local creek (Jordan) over the years I know the trout don't survive the summers. For the last couple of weeks the temps have hit the high 70s most days with a few days over 80*. I started fishing for bass and panfish and to my surprise the trout are still actively feeding. Yesterday I was out and caught some bass and panfish and 4 trout, water temp was 75 or a little more. Last week was the same.

The consensus from the members here are that they stop feeding in water that warm and they should be either dead or looking for relief near a cold water source. I haven't found that to be the case. They seem to be in deeper pools the same place they've been all season. What gives, and how long of a prolonged heat spell do you think they can take before going belly up?

They don't stop feeding; they just can't survive being caught at those temps. There's a difference. A few years back, my biggest trout of the year came by accident while I was SMB fishing in near 80 degree water.

If you're fishing with the intention of keeping your catch, and never lose a hooked fish have at it. If you're planning on releasing trout, avoid fishing in warm water.

 

[Mike]

I take it that you are not near a trib so the only other thing that I have noticed is that in the lower Jordan there are some limestone bedrock crossings of the creek and this means that there could be springs associated with that geology. I once measured lower stream temps by a degree or two within and below those crossings. It is likely that there are areas where groundwater is coming up from the stream bottom, which could occur in pools. Under very low flow conditions there is less energy to mix cold (more dense) and warm water, so the flow from any cold water source might have a better chance to stay intact in source pools or settle into near-by pools, which means that perhaps the pools where you are catching trout MIGHT be a bit temperature stratified. Otherwise, I am surprised that trout are feeding at 75 deg F.

I should add that I once used my hand to discover a substantial spring emerging from gravel within an otherwise warm riffle in Willow Ck, a Berks Co stream. There was no visible sign of the spring. The trout population, however, led me to the general vicinity of the spring, but even in this case the trout were not concentrated around this spring; they were normally distributed in habitat below that spring and other near-by springs.

In 42 yrs of fieldwork on wild and stocked trout streams I never found an instream spring or a concentration of trout around an in-stream spring. I saw one pic, however, from the West Branch of Perkiomen Ck in Montgomery Co where a group of perhaps a dozen wild Browns was tightly concentrated into a “ball of fish” directly within and around a center channel in-stream spring. Again, this is very unusual in Pa. It is not unusual, at least in early summer, to see trout at the mouths of tribs or at small springs emerging from stream banks. The vast majority of these fish probably don’t survive the summer due to predation, depleted energy, and shrinking refuge sites as surrounding stream water warms.

I can’t explain your capture of trout if the temp in the micro-habitat where the trout were located was 75 deg. They should not have been feeding, although when the stream temp falls at night they may actively feed, but often not taking in enough food to make up for weight loss during the warm periods related to high metabolic rates and low forage intake.

 

[afishinado]

In 42 yrs of fieldwork on wild and stocked trout streams I never found an instream spring or a concentration of trout around an in-stream spring. I saw one pic, however, from the West Branch of Perkiomen Ck in Montgomery Co where a group of perhaps a dozen wild Browns was tightly concentrated into a “ball of fish” directly within and around a center channel in-stream spring. Again, this is very unusual in Pa.

^ I've seen this happen a long time ago on Fishing Creek, the Columbia County one, in the FFing stretch (at that time) at Grassmere Park. Many trout (dozens) were all stacked in a hole like cord wood. Looking back I should have taken a temp reading there as well as other areas to see the temperature variations causing the trout to huddle up in one hole.

 

[Swattie87]

This does happen. Not with great frequency but if you wet wade WW creeks that flow through Limestone belts in the Summer (Conodoguinet or Swatara for example) you can find obvious small localized springs emerging. Your ankles will go ice cold. I’ve never found Trout stacked on these, though, there aren’t many (any?) resident Trout in the lower reaches of these streams outside of pretty well known trib mouth areas. The one in particular on the Swatara I’m thinking of is in a shallow gravelly riffle, with no tribs immediately near by. There’s one perhaps a 1/4 mile downstream.

In NC PA you will see Trout stacked at the tiniest of trib mouths in the Summer on the big streams. Sometimes the tribs appear to be completely dry, on the surface at least, but there is clearly a small volume of water flowing subsurface and entering the larger creek prompting the fish to congregate there. There is definitely a pecking order to it. The biggest fish are up front holding stationary with their nose pinned to the seep. Smaller fish are behind them, jockeying for position for the coolest leftover spots. They won’t spook even if you stand right over for them. DO is all that’s important to them. The Herons I’m sure have a field day with this.

 

[JeffK]

One problem with many springs is that the water coming right out of the ground may be short of oxygen. Therefore, need to mix in a little stream water or travel some distance to dissolve in some oxygen.

There are commonly springs in Eastern PA/western NJ where a limestone deposit meets an impervious gneiss deposit. Where this happens in the Delaware R near Reigelsville trout used to congregate in summer.

It seems to me that some stocked trout often seem to do OK in warmer water. Many stocked streams I fish I actually prefer smallmouth fishing in the summer with Senkos. I'm always surprised how many trout I catch when I am targeting smallies. Last summer it seemed I was catching trout in smallmouth water until hurricane Ida screwed everything up. Some stockies seem to get paler and thinner over the summer and vanish and others seem to do OK. Who knows why.

 

[lycoflyfisher]

I think it is important to separate stocked trout and wild trout when discussing thermal stress, behavior, ultimately angling ethics.

1 if you are interested in harvesting fish and are targeting stocked trout, who cares what the water temp is. Obviously in warmer temps the fish typically are not actively feeding, however I have had some tremendous dry fly action in that magical last 30 min of daylight on large Freestone streams through July when water temps have been well into the 70s.

2 if you are targeting wild fish and planning to release your catch, certainly use a thermometer and fish accordingly.

3. I think that wild fish are much more adept at surviving periods of thermal stress than we give them credit for if they can find well oxygenated water.

 

[silverfox]

Last week a buddy and I were fishing for panfish in a local lake and he told me about seeing a bunch of trout in a local stocked stream that gets extremely warm. We stopped by after fishing the lake and I proceeded to catch 5 stocked rainbows in the stream (along with a bunch of chubs and fallfish). They ate a small white cork popper off the top that I was using for panfish and fought surprisingly well. They were all in good shape visibly anyway.

I didn't have a thermometer with me, but the water had to be in the mid to upper 70s. It felt like bath water. They were in a deep pool, and I'd be very surprised if there's a spring seep anywhere near this place. Several miles downstream there are some spring inputs, but not up where this was.

I know of another place another buddy found recently where every stocked trout within 50 miles (trout aren't stocked in the big river, but several nearby tribs are stocked and get warm) must have ended up at this coldwater mountain stream mouth to a large warmwater river. Now they've spread up and down this little brook trout stream and congregated at the mouth in the big river. Hundreds of them.

I personally think (completely anecdotally) that those fish that survive past the initial trout season opener probably survive much longer than most people think, and more survive than simply die from the heat. In some cases/places anyway. I think especially where they're stocking directly below a Class A boundary. If they're swimming miles in warm water to find refuge then swimming a few hundred yards upstream isn't much of a challenge. They may be genetically inferior and labeled as "unfit" for survival, but they're still animals and animals have a strong will to survive.

 

[Tigereye]

This does happen. Not with great frequency but if you wet wade WW creeks that flow through Limestone belts in the Summer (Conodoguinet or Swatara for example) you can find obvious small localized springs emerging. Your ankles will go ice cold. I’ve never found Trout stacked on these, though, there aren’t many (any?) resident Trout in the lower reaches of these streams outside of pretty well known trib mouth areas. The one in particular on the Swatara I’m thinking of is in a shallow gravelly riffle, with no tribs immediately near by. There’s one perhaps a 1/4 mile downstream.

In NC PA you will see Trout stacked at the tiniest of trib mouths in the Summer on the big streams. Sometimes the tribs appear to be completely dry, on the surface at least, but there is clearly a small volume of water flowing subsurface and entering the larger creek prompting the fish to congregate there. There is definitely a pecking order to it. The biggest fish are up front holding stationary with their nose pinned to the seep. Smaller fish are behind them, jockeying for position for the coolest leftover spots. They won’t spook even if you stand right over for them. DO is all that’s important to them. The Herons I’m sure have a field day with this.

Saw this on the Lackawaxen. Fish were nose to the bank at a small spring seep entering the water. Probably 30 fish or so stacked fin to fin.

 

[Fish Sticks]

You can see every year on the Allegheny looking down from a bridge a mile or so downstream of the city of culvert…I mean coudersport.

 

[Troutmeister]

Relax guys, these are stocked trout that won't make it much longer. I wouldn't fish for wild fish in these temps. There are not too many cold water tribs on the Jordan, by the way, not fishing the lower section. I am aware of some springs and limestone influence in the lower Jordan but I am a few miles upstream.

I will keep any trout caught from such warm water only because they will probably die anyway. Just posted because I was surprised that they are still eating and surviving. By the way I saw several today including 2 goldens and a rainbow at least 20". I hooked that rainbow twice this spring and lost him both times. I hadn't seen him since then, but the water is so low now that I could easily see him, same hole where I hooked him this past spring.

 

[sarce]

Had a stocked rainbow chase a bugger repeatedly in 76 degree water last week. Is it possible that after a week or two or three of not feeding much due to thermal stress, they are so hungry they abandon all the "rules"? That's what it always seemed like to me when I catch a stocked trout by accident in the summer.

 

[Swattie87]

Relax guys, these are stocked trout that won't make it much longer.

The two biggest I saw a couple years ago on Pine at the mouth of the dry trib, seemingly in its seep were really good looking Browns. Easily could have been wild. Or Slate Run stockers too. Who knows.

 

[Mike]

Hassen Ck and Mill Ck, both tribs to the middle Jordan, temporarily attract stocked trout to their mouths in early summer, but the fish disappear by mid-summer. I’ve watched them struggle to maintain position on the edge of the pods and then lose equilibrium, drifting downstream to die.

When on the rare occasion I heard of a sizable number of stocked trout appearing at the mouth of a cool trib in early to mid-summer in general regulation stream section, I cut the section allocation accordingly. Such occurrences are a waste of stocked trout that could be better utilized elsewhere.

As for wild BT out-competing wild ST for thermal refuge areas, I’m not buying that as a common occurrence in Pa. If it were so, then electrofishing would reveal pods of wild BT assembled around said former ST refuge areas and, as I said earlier, that is a rare occurrence in Pa.

 

[Dave_W]

I've had trout take bass flies in water temps in the upper 70s, but this is rare.
I do see trout feeding much more frequently in water temps in the low 70s.

I'm still taking a creel with me on local creeks while targeting sunfish and will creel any stockies I can catch but this time of year is usually the end of the line for the many stocked fish that were still in the streams at the end of June. Turtles gotta eat too.

Swattie: I have noted the same cold spots while wet wading in CV streams - Breeches has some of these. The change in temps is quite noticeable, especially when water levels are very low. Such spots are non-existent as far as I can tell in Adams Co., which of course lacks Karst geology. I have not seen groups of trout stacked on these mid-channel springs, but have always assumed that the fish related to them in summer. I have heard accounts of mid river springs holding trout in the Susquehanna in summer, but I have never felt such cold water while wading the Susky.

 

[Swattie87]

Swattie: I have noted the same cold spots while wet wading in CV streams - Breeches has some of these. The change in temps is quite noticeable, especially when water levels are very low.

Agree, they’re most noticeable when flows are low. They’re not big, like dinner plate size, and they’re easy to miss. You literally have to step on them to notice.

Outside of karst regions I think the mechanics are different. Stream beds may look dry, or flowing only marginally on the surface, but there is water in the water table underground, and that water is much colder than any water on the surface. Why you see fish stacked at trib mouths on Pine for instance even when the trib is dry at its mouth, or only flowing with a trickle of 70 deg water on the surface. I have good evidence to suggest fish huddle at these spots during the day, and then spread out and feed at night and in the early morning when temps in the main flow are lower.

 

[Fish Sticks]

Invasive trout species pushing native brook trout out of thermal refuge is one of the most well documented mechanisms of harm, out of the multitude, we have seen in the literature.



Dr. Kurt D Fausch first demonstrated brown trout displace brook trout from prime in stream habitat in 1981.

https://static1.squarespace.com/static/5ade84b245776e718e5f0ed4/t/5dd1c78bb9f8cf5cdf8b7ca5/1574029197444/Fausch+and+White_Competition+between+brook+and+brown+trout+for+positions+in+a+michigan+stream.pdf

-then brown trout impairing brook trouts use of thermal refuge clearly demonstrated in experimental setting by Dr. Hitt. He hypothesizes that removal of BT would allow downstream expansion of brook trout in many cases depending on the spacial confoguration of thermal refuge.

Brook trout use of thermal refugia and foraging habitat influenced by brown trout

NP Hitt, EL Snook, DL Massie, Canadian Journal of Fisheries and Aquatic Sciences, 2017 - Cited by 54

scholar.google.com

-then this concept of brown trout and rainbow trout displacing native brook trout from thermal refuge was demonstrated by Trego et al’s 2019 study that utilized snorkeling surveys in shavers fork in WV.

https://onlinelibrary.wiley.com/doi/full/10.1111/rec.12925

-then Brock Huntsman et al. In 2022 studied competition on habitat use between native brook trout and brown trout on stream improvement reaches. It concluded native brook trout listed as target species for stream restorations cannot benefit from stream restoration if invasive brown trout are present and the restoration can likely give the invader the upper hand to displace them in many cases.


In Michigan Hoxmier and Deiterman Removed brown trout from Coolidge Creek and the brook trout population did in fact immigrate downstream and use the larger waterways when brown trout were gone as suggested by Nathaniel Hitt’s exerimental findings of brown trout impairing brook trout use of thermal habitat.

I don’t know If fisheries scientists can say anything more confidently about brown and trout brook trout interactions as a whole than the fact that browns push brook trout out of prime habitat features at fine scale including specifically thermal refuge. It could be the single most scientifically supported conclusion I’ve seen in fisheries science research examining negative effects of invasive brown trout on brook trout.

I would say that obviously the observation of not seeing them replaced at thermal refuge survey to survey is not hith quality data compared the above. These studies control for variables/confounders in many cases and are carefully designed.

Your electro survey observations of not seeing brown trout replace brook trout at thermal refuge sites could be due to the fact that where you see brown trout only Brook trout have already been displaced. And where you see brook trout only I could imagine there would be a number of reasons brown trout have not yet displaced brook trout in certain locations. However, i have to say we all know streams where brown trout have almost completely displaced brook trout recently(relatively speaking). If you took segloch run for example obviously brook trout appear to be on their way out there on a completely forested stream with spring influence on SGL. You would have to see the change of species composition occurring at sites of thermal refuge in a stream like that if noticeable displacement is actively occurring. Segloch is anecdotal as far as I know but personally experienced and seems obviously a case of displacement. However, point is displacement is happening in Pa we know this this includes thermal refuge in streams where displacement occurs.

 

[Dave_W]

Outside of karst regions I think the mechanics are different. Stream beds may look dry, or flowing only marginally on the surface, but there is water in the water table underground, and that water is much colder than any water on the surface. Why you see fish stacked at trib mouths on Pine for instance even when the trib is dry at its mouth, or only flowing with a trickle of 70 deg water on the surface. I have good evidence to suggest fish huddle at these spots during the day, and then spread out and feed at night and in the early morning when temps in the main flow are lower.

Agree.

 

[Fish Sticks]

Agree, they’re most noticeable when flows are low. They’re not big, like dinner plate size, and they’re easy to miss. You literally have to step on them to notice.

Outside of karst regions I think the mechanics are different. Stream beds may look dry, or flowing only marginally on the surface, but there is water in the water table underground, and that water is much colder than any water on the surface. Why you see fish stacked at trib mouths on Pine for instance even when the trib is dry at its mouth, or only flowing with a trickle of 70 deg water on the surface. I have good evidence to suggest fish huddle at these spots during the day, and then spread out and feed at night and in the early morning when temps in the main flow are lower.

As you mentioned water can still be flowing in the hyporrheic zone below the stream bottom and its colder. Swatty you and I have probably seen the same manhole sized spring demarcated by sand in low flows in Hummelstown. Have never seen fish huddled around that one but habitat around it is kinda featureless.

 

[McSneek]

I caught my biggest stocked trout of the year in the Conestoga River of all places last week. I thought I had a huge smallmouth on then when it took off downstream I thought maybe channel cat or carp. I was shocked when I got it close enough to see the telltale pink stripe. It ate a #4 woolly bugger that I think is a nice crayfish imitation. It fought like a steelhead. The ‘stoga is bath water warm. Go figure.