Observations on WT Acclimation


John or "LC"
A scheduled trout plant for a local lake at 5400' scheduled for three weeks ago was put in abeyance until December 5. It was not republished, and virtually no one knew about the actual plant. It was confirmed to me with a 100% certainly, along with the exact location, a 3000# plant of triploids in a lake that can easily be completely covered with a pontoon.

Three of us fished the lake yesterday. One had fished the lake dozens of times and knows every holding spot, the techniques, and the flies that work. Another did not know the lake well, and I am somewhere in the middle, having netting around 50 for three previous trips this year.

Between the three of us, we brought three or four fish to net in three hours+ of fishing. Not only was there no one else on the lake, there was probably no one within five miles of our launch site, which was closed. We managed to work around that;-) While fast stripping a streamer is "always" the best technique on this lake, all fish but one were hooked by slow trolling. Locations were very random; there were no particular structure or depth constants.

Lake water temp was 42 degrees, winds were 10-20 mph. The raceway temp in the hatchery from where the fish were taken was 54 degrees. Lake depth ranges from very shallow to 40'. We fished all levels, down to 30', and made several fly changes from streamers to nymphs.

My speculation is our failure was due to the WT being a good 10 degrees below the preferred temperature range of the fish, and that as they had only been in the water for four days, and were not feeding or active because they had not acclimated to the colder temperatures. If correct, this taught us a big lesson in chasing recently dropped truck trout in colder water during the winter.

Would you agree with this speculation?


Active Member
My answer would be yes to your observations!

My father retired on a lake off mount hood where they would plant big brooders every spring. He would wait for two weeks before even trying to fish for these big truck fish (my biggest was 13# out of this lake) I also believe that if the fish are raised in a shallow concrete pond then it takes a long time for them to get used to deep water (air bladders) I would think a good warm front (or at least warmer weather) and a little time and fishing should be better.

Living out of Portland many of our lakes only have the "truck fish" and can be the only game around in the winter for cabin fever. most of our lakes are closed during winter months with any kind of good trout to fish for. even in spring and summer the lakes on mount hood are all managed for put and take "truck fishing" hope next time is better for you!


I also agree with your speculation. I too, will rush the season and try flies when the water temps are flat too cold for planted trout. I get cold but I don't get any fish.

The sudden change from hatchery water temps to lake temps can be a shock to the system of a planted trout and it will take them awhile to acclimate. The good news is if you are there when the rainbow finally do acclimate to their new waters, the fish will go into a feeding frenzy.
I've had decent fishing in lakes with water as cold as 38-39 F. I would agree that it's an acclimation problem. Probably a good idea to time your fishing to include the warmest part of the day when the temps are so low.


Active Member
It is "normal" for trout fresh from the hatchery to remain at about the same depth as the ponds they came from one to three weeks unless the surface temperature is too warm (something in the 60s). Other wise the fish will be in the top 30 inches so you want to fish at that level.

That holds whether the water temp is 40 or the mid-50s. Remember at colder temperatures (upper 30s) the warmest water will likely be on or near the surface. As a result they new trout may remain at or near the surface even longer.

Consistently see anglers that are intune with this behavior doing very well on newly planted waters while those fishing deeper (even a couple feet) struggle for even a fish or two.



John or "LC"
Appreciate the salient responses. I believe the few fish we got were in the top 3-6'. That is usually where we get them year around, and our water temps will range from the high 30s to the mid to high 70s. At water temps above 65 or so we will lose them in lakes with depths over 25' so we only fish those impoundments in the winter and early fall. Spring is bass season in those big reservoirs.

This is highly unusual for this lake to be accessible in December, so it's unlikely we'll have a chance to return until around May when the roads are clear. They will certainly be acclimated as well as powerful hungry by then as this lake, like most lakes on the west slope of the Sierra, is pretty sterile. I think we're going to call it quits for the season in the mid to high elevation Sierra and focus on our lowland lakes, some inland steelies, and of course always Delta stripers.

Jim Wallace

Smells like low tide.
I fished a lake today. River float buddy had a change of plans, and had to cancel. So I headed up to the lake. It was cold, dang slow, and inscrutable. Forgot to bring my sonar, so I didn't get the surface temp, but it felt like under 45 F. Had 6 or 7 hits in 3 hours. Managed 5 hookups: three to the net, all around 14"; one jumpin' LDR; and one 15" - 16" that freed itself at the rim of the net.

Saw a guy cleaning his limit at the ramp, and he was bitchin' about the pale colored meat. Yuk!
On the way home, as I was flyin' over the Elk River bridge, I noticed that Brady's was still open, so I stopped in and picked up some smoked WA caught Albacore and a pint of freshly shucked extra small oysters. Mmmmmmm!
I might no go back to the lake til March.
I like the question and the scenario that goes with it (stillwater guys love a good puzzle :D). I wouldn't argue against that initial shock as the main culprit, but I also think Curt exposed the tip of an iceberg of other considerations. Here are a few more just for fun:
  • Many times newly planted fish will remain near point of entry (i.e. boat launch area) for several days before slowly disbursing and spreading out across the lake; 4 days into it these fish could still have been pretty concentrated.
  • The three hour part stood out as well. In slower/colder conditions a 3 hour outing calls for some luck in terms of intercepting the bite. Plus in the cold both when and where they get active can be pretty isolated at times.
  • On the same note, it's possible when they first start to move and feed it could be in lower light or during the dark.
  • Does the lake support good existing stocks? If they weren't active either, that opens up a whole other set of questions. I'd give that lots of thought and wonder how much can relate to your newer plants. So beyond that initial shock for the planters, would other factors affecting the existing population play a significant role with all fish regardless?
  • I'd be really curious to know what the recent trends were on the lake. Had anyone been out in the prior 2 or 3 weeks? Beyond how the lake was fishing, would be worthwhile to know how rapidly the temp got to 42.
  • Also assuming the ones caught and any other strikes were given a lot of consideration to try and draw repeat business. Sounds like you guys did that. Overall I'm guessing you're on the right track about the new ones, but I'd also consider the simple timing of the bite that day. That three hours probably just fell outside of it.
  • At that altitude I'm sure the lake has some pretty unique characteristics. Can't begin to guess what they all are but I'm thinking a December trip is pretty unusual and solving the puzzle would be tough no matter what. And lack of a recent outing would make it several times harder.
Just saw your comment about December. I was trying to wrap my head around 5400' and this time of year :eek:. Hope you make it back in spring!



Indi "Ira" Jones
Ford, you beat me to many comments.

I can't say that I have exactly experienced the exact same scenario given the altitude, but I have experienced on more then one occasion, recently planted fish into different temperature situations and to be honest there seems to be no exact pattern. At times the fish seem to be immediately ready to eat and at other times lock jawed.

I remember one specific time that I visited an out of the way lake about 4 days after a stocking and I worked the lake hard for several hours. I too approached the lake at the time thinking that the fishing should be somewhat easy due to the recent stocking but after awhile I started to seriously question my ability. Then I found them. It seems that the entire group of recently stocked fish had all moved together about 300 yards to the west of the stocking area and I initially moved to the east. It took me rowing all the way around the lake to find them only just off the launch area. This was also a temp difference scenario from hatchery to a colder lake (albeit a larger lake then you mentioned) but after four days the fish were more than ready to eat. I'd guess that Ford nailed it and the fish were all schooled up together someplace just waiting for the workers to throw them some "pellets".

Jim Wallace

Smells like low tide.
Ahh....feeding time! I think I maybe hit the after-lunch, mid-day nap that the trout take. When I arrived at the lake today, it was about 12:45 pm. The dough bait plunkers at the ramp told me that the bite had been happening for the last 2 hours, but had recently slowed down. Right then, one of 'em hooked up.
No bites...nothing at all... between 2pm and 3pm. Coulda just been my fault, though... me fishing wrong... the stockers just gittin' snooty on me. How does one know for sure? At 3 pm, I started getting strikes again on my trolled bugger in an area with 10 to 15 feet of water. My fly was probably only 5 or 6 feet down, except when I just stopped paddling altogether and let my line and fly sink. I did bring up some weeds from the bottom a few times.
My casting to the submerged woody debris along the shoreline produced absolutely nothing. Maybe I was just doing it all wrong. One hit every half an hour is just too damned slow!


John or "LC"
I I'd be really curious to know what the recent trends were on the lake. Had anyone been out in the prior 2 or 3 weeks? Beyond how the lake was fishing, would be worthwhile to know how rapidly the temp got to 42.
Tim, great responses thanks for your thoughts. The plant was from a small boat ramp, and of course I fished that to the point of flossing it, to no avail. We have found that the trout normally ball up in pods in this lake. we didn't find that to be the case Sunday, but we may have missed them.

From my log: You can see how rapidly the temp drops during seasonal changes at the mid and high elevations. The 19th was a spectacular warm day, and we were being chased by a snow storm on the 21st. We haven't talked to anyone who has fished it recently--doubt many if any have--so this is my most recent info.

10-19-12 XXX Lake

Wx 70s, WT 60, went with xxx, got about 30 between us. Fast stripping, green and brown bugger, point fly not too helpful. Got one 17” Brown on a dry green body mayfly left of the boat ramp.. Fish in shallows to 10'.


Went with xxxx and xxxx, Wx 50s, WT 54, got about 70 between us, VERY shallow area back in the bay. All fish very close to the bank. Cannot strip too fast

Does the lake support good existing stocks? If they weren't active either, that opens up a whole other set of questions. I'd give that lots of thought and wonder how much can relate to your newer plants. So beyond that initial shock for the planters, would other factors affecting the existing population play a significant role with all fish regardless?
No, not really. This is in a chain of small lakes with an inflow from another lake and a small hydro dam outflow into another. It's water supply and hydroelectric, and generally put and take. It's not known for big fish or holdovers and I'm sure this is due to the lack of apparent feed. I've seen some minor baetis and midge hatches at dusk when it's warmer. It does hold some browns, which are natural spawners from several DFG plants a few years ago, but their brown program is gone. An 18" brown is a good fish here, and I've never heard of an 18" rainbow. No tui chubs, shad, or known predators except a couple of Osprey and an occasional eagle. The Osprey wasn't much of a fish finder this time. Just a typical west slope semi sterile impoundment, similar to several on the west slope of the Cascades off Hood.

We normally fish it only after recent plants. We must have passed the hatchery truck on 10-19. The little guys were still schooled up around the ramp and would hit anything. By the 21st they were dispersed but easy to find in the usual spots. I would say most fish are concentrated in 10% of the lake. We never get anything in the deeper water.

We fish it because it's convenient and close to other smaller lakes with some natural spawners. Not a trophy fishery by any measure, but usually not hard to find them if they're there. Oddly, I would guess it's 75% fly fishing. We don't see massive stringers coming out of the lake so we're always curious why some days are just dead. It may be related to the inflow which does fluctuate. This past trip the inflow was strong (always a plus) but the submerged creek bed didn't seem to hold anything.

A point of interest is that the truck fish this year were quite small. I asked the hatchery manager about that and he said he's been disappointed about their growth in the raceways. Apparently they don't grow as fast as the diploids for the first year, then, as we know, they become larger quicker. We are now 100% trips in CA and the jury's out as to the sustaining quality. The private hatcheries supply larger trips to some lakes and they seem to be better than the old DFG diploids.