Trout Winter Kill Questions

[AxeMan]

So, I was recently out at the trout ponds that I have private access to and bad news. Seems that 2 out of the 3 have had winterkill. These ponds are reasonably deep (20 feet +) and have not winter killed in the past 5 years at least. I knew something was wrong even in April through the ice when I observed a lack of activity. I did catch a couple of nice 3 pounders out of the one pond that the fish survived in and witnessed the males trying to spawn in the shallows. I have some questions about winterkill though. I think this this winter has been a tough one on the stocked trout.

One fish I caught had funny looking swollen red gills that seemed to stick out beyond the gill plates; or the gill plates looked recessed. The other one I caught was normal. Is swollen gills a symptom of oxygen deprevation?

Do winterkilled trout stay on the bottom or do they float up? I have seen them dead on the bottom before, but do they stay there and decompose or do they eventually float up?

Another question unrelated to winterkill. I saw a bunch of male rainbows fighting and chasing each other around on a shallow gravel bed. It looked like they were trying to protect a special spot on that gravel bed. Do stocked rainbows actually go through the spawning process and why can't they reproduce?

Spawning Rainbow
TroutSpawn1.JPG

[Nerdapres']

Interesting questions. I'm curious to hear the answers.

The short gill plates can be due to many many factors including oxygen. That defect shows up in hatchery fish as well so i wouldn't say low oxygen is definitely the cause. This is about salmon but it kind of explains it.

http://www.ekoi.lt/uploads/docs/AZL_...-316%20psl.pdf

I've only seen that on rainbows a few times, it occurs a lot more in brook trout on some streams (I'm pretty sure its inbreeding related in those cases, as the genetic pool is pretty shallow for any fish when they got there in a fisherman's bucket 50 years ago).

As for spawning, fish will try even if conditions are marginal. The eggs (rainbow trout in particular) generally won't hatch in standing water as the eggs require good circulation and gravel free of mud and silt. I watched some rainbows trying to spawn on a muddy mix of shale and twigs in a beaver dam last spring, pretty strong instinct to give it a try.

And for winter killed fish, often as they rot (and bloat) some will show up on the surface or washed up on shore. You may see white bellies on the bottom while boating otherwise. Too bad the ponds winter killed, it was a long winter. I'm pretty sure one of my favorite pike lakes winter killed at least partially this year as well. Will take a few years to recover.

[deanmc]

Originally Posted by jrs

As for spawning, fish will try even if conditions are marginal. The eggs (rainbow trout in particular) generally won't hatch in standing water as the eggs require good circulation and gravel free of mud and silt. I watched some rainbows trying to spawn on a muddy mix of shale and twigs in a beaver dam last spring, pretty strong instinct to give it a try.

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Lmao Sorry but reminds me of my younger years. Ive tried that on a beaver dam as well.