Fishing in British Columbia > General Discussion

Interior Lake Winter Kill

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clarki:
Winterkill is normal, natural, and not unexpected, occurrence in the artificial fishery that we have created for ourselves.

While the Kamloops trout is native to some lakes in the region, the provincial fisheries/hatchery program has stocked trout into lakes where they didn't exist prior, has propagated various strains of trout outside their normal range, has genetically modified fish to maximize growth, uses artificial means to support fish populations, and builds structures to create/sustain fish-supporting bodies of water.

It's an artificial fishery that wouldn't exist without tax dollars and license fees.

Low dissolved oxygen in interior lakes is normal, natural, not unexpected, and has been happening for many hundreds of years. It just becomes a tragedy when it shatters the hopes and dreams of thousands of stillwater anglers and represents a loss of hundreds of thousands (millions?) of dollars worth of hatchery stock.

The province has created a world class fishery that is a significant economic driver. This isn't meant to be a criticism of that. But let's face it...it's a largely artificial fishery propped up by millions of dollars of annual investment and winterkill is a natural occurrence that impacts an unnatural process.

Caveat: a bit of a troll post, but I believe most of it :)

RalphH:
You are quite right there is little natural about most of the popular Interior locales but our south coast fishery is also pretty much an artificial fishery. Plus the fish are subject to a long list of hazards both natural and human created. Many more of the stocked fish in interior lakes grow to a good size while these days we known something like 2% of hatchery salmonids do. That's a pretty limited payback. 

SuperBobby:
I'm not sure I've ever witnessed such an intense heatwave (as the one we are about to start) within a few days after iceoff.
My question is does anyone know if this will speed up turnover or does it make it worse. I would say it should speed it up but I'm not sure.

RalphH:
 https://northernwoodlands.org/outside_story/article/lakes-spring-back-to-life


--- Quote ---The density of water changes with temperature. We know that 212°F is the boiling point for water, and 32°F is freezing. A third significant number regarding water chemistry is 39°F – the temperature of maximum water density.

In the fall, a lake cools until it reaches a uniform 39°F. As the lake continues to cool it becomes stratified – the heavy, 39°F water stays on the bottom, while the water near the top is chilled by the below freezing air temperatures. Ice, less dense than water, forms when the lake’s surface temperature reaches 32°F. The ice acts as a barrier to wind, which prevents the lake water from mixing; it also inhibits the lake’s exchange with oxygen in the atmosphere. Once a lake is frozen, the depletion of oxygen by the lake organisms begins.

Just when the lake’s oxygen supply is nearly exhausted, spring arrives and the ice cover slowly melts, exposing the surface to warmer temperatures and vigorous vernal winds. The lake’s surface water begins exchanging gases with the air. When the surface water warms to 39°F, it sinks, pushing through the deeper water and infusing it with oxygen. This process creates a powerful convection current that continues to churn until all the lake water is an even 39°F, top to bottom, and the water has reached its oxygen saturation point (approximately 12 parts per million).
--- End quote ---

so if the top layer of water is less than 39 degrees  a number of hot days may it speed up.

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