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| Post Number: 21
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Nose for News 
Group: Members
Posts: 431
Joined: Feb. 2004
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Posted on: Feb. 14 2004,11:21 am |
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Natural Fish Kills
Dead and dying fish are an ugly sight. Truth is, most species of fish are relatively short-lived and have a high rate of mortality. Even large fish, too large to be eaten by predators such as bass and pike, experience a death rate of approximately 50% per year. Fortunately, the deaths are usually spread-out over the year and are rarely observed or become a problem except when concentrated as a "fish kill". The condition called "fish kill" occurs when a number of fish in a given body of water die from a specific cause. Most of the time, fish kills are due to natural causes over which we have no control, such as weather. Only occasionally is death directly related to pollution or improper use of herbicides or other chemicals. Only a fraction of the dead fish are ever observed because many decompose on the bottom or are eaten by scavengers such as turtles and crayfish.
Winter kill
Winter kill is the most common type of fish kill. When severe, it has devastating effects on fish populations and fishing quality. Winter kill occurs during especially long, harsh winters. Shallow lakes with excess amounts of aquatic vegetation and mucky bottoms are prone to this problem. The results of a winter kill are seldom noticed until spring when the ice melts. Then the dead fish, often the larger ones, are seen washing up along the edge. Because they require more oxygen, the large fish suffocate and die first. Winter kill begins with distressed fish gasping for air at holes in the ice and ends with large numbers of dead fish which bloat as the water warms in early spring. Dead fish may appear fuzzy because of secondary infection by fungus, but the fungus was not the cause of death.
Actually, the fish suffocated from lack of dissolved oxygen. Trace amounts of dissolved oxygen (measured in parts per million, ppm) are required by fish and all other forms of aquatic life. Even living plants and the bacteria that decompose organic materials on the bottom of the lake require oxygen. As a rule of thumb, the critical level of oxygen is about 2 ppm for most game fish native to warmwater lakes, and levels below 1 ppm for extended periods of time are lethal.
But species of fish vary in their tolerance of low oxygen. Trout are most sensitive; walleye, bass, and bluegill have intermediate sensitivity; and northern pike, yellow perch, and pumpkinseed are relatively tolerant. Bullheads and certain minnows are very tolerant. Lakes prone to periodic winterkill can often be detected from the composition of their fish populations - tolerant species predominate, sensitive species are rare, and prey greatly outnumber predators. Fortunately, usually enough fish survive, either in the lake or in connecting waters, to repopulate the lake in a couple of years. Only for extreme die-offs is fish restocking necessary.
The dissolved oxygen content of water depends primarily on three variables. These are the amount of mixing with the air above the lake, the rate of oxygen production by plants, and the rate of oxygen consumption (respiration) by living aquatic organisms. During periods of prolonged ice cover, the lake is sealed off from the atmosphere and cannot be recharged with oxygenated air. Furthermore, ice and snow reduce the amount of sunlight reaching aquatic plants, thereby reducing photosynthesis and oxygen production. (During photosynthesis, living plants use sunlight energy and carbon dioxide to make plant tissue and dissolved oxygen). Meanwhile, on-going consumption of oxygen depletes the supply of oxygen stored in the lake when the lake froze over. Shallow, productive lakes are at a disadvantage because they have a low storage capacity and high rates of oxygen-consuming decomposition.
In northern NY, January is usually a critical period and is the best time to check the oxygen content of lakes prone to winterkill. A good midwinter thaw about then often recharges the lake's oxygen supply by means of photosynthesis and melt water. Conversely, a prolonged winter, with continuous snow cover and late ice-out, increases the chance of winterkill.
The only long-term solution for winterkill lakes is to reverse the natural process of filling and enrichment (eutrophication). Dredging or sucking bottom sediments can increase the volume of water, reduce the nutrient-rich sediment, and reduce the growth of nuisance plants. However, such projects are extremely costly, require a site for disposing of the bottom material, and may require a permit. Lake residents can help slow down the rate of eutrophication by keeping all types of plant fertilizers out of the lake.
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DISCLAIMER
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Nose for News Is Pleased To Announce That We Have Absolutely No Affiliation Whatsoever With The Albert Lea Tribune Or Its Parent, Boone Publishing.
Like Other Minnesota/Iowa Residents, We Simply Endure Them.
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| Post Number: 22
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cwolff
Group: Members
Posts: 265
Joined: Aug. 2003
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Posted on: Feb. 14 2004,11:29 am |
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Repdan, the dam is the main cause for poor water quality other than the poorly designed runoff drainage system with high phosphorous levels.
The dam causes higher static water levels, and the water level cannot flucuate lower and higher naturally as needed to revegetate itself. Dams cause the lighter cleaner water to go over the top, while the heavier sediment laden water gets held up by the dam, allowing sediments to settle onto the lake bottom.
With all of the rough fish mostly dead, now is the time for a severe drawdown on the lake to revegetate the lake. The sun light cannot penetrate dirty cloudy water and sediment depths to germinate seeds for the regrowth of vegetation. By drawing down lake levels, the exposed sediments will compact (consolidate) upon itself upto a foot, and the dormant seeds, which will survive for over a hundred years until conditions are right, will be closer to the substrate surface for germination. Yes, you could gain upwards of a foot of water depth by compacting (consolidating) the sediments.
The new vegetation will act like a filtration system by filtering out sediments, nutrients, and pollutants, and provide very important habitat for fish and wildlife. Vegetation will also provide habitat for invertebrates, which is a very important food source for newly hatched ducklings. Winter killing the minnows in the lake will provide ducks less competition for feeding on invertebrates, otherwise minnows can quickly deplete the invertebrate populations within a lake.
Getting rid of the carp and other rough fish will prevent the vegetation from getting rooted up and sediments from getting resuspended causing turbidity.
Last fall the DNR treated Lake Christina with rotenone to kill all of the fish, while targeting rough fish. The last time this was done on this lake, 97% of the lake revegetated, and over 100,000 canvasback ducks stopped over during the next fall migration to forage on the abundant food source.
Now is the right time for Albert Lea to take advantage of the winter kill off of the rough fish. If you leave water levels at a higher static state, you will not get near the revegetation that could occur with a severe drawdown. Act now!
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| Post Number: 23
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MrTarzan
Group: Members
Posts: 564
Joined: Feb. 2004
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Posted on: Feb. 14 2004,11:42 am |
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Yes Clovis it is a dam big problem  Liberal, What would a new dam do? Actually that depends on the dam and accompaning projects. Dredging is one answer, diversion and restoration in the long run is cheaper, they do it routinely out west. Just dig back down to the gravel, (we do have one of the largest gravel bottom lakes in the country) and you create a natural filter again. The problem with dredging is that it just moves a lot of silt around while you are removing bottom. Better than nothing but not efficient. I have attended two different presentations for a great dam design built by a local engineer who really did his homework. He is retired and does not want anything for his design, which the Corps of Engineers is going to adopt for use in other areas, and it will carry away bottom sediment and deepen the lake naturally, especially if the dredging is done. While dredging, and it sounds like that is the decided course by our local committees, you must have excellent flow to maximize the siltage so that it is carried downstream. Then we get the most bang for our bucks. Deeper water with strong flow is far less likely to become suffocating. If I remember my Ecosystem 101 class from college correctly, what is happening to Albert Lea Lake is called eutrification (sp?) which is the filling in of a lake with leaves and natural debris until it is a meadow. However this lake was filled in by man dumping everything from yardwaste and appliances to entire carcasses from the old Wilson plant. Dredging without a new flow control dam won't accomplish much.
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Be not simply good, be good for something-Henry David Thoreau
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| Post Number: 24
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MrTarzan
Group: Members
Posts: 564
Joined: Feb. 2004
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Posted on: Feb. 14 2004,11:46 am |
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Great post, cwolff. Very true in the existing state of this lake.
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Be not simply good, be good for something-Henry David Thoreau
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| Post Number: 25
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jimhanson
Group: Moderator
Posts: 8491
Joined: Aug. 2003
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Posted on: Feb. 14 2004,11:48 am |
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Several friends went down to "fish"--some coming back with huge walleyes--biggest 9 lbs. Just curious--why couldn't these fish be dropped into Fountain lake? Are they too far gone? (The fish taken are still alive). Why COULDN'T these fish be released above the dam, or dumped into an aerator tank before being released? If someone would organize it, I'm sure a lot of people would volunteer--nobody wants to see fish go to waste. Anybody know the answer?
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"If you want to anger a Conservative, tell him a lie. If you want to anger a LIBERAL, tell him the TRUTH!"
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| Post Number: 26
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MrTarzan
Group: Members
Posts: 564
Joined: Feb. 2004
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Posted on: Feb. 14 2004,11:58 am |
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Fish fry at the Salvation Army, everyone welcome,dat's the answer 
Seriously, those things could be done jimhanson, but c'mon, here? First we would have to have a committee, and a study and a outside survey and then it would have to be debated, analyzed and fought over. As soon as the volunteers showed they would start fighting over who should put which fish where and someone would get pushed into the lake. Still, it would be fun to watch all the squabbles.
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Be not simply good, be good for something-Henry David Thoreau
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| Post Number: 27
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jimhanson
Group: Moderator
Posts: 8491
Joined: Aug. 2003
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Posted on: Feb. 14 2004,12:12 pm |
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People will usually cooperate during natural disasters, tornado's, fires, floods--look at all the people that fill sandbags. If the game fish would survive, I'm sure there would be any number of people that would move them above the dam--but it would take a LEADER--someone to take charge, someone that people respect.
Oh, I forgot. Never Mind. 
Seriously, still curious, though, would the fish make it?
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"If you want to anger a Conservative, tell him a lie. If you want to anger a LIBERAL, tell him the TRUTH!"
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| Post Number: 28
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Liberal
Group: Moderator
Posts: 11451
Joined: Aug. 2003
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Posted on: Feb. 14 2004,12:19 pm |
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Jim. It's easy enough to find the answer to your question about throwing them back into fountain lake.
Just go ask your friends with the walleye how they feel about tossing their fish back into fountain lake after they drug them out of the channel.
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The people are masters of both Congress and courts, not to overthrow the Constitution, but to overthrow the men who pervert it!
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| Post Number: 29
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jimhanson
Group: Moderator
Posts: 8491
Joined: Aug. 2003
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Posted on: Feb. 14 2004,12:50 pm |
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I already had asked the question--and the answers were inconclusive--one said he was going to eat his "because he didn't want it to go to waste". The other was the one that said "why can't these be released into Fountain Lake?"
The DNR was present. If they ARE going to completely kill off AL Lake (undecided), why NOT put the fish into Fountain Lake, where the aerators have mitigated fish kills?
It's as though people require "permission" to take action. I don't know that there ISN'T a law against releasing game fish into a lake--but there may be a law against introducing non-game fish.
People have been so conditioned to asking the government permission that they won't take action on their own.
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"If you want to anger a Conservative, tell him a lie. If you want to anger a LIBERAL, tell him the TRUTH!"
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| Post Number: 30
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cwolff
Group: Members
Posts: 265
Joined: Aug. 2003
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Posted on: Feb. 14 2004,1:46 pm |
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Jim, for the DNR to move the fish would require work, and don't forget that it is a little cold out. Also, the pay is the same if they just leave the fish where they are dieing.
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