A friend wants to get some information on walleye regarding minimum oxygen levels for survival, optimum oxygen levels for growth, and minimum oxygen levels for good growth. etc. for the species. Can anyone help? Seems to me a walleye being in the perch family may be able to tolerate low D.O's, but that is just a hunch.

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Cecil here is the general info. Check your email for more detail.

AquaNic

http://www.seagrant.umn.edu/aquaculture/mn_walleye_culture

Walleye do have some advantages as a culture species. They tolerate a wide range of physical and chemical conditions. This tolerance is related to their natural environment, which is typically large, semi-turbid waters, where temperature and water quality vary considerably. Although they tolerate temperatures between 4¡C (39¡F) and 30¡C (86¡F), walleye grow best between 20¡C (68¡F) and 23¡C (73¡F). Spawning occurs shortly after ice-out in spring when temperatures are between 7¡C (45¡F) and 9¡C (48¡F). They can withstand dissolved oxygen levels as low as three parts per million (ppm) and have been known to withstand two ppm for extended periods in the lab. This hardiness is important because daily and seasonal changes are common in intensive outdoor culture systems.

Cecil -- it seems to me that people worry a little too much about pond oxygen?? Do you know what I mean? Well-managed sport fishing ponds shouldn't have oxgyen problems?? I guess that's overly simplistic, but the walleyes don't care if it is 8 ppm or 12 ppm. Heck, you know that maximum DO can vary that much according to temperature (warm water holds less DO than cold water). So, other than under culture conditions, as Ewest already discussed, they should be ok?

Now, winter oxygen is a very different story!! Yellow perch actually are "tougher" than walleye when it comes to low DO. DO levels can drop below 1 ppm (mg/L) and the perch will still be alive. Walleye generally start to die between 2 and 1 ppm, which makes them "moderately" tough.

I have stated this before, but we don't know as much as we should about winterkill. At times, DO levels seem to reach lethal levels, yet fish don't die. At other times, the DO levels seem ok, yet you get a kill. I suspect it might have to do with accompanying levels of hydrogen sulfide, methane, etc., but that's just a guess. In addition, we have the temperature factor (supercooling?) that we have discussed in the past on the Forum.

Hope this helps!

Rumor has it that there was a study done last year that showed that high winds super cooling the water column plays a major role in shad dies off at reservoirs.

Shorty -- I had not thought of connecting that work to our pond questions, so that was a good idea on your part. I assume you mean Mark Porath's paper??

If anyone wants to see a copy of that study, send me an email, and I can return an electronic file of that paper.

Dr. Willis, I believe it was Mark Porath's paper, my favorite NE G & P biologist, Daryl Bauer, sent me a PM on it earlier this year when I "guessed" that it played a major role in shad die offs. My guess was based simply on a large chara die off at our pond that happened when a strong cold front came through and the winds howled for 3 days super cooling the water on one side of our pond. Temps dropped down into the upper teens and the pond took 2-3 days to freeze over due to the high winds. The massive chara die off then triggered a cold water algea bloom in our pond at ice out. If a strong windy cold front is strong enough to kill chara in 9ft of water, it's probably strong enough to kill some fish as well. I havn't read Mark's paper, but I did hear about it.

I did describe this chara die off on the "Winter Algae" thread back in March of 2006 if anyone is interested.

Thanks guys but i think I should have been more specific. The friend's questions are actually not regarding a pond setting. He is doing some D.O. testing at various natural lakes in the area that are planted with walleye. He's finding some interesting things.

Here's an interesting situation that doesn't seem to be text book, at least I never read about in school... We have a natural lake here about 800 acres. Max depth is 108 feet. The lake is planted with trout and has produced some monsters, including the state record rainbow of 18 lbs. 8 oz. Anyway, the friend has been taking D.O. and temp measurements for the DNR and has confirmed an interesting D.O. profile in the lake which seems to be the norm in this lake. In the second basin of this lake D.O. drops to almost nothing in the thermocline later in the summmer, but BELOW the thermocline starting in 50 to 55 feet of water the D.O. increases again up to 5.0 ppm. This backs up previous data and explains whey we have to go up to 70 feet deep for the trout in this lake in late summer, and can't catch squat in the thermocline even though temps are optimum for the trout. Temps below the thermocline where the D.O. increases again drop into the 40's. Has anyone seen or heard of this phenomenon before? As we all know typically the D.O. gets depleted in the really deep water before the theromocline?

I can only surmise the deeper water has more D.O. because of the colder water? I asked the friend if this layer below the thermocline could be a secondary thermocline and he says no as the temperature profile does not back that up. Conversely a different basin (the first basin) that has the 108 foot hole looses all it's D.O. by later summer.

Cecil, do you know the summertime temps in the deep hole with 5.0 ppm O2?

It's simple. Colder water under pressure will hold more DO. Could also be that their might be some sort of under water or underground flow that enhances the DO in one area and deletes in another.

Theo,

I believe he said temps drop to 43 F. He send me the data as aqn attachment but I can't open it. I'll have to ask the computer whiz wife if she can figure out how to open it.

I'm wondering if there is just such a large reservoir of cold, O2 rich water down deep, with a near complete lack of BOD (like NO plant matter decaying), that the O2 lasts all Summer long. I suspect there is a layer of low O2 water right at the bottom, where the plant matter that has sunk previously IS decaying, but that the pool is so deep it NEVER mixes the bottom with the middle, O2 rich layer. Maybe the bottom stays 39 degrees all year long???

I may know just enough about this from reading Lusk, Cody, and Willis to be dangerous.

Usually no/low O2 in water under the thermocline as no light penetration. It can occur at turnover and last for a while because of low BOD. An exception is where there is a spring / groundwater

Both lake basins will at or below the thermocline will be exposed to very close to the same pressure since both hypolimnions begin at very close to the same depth in two basins of the same lake.
Underground cold spring water is usually low in DO.


Here is what I am pretty sure is happening and it is not all that rare of an occurance in very deep lakes that are marginally oligotrophic and bordering on mesotrophic. (Look for Bob Lusk's and my article about trophic types of lakes and their general physical conditions in the Nov-Dec 2007 Pond Boss magazine.)

The basin that holds hypolimnetic deep DO is slightly less eutrophic than the other basin. MORE dead plankton rain out and more suspended organic particulates occur and settle in the basin that loses the DO (see below). In lakes with human activity it is not uncommon for one basin to be measurably more eutrophic (due to human activities) than another basin in the same lake. Overall it depends a lot on numerous conditions.

When the sedimenting organic particulates reach the cold thermocline, their sinking rate abruptly slows and they tend to accumulate when they reach the cold layer which is significantly more dense. As accumulations build up, the DO gets consumed (biological activity) more rapidly compared to other zones with fewer organics. Thus a band of water in the region of the thermocline gets depleated of DO whereas the deeper water that does not receive the influx of organics remains oxygenated longer than water above it.

In the basin that loses the DO the loading of organic particulates is greater (more eutrophic) than the other basin. Higher amounts of the settling organics manage to overwhelm the accumulating layer of cold water organics and enough settle through the thermocline into the hypolimnion to cause enough DO loss in the hypolimnion to gradually depleate the DO as summer progresses. Also, morphology of the two lake basins may be different enough to affect the depth of the thermoclines and the temperature profiles. Also seiches may play a role in rate of the accumulating organics and their behavior and their settling rate though the water column.

BC hits nail on head. all of our lakes (reservoirs) in northern CA exhibit this phenomena. they are oligotrophic or marginally oligotrophic. in mid-summer, it is common to find trout holding in the submerged river channels at depths as great as 300 feet in water w/ cold temps, low BOD, and adequate year round DO levels. fishing for them is quite a challenge.

i'll let y'all know how the eagle lake trout fishin went when i get back later next week....eagle lake is not one of our deeper lakes, and it is supposed to just now be turning over, with trout coming back up to forage near surface.......i cant wait.......

HI Cecil, The Walleye culture manual will help anyone a lot, even if they are not helpable! New word!

What do you do with all of those wheelbarrows of aquatic vegetation that you pull out???

What do I do with all those wheelbarrows of aquatic vegetation? I have a tall weedy area on the dike of my biggest pond facing the highway where I dump them and allow them to dry out and disintegrate.

Bill,

Makes sense to me. One things that leads credence to your explanaton is the the first basin has all the inlets which may be bring in in lots of nutrients. And the first and second basin are seperated by a extensive area of shallow water.

Cecil,
And I assume that the basin with the inlets and likely more eutrophic conditions is the one that loses the DO in the deep zone. Correct?

Correct!