Allatoona DO and Temp. Profile Date

[Jim Hakala]

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We (DNR) conducted our annual August measures of water temperature and dissolved oxygen (DO) profiles at Allatoona yesterday. Like most years, DO was unsatisfactory for long term fish inhabitance at depths below 27 ft. This means the fish in Allatoona are generally restricted to depths above 27ft where there is suitable DO levels. However, unlike any other year since 2001, water temperatures from the surface all the way down to 27ft. ranged between 86-88 F. These temperatures are very stressfull to striped bass (acutely lethal in some instances) - a cool water fish species. These high water temps. are also hard on hybrid striped bass and spotted bass caught and released by anglers. In light of the current water temp. conditions, undoubtedly a function of the oppressive heat wave this summer, I offer the following recommendations/suggestions to help reduce mortality of fish caught and released at Allatoona over the next several weeks.

1) Keep the play and landing of striped, hybrid and spotted bass to a minimum by using heavier tackle (ex. fishing line, reels and rods) that will allow the fish to be brought in quickly.

2) Keep handling (ex. hook removal, photo ops, and retention of fish in live wells) to a minimum or avoid the latter all together.

3) Try to keep fish in the water when removing the hook and keep the time out of the water for others to a bare minimum before release.

4) Morning and evening fishing will avoid handling fish during the hottest times of the day.

These water conditions will likely persist well into September when air temps. begin to moderate.

Thanks,

Jim

[wcbassfisher]

Great information Jim really appreciate what you guys do.

[Bob Smith (Porko)]

Thanks, Jim, That is valuable information! Wally and talked to a guide on Guntersville the other day that told us he sometimes dives in to cool off during the hot summer days. He said he can easily dive to 20' and he had done so the week before we fished with him. He said there was no noticeable difference in the water temp as far as he could dive. Your report is probably true over there as well!

[leapnlineman]

Jim did the DO levels or temp variances denote a thermocline, if so at what level was it? Are you compiling a graph of those measurements at various water depths as you did in the past?

[Bob Smith (Porko)]

Aug 18, 2010 21:34:22 GMT -1 leapnlineman said:

Jim did the DO levels or temp variances denote a thermocline, if so at what level was it? Are you compiling a graph of those measurements at various water depths as you did in the past?

Ray, I think a fairly educated guess would be 27'. The other question I have is since the normal gradual drop in temps till you get to the Thermocline isn't present is whether we should be fishing for anything above 27'. Those fish must be extremely stressed!

[pbmang]

Aug 18, 2010 21:34:22 GMT -1 leapnlineman said:

Jim did the DO levels or temp variances denote a thermocline, if so at what level was it? Are you compiling a graph of those measurements at various water depths as you did in the past?

You can start to see the thermocline pretty good on your graph right now. According to Jim, at the dam it is around 30 ft. It seems like around Victoria I was seeing it around 28 or 29 ft, but it's been a few days since I was on the water. I guess that would agree with Jim's assessment of 30 ft since you figure the transducer is ~ 1ft. in the water.

Here is a quote from Jim from a similar question:

At the dam location, water temp at the surface was 88.5*F and was 86.4*F at 27 ft. The thermocline started around 30ft. down. At 50 ft. the water temp. was 77*F, but the DO was nearly 0.

[chase <ºj))))>< <ºj))))><]

I feel sorry for the fish (seriously). If we are going to keep taking a picture when we catch them, maybe we should jump in the water with the fish, and take the picture with an underwater camera. I'm only half-way kidding here. -- I see floating stripers and hybrids all the time all over the lake. Maybe a few of them were killed by boat propellers, but I'll bet quite a few died from being out of the water too long for an angler's photo op. I confess I've been guilty of this myself. -- Just thinking out loud here... but if we had nets with a 2' ruler built in along one edge, maybe we could keep the fish in the water (in the net) and try to position the fish in the net so that we could take the picture that way. That would at least give us some idea of length without having to remove the fish from the water... what do you guys think? Would that work?

[chase <ºj))))>< <ºj))))><]

HA! RIght after I posted the above, I Googled "Measure Net" and found this on the Bass Pro Shops site: "The Measure Net is the only landing net that allows you to catch, measure, and release fish without ever actually touching them. Simply land the fish in the net, and then add the numbers at the head and tail to get the total length. Example: If the number at the tail is 8 and the number at the head is 10, the total length of the fish is 18 inches. Features a black aluminum frame, stretch strap, and nylon mesh basket with built-in ruler. Large net features a telescoping handle." It's here: www.basspro.com/webapp/wcs/stores/servlet/Product_10151_-1_10001_65564____SearchResults Costs $30

[Jim Hakala]

I couldn't post the graph, but here is the table of the data collected on 8/17/10 in front of Allatoona Dam. It is unfortunately compressed making it difficult to read. The first depth is 0.2ft. Temp is 88.5*F and DO is 6.42 mg/L and so on. The thermocline (defined: rapid change in temperature with increasing depth) beigns somewhere between 24 and 27ft.

DO or "dissolved oxygen" levels are lethal, over a short exposure period, to most fish at levels <1.0 mg/L. These data indicate that fish in Allatoona can not stay for any extended period at water depths greater than 24-27 ft. Fish will chase bait below this depth, but they can not remain their indefinetely. It would be like you holding your breath underwater in a swimming pool. You can do it for a while, but you can't stay under forever.

The depth of the thermocline this year is about the same as past years, however, the difference this year is that the water temperature above the thermocline is 4-5*F warmer than what I have measured in recent years.

Depth Temp (F) D.O. (mg/L)
(ft.)
0.2 88.5 6.42
3 88.7 6.4
6 88.7 6.24
9 88.9 6.31
12 88.9 6.23
15 88.9 6.37
18 88.9 6.36
21 88.9 6.31
24 88.9 6.35
-------------------------------- thermocline
27 86.4 0.14 <- start of unsatifactory DO levels
30 85.1 0.04
33 83.1 0.02
36 81.7 0.02
39 80.6 0.02
42 79.5 0.02
45 78.3 0.01
48 77.5 0.01
51 76.6 0.01
54 75.9 0.01
57 75.4 0.01
60 74.5 0.01
63 73.8 0.01
66 73.0 0.01
69 72.5 0.01
72 72.0 0.01
75 71.2 0.01
78 70.7 0.01
81 70.2 0.02
84 69.8 0.01
87 69.4 0.01
90 69.1 0.01
93 68.5 0.01
96 68.2 0.01
99 67.6 0.01
100 67.5 0.01

[occasionalfisher]

Thanks Jim for the information we appreciate all that you are doing for us.

[Mike Bucca]

Thanks for the info Jim. Wow only a difference of 2.5 degrees between above the cline and below then it starts tapering off fast. your info is just in time I just borrowed a buddies cline finder temp probe as I was curious myself of the temps versus what I am seeing on the graph. Just watch me go fishing tommorrow and catch fish at 50ft then me scratching my head all over again LOL. I haven't gotten them at 50ft lately but 3 weeks ago I was.

[Bob Smith (Porko)]

If you catch fish at 50' with any appreciable numbers then you will be going against some pretty solid biological evidence that it shouldn't be happening, Bubba!LOL! You will have a bunch of us scratching our bald or balding heads right along with ya!

I also wanted to express my gratitude to Jim Hakala! What a great asset to have on this board!!! Thanks!