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Catt

Surface temperature?

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It is widely preached that water temperature affects the spawn and that is 100% correct but what most everyone forgets is when we read the temperature on our electronics we are reading surface temperature. The temperature that affects bass is at 1'-8'+ below the surface, so when we read 65 degrees on the surface the temperature at 1'-8'+ below the surface is drastically colder.

This spring on Toledo Bend I've found surface temperatures on the south end in the upper 50s since mid-February and last week I was reading temperatures in the upper 60s to lower 70s and yet the bass were not on the beds at least not in large numbers.

The Pine trees are pollinating, the Dogwoods are in bloom, bass are in 2-8' of water, the full moon of March has passed all the normal signs of spawn but yet the bass are saying it aint time.

What bass do now is what bass did thenif you think they won't believe me they will ;)

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I'm still "old school" when it comes to getting water temperature. I have a stream fly fishing thermometer, that I drop to the bottom and get the temperature at the bottom. Much more accurate.

Falcon

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I've been trying to get a handle on the spawn for the past few years, and getting more earnest each year; The last two years I've only observed and not fished the spawn. This will be year three. I've also been collecting scientific and angling literature on the subject. The original intent was to determine if moon influence was real, and how it influenced the spawn. It's expanded into behavior too -an obvious extension.

I've purposely observed ponds of different volume and the smallest/shallowest begin and end spawning earliest, and temperature appears to be the main factor. The difference between my shallowest waters and deepest has been about 2 weeks, but more than a month compared with local larger reservoirs.

Some of my very shallowest ponds are all of four feet deep and have reached 60-70F almost two months early, but the bass do not spawn. There are a number of reasons for this; things that must come together to trigger the spawn.

-First, there is almost certainly an endogenous (internal) rhythm involved, probably set the previous year.

-Final egg development takes some additional time, and body condition of females coming out of winter can affect timing.

-Researchers talk of "temperature stability", that is, temps need to reach a certain level and stay there for a time. The literature all points to ~60F for LM. I am not sure how to get at this myself with the time and equipment at my disposal, but it seems as though reaching the very upper 50s at three to four feet in depth is enough of a "heat sink" to turn the light green. Now, realize this is in shallow ponds that do not have a large volume of cold water that might inundate a spawn site with cold water on the next big blow. This, I believe, is why protected coves in larger waters are such popular spawning locations and tend to spawn first. They are like ponds within a lake. So, topography matters.

My shallow ponds are at risk of chilling from cold snaps and it does happen, likely killing the eggs. I measured 48F in some nests last year -yet a couple males stayed on the job. And this pond has poor hatches every year (but good growth in the survivors). Maybe they'll get lucky some year -I've seen this boom and bust scenario, and look forward to it ;). More voluminous waters buffer the affects of fronts, and since they spawn later the fronts are usually less intense.

-Lastly, the moon appears to have a strong influence. Hopefully this year I can wrap up the moon observations, and put some real numbers to it.

There are other things too, but these are key on my ponds.

Oh yes, you are very correct: Measuring heating is more complex than most anglers realize. Surface temps, by themselves, can mean very little. However, if you understand how heating works, such a ballpark number can give you a sense of what's going on.

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Nice thread, Catt, and great information to prod our thinking, Paul.

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Surface temperatures can be completely misleading; last week I read surface temperatures in the mid 60s in open water over depths of 15' and lower 70s in protected areas of 4-8'. But when I drop a probe down 2-3' in those areas I find it reads 15-25 degrees difference which is a completely different scenario as far as what the bass are doing. Now the bass that were on beds in either area were small immature bass and the mature bass were feeding actively in a per-spawn mode.

I find the more I think I have the bass figured out the more the bass prove to me I don't ;)

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Surface temperatures can be completely misleading; last week I read surface temperatures in the mid 60s in open water over depths of 15' and lower 70s in protected areas of 4-8'. But when I drop a probe down 2-3' in those areas I find it reads 15-25 degrees difference which is a completely different scenario as far as what the bass are doing. Now the bass that were on beds in either area were small immature bass and the mature bass were feeding actively in a per-spawn mode.

I find the more I think I have the bass figured out the more the bass prove to me I don't ;)

Thanks for the info Catt. I was going to ask how drastic of a difference you've seen. Great information too Paul!

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Surface temperatures can be completely misleading; last week I read surface temperatures in the mid 60s in open water over depths of 15' and lower 70s in protected areas of 4-8'. But when I drop a probe down 2-3' in those areas I find it reads 15-25 degrees difference which is a completely different scenario as far as what the bass are doing. Now the bass that were on beds in either area were small immature bass and the mature bass were feeding actively in a per-spawn mode.

I find the more I think I have the bass figured out the more the bass prove to me I don't ;)

Wow!  That is a huge difference in temperature.  I would bet that a temperature differential like that will occur only in the Spring when the first few inches of water receive heat while the depths are still very cold from the Winter.  In the Fall, when the surface cools enough to result in turnover and the water mixes, I don't see this happening.  I would be really curious to see what happens in the summer when the water temps reach the 80s and even the 90s on the surface.  Does anyone have any readings from this time period?

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I would bet that a temperature differential like that will occur only in the Spring when the first few inches of water receive heat while the depths are still very cold from the Winter. In the Fall, when the surface cools enough to result in turnover and the water mixes, I don't see this happening. I would be really curious to see what happens in the summer when the water temps reach the 80s and even the 90s on the surface. Does anyone have any readings from this time period?

Right on! Surface temp is skin deep, at least when there's a mass of cold below it.

I have summer profiles and find heat penetrates pretty well. The reason is that water is stingy in both taking on and releasing heat. That's why I call it a cold sink, or heat sink. That's what it is. In summer, once it warms, the short warm nights can't rob enough heat.

My summer profiles are only as deep as my ponds -8 to 18feet. I see only about a 3-8degree drop from surface to bottom. In deeper lakes, thermoclines tend to set up at around 15 to 20 feet in early summer, and get progressively deeper as the season wears on.

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