Trout Numbers Vs. Cubic Feet Per Second

[ozark trout fisher]

I was doing a little number crunching a while back, comparing trout per mile numbers with different streams. I realized, that considering how much the size of trout streams in Missouri vary, it's a relatively useless number. So I thought it would be interesting to compare trout streams based on their trout per mile numbers, divided by their mean flow. Now I realize right of the bat there are a few problems with this. Mainly, stream flow varies greatly throughout the year. Still, I thought it might be interesting for some. Also, I should point out that shocking data is missing from some years. Also, I only got this data for a few streams (the ones I could most easily obtain fish shocking data for). I appreciate the Missouri department of Conservation providing that data.

Mean Flow Rates of Four Missouri Streams 2001-2007

(Cubic Feet per Second-CFS)

Current River above Akers, MO

MEAN 328.1

Meramec River near Steelville, MO

MEAN 506.5

Eleven Point River near Bardley, MO

MEAN 729.5

Little Piney Creek at Newburg, MO

MEAN 155.9

Mean Trout per Mile Numbers 2001-2008

Current River 467 Trout per mile

Meramec 356 Trout Per mile

Eleven Point River 752 Trout per mile

Little Piney Creek 157 Trout Per Mile

Number of trout in each cubic feet per second of stream (if you follow what I mean by that)

Current River 1.42 Trout per CFS

Meramec River 0.7 Trout per CFS

Eleven Point River 1.03 Trout per CFS

Little Piney Creek 1.01 Trout per CFS

So just kinda take this for what it's worth, which I'm sure ain't much...

[Brian K. Shaffer]

my opinion -- Taneycomo = 5000 + trout per river mile

no research here... just a hunch :-)

Brian

[ozark trout fisher]

my opinion -- Taneycomo = 5000 + trout per river mile

no research here... just a hunch :-)

Brian

Probably. I just couldn't find the data I needed for Taney.... They survey that in fish per acre, which really doesn't fit this sort of thing.

[Brian K. Shaffer]

I remember reading once.. years ago;

Rainbow trout like water that flows at them at 1ft per second

Brown trout like water that flows at them at 3-4 inches per second

Always been proven true in my fishing.

Brian

[brownieman]

OTF,

All this depends on the accuracy and reliability of the MDC results.

The bioligists doing the shocking compile their own data, draw their own results and put whatever they please on paper and no-one questions it.

I know often times the bioligists that are in charge of certain bodies of water live no where near it and spend little actual time on it...but they are the experts...what the heck do I know, I just walk up and down the river a lot

Guess it depends on how much faith you have in the 'Powers That Be'...ya know.

later on

[eric1978]

You also have to consider that CFS flows don't necessarily determine volume of water in the stream. Wider and deeper streams and reservoirs will always hold more water, regardless of flow (regular flow, not talking about periods of flooding). Taney will always have more volume than, say, the Meramec, simply because it's dammed and wider. Larger bodies of water means more available space for more fish per mile. I'm not sure the flow has any direct correlation to population, except that some flows are more ideal for certain species than others. What would be a more relevant statistic is fish per square mile, but that would be a logistical nightmare for MDC to calculate.

[ozark trout fisher]

You also have to consider that CFS flows don't necessarily determine volume of water in the stream. Wider and deeper streams and reservoirs will always hold more water, regardless of flow (regular flow, not talking about periods of flooding). Taney will always have more volume than, say, the Meramec, simply because it's dammed and wider. Larger bodies of water means more available space for more fish per mile. I'm not sure the flow has any direct correlation to population, except that some flows are more ideal for certain species than others. What would be a more relevant statistic is fish per square mile, but that would be a logistical nightmare for MDC to calculate.

Yeah, when I decided to come up with these numbers, I knew these sort of problems were inherent to it. I just hadn't ever seen it done before, and I thought I may as well see what I found. I think it's at least a bit interesting, if not terribly useful.

Although I realize CFS is a pretty poor indicator of stream volume, I don't know of a better measure. So you just kinda have to work with what you got, you know what I mean.

[Al Agnew]

You could quickly fry your brain cells thinking about stuff like this...

Mean flow probably isn't the best indicator even of the flow. Trout and other fish habitat is limited by the low water periods. So average low flows are probably a better indicator than mean flow. Mean flow is skewed by the very high flows of major floods. A river with a big watershed, like the Niangua, for instance, is going to have a greater percentage difference between mean flow and average low flow, compared to the upper Current, which has a very small watershed upstream and so almost never floods huge volumes of water. In other words, not as much difference between low flows and floods on the Current as on the Niangua, or almost any other stream in MO that you could name. The Meramec has a HUGE difference between low flows and floods, because it has a very large watershed both on the upper Meramec and the Dry Fork to furnish great volumes of flood water.

I like Eric's take on it, too. Although cfs DOES measure the volume of water flowing through the river, it does not measure the volume of space the fish have to live in. When it comes to trout habitat, a large river that has a fairly low gradient, like the Niangua, will probably have less trout habitat per mile than a a river of similar size (like the Eleven Point) that flows faster. On the other hand, the Niangua has more AREA of trout habitat than a smaller stream with just as much water with good current.

See what I mean about frying your brain cells?

[ozark trout fisher]

You could quickly fry your brain cells thinking about stuff like this...

Mean flow probably isn't the best indicator even of the flow. Trout and other fish habitat is limited by the low water periods. So average low flows are probably a better indicator than mean flow. Mean flow is skewed by the very high flows of major floods. A river with a big watershed, like the Niangua, for instance, is going to have a greater percentage difference between mean flow and average low flow, compared to the upper Current, which has a very small watershed upstream and so almost never floods huge volumes of water. In other words, not as much difference between low flows and floods on the Current as on the Niangua, or almost any other stream in MO that you could name. The Meramec has a HUGE difference between low flows and floods, because it has a very large watershed both on the upper Meramec and the Dry Fork to furnish great volumes of flood water.

I like Eric's take on it, too. Although cfs DOES measure the volume of water flowing through the river, it does not measure the volume of space the fish have to live in. When it comes to trout habitat, a large river that has a fairly low gradient, like the Niangua, will probably have less trout habitat per mile than a a river of similar size (like the Eleven Point) that flows faster. On the other hand, the Niangua has more AREA of trout habitat than a smaller stream with just as much water with good current.

See what I mean about frying your brain cells?

Like I said, I don't have any much better way to assess the volume of water than the mean Cubic Feet per second . I just kinda thought it was interesting.... Not meant to be anything definitive. In the original post I said there were a lot of reason this data isn't perfect. I just thought it was worth posting.

My bad....

[Kayser]

If I could get the mean current speed for the CFS values (would like from low water periods), I could do a quick calculation of how many cubic feet of living space are needed per trout at low water periods. Divide the CFS by the speed to get the cubic feet per mile (be sure to convert hours to seconds), then divide the CF/mi by the trout per mile, and get CF/trout. Could be an indicator of overall trout productivity of the stream, and thus quality of habitat. Then again, getting the mean speed would be a royal pain...

Rob