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Jim Spriggs

Data on smallmouth population

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Hi, All,

I read an interesting MDC report from 2009 that assessed the effectiveness of the smallmouth special management areas.

You can see it here  https://archive.org/details/2009StreamBlackBass

 I was especially interested in the electrofishing data. For instance, the data show that,for 1996-2007, there were 10.8 smallmouth per mile in the 12"-15" range on Ozark rivers' special management areas (Gasconade, meramec, Big, etc.).  In addition, there were 3.0 and .31 smallmouth per mile that were, respectively, greater than or equal to 15" and >=18".  

Anyone know if there are more recent data in a report somewhere? I would especially like to see the data separated by river.

 I wonder, for instance, if the smallmouth population is larger, and if there are more big smallies, today then for the time period of this report?

It would also be cool to have a graph for each Ozark river with the number of smallmouth bass per mile on the Y axis and the length of the bass on the X axis.  

The information in the report doesn't help me catch fish, but it's interesting. 

Later 

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Jim,

Let me state for the record that there is not a SINGLE smallmouth in the entire 5 mile section of Meramec that I fished today.  I can attest, quite scientifically and with peer review, that there is only 1 juvenile bluegill, and also 1 drum in our study area, encompassing Hwy N to Blue Spring Ranch.

 

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I am absolutely sure there are FAR more than 10.8 12-15 inchers per mile on all these streams.  However, assuming that the larger fish, those over 15 inches and over 18 inches, are captured by electrofishing as effectively as the 12-15 inchers are, the key statistics in table 2 in the report are the RSDs (relative stock densities).  Relative stock densities are the percentage of fish, out of all that are 7 inches or better, that are over 12 inches (RSD12), over 15 inches (RSD15), and over 18 inches (RSD18).

The table showed an RSD12 of 25.2% before special management, and 30.6% after.  RSD15 was 5.7% before, 6.9% after.  RSD18 was 0.7% before, 0.5% after.  This is what I keep harping on...the population structure.  Having more fish within the overall population being of bigger sizes.  The 15 inch minimum length limit, to that point on the streams under special management at the time, had the effect of producing more fish in the 12-15 inch range (from 8.6 to 10.8 fish per mile), more fish in the greater than 15 inch range (from 2.7 to 3.0 fish per mile), and more fish over 18 inches (from 0.25 to 0.31 fish per mile).  All that was to be expected, since theoretically, protecting fish up to 15 inches would certainly result in more fish from 12-15 inches, and with more reaching the 15 inch range, the numbers of 15-18 inchers would also increase, and those over 18 as well.  I think the biologists were a little surprised and disappointed that the numbers didn't increase more than they did, actually.  But look again at those relative stock density figures.  The percentage of fish in the population over 18 inches actually went down.  That makes sense when you think about it...increasing the numbers (and percentage) of fish over 12 inches and over 15 inches means more fish, but allowing some harvest when they reach 15 inches means they STILL don't all get to 18 inches.  So even though the numbers of 18 inch plus fish increased, the numbers of smaller fish increased MORE, and therefore made up a greater percentage of the population.

Which is why I've never been a big fan of the 15 inch minimum length.  It really doesn't do much to make a lot more fish reach 18 or 20 inches.  And...if only 0.5% of the fish that are over 7 inches are better than 18 inches, that shows the rarity and low actual numbers of these big fish, which means that killing just a few, whether legally or illegally, makes a big dent in the numbers of big fish.

The only way to make more big fish is to protect fish that are on the verge of being big ones or are already big ones.  Which is why I still would like to see slot limits instead of one fish, 15 inch limits.

But back to those fish per mile statistics for a minute.  In a typical one mile stretch of my home river, Big River, there are about 6 to 8 pools and runs that definitely hold adult smallmouth.  I would bet that on average, each pool and run holds at least a dozen over 12 inches.  Some hold far more than that, because when I was a kid and fished certain pools all summer long, and kept a lot of fish, I know I took several dozen out of those pools.  I'd bet that there are something like 100 smallmouth over 12 inches in a one-mile stretch of a productive Ozark stream. 

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Electro fishing really is not that good for sampling larger fish that hold deeper. Zaps the crap out of smaller fish and minnows that hold shallow though. Current can't really reach the deep fish. Kills a bunch of minnows and shuts fishing down for a couple days cuz the fish are full of bait. Best they have, but just a sample. Method has a ton of variables. Boat driver, fish eyes and net skills of person on the net. Stretch sampled may not be the best, but they do same, same to keep it consistent. An indicator to derive an estimate is all it is. Look at the re-sample rate to determine effectiveness if provided. Thinking 50-60% re-sample if they are good or lucky. 

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Thanks for the responses, Al and Gavin.  I'm an empiricist by training and temperament, and I enjoy learning about Ozark smallmouth and the rivers they inhabit. 

Of course, I like being on the water and fishing for smallies even more than reading about them.

 

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I have been on a shocking survey before, big fish are VERY uncommon.... food is not the issue for growing larger smallmouths, it takes a very long time to grow a big smallmouth IF and I mean IF..the individual has the Genetics to get large..some of those 12 incher may be 5-6 years old while a 18" may be younger....fish over the years get "fished down"

I would like the state to realize that, perhaps capture some big fish, or select the fastest growing  biggest fish from a brood and work on getting sizes up...(selective stocking)

Large smallmouths should be returned, the genetics are important, I know guys who gig suckers in the winter, I know guys who have whoopsed big smallmouth, they felt horrible for it ...but it does happen....spotted bass should have no limit in "blue ribbon" Ozark smallie streams....I have fished many many a mile of Ozark streams....

for huge smallmouths, more have come from shoal creek and spring river....trick is finding they right Habitat for old brown bass...that and both those waters don't get the pressure on bass like others...

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19 hours ago, MoCarp said:

I have been on a shocking survey before, big fish are VERY uncommon.... food is not the issue for growing larger smallmouths, it takes a very long time to grow a big smallmouth IF and I mean IF..the individual has the Genetics to get large..some of those 12 incher may be 5-6 years old while a 18" may be younger....fish over the years get "fished down"

I would like the state to realize that, perhaps capture some big fish, or select the fastest growing  biggest fish from a brood and work on getting sizes up...(selective stocking)

Large smallmouths should be returned, the genetics are important, I know guys who gig suckers in the winter, I know guys who have whoopsed big smallmouth, they felt horrible for it ...but it does happen....spotted bass should have no limit in "blue ribbon" Ozark smallie streams....I have fished many many a mile of Ozark streams....

for huge smallmouths, more have come from shoal creek and spring river....trick is finding they right Habitat for old brown bass...that and both those waters don't get the pressure on bass like others...

Good stuff 

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On 6/5/2017 at 9:21 PM, Al Agnew said:

I am absolutely sure there are FAR more than 10.8 12-15 inchers per mile on all these streams.  However, assuming that the larger fish, those over 15 inches and over 18 inches, are captured by electrofishing as effectively as the 12-15 inchers are, the key statistics in table 2 in the report are the RSDs (relative stock densities).  Relative stock densities are the percentage of fish, out of all that are 7 inches or better, that are over 12 inches (RSD12), over 15 inches (RSD15), and over 18 inches (RSD18).

The table showed an RSD12 of 25.2% before special management, and 30.6% after.  RSD15 was 5.7% before, 6.9% after.  RSD18 was 0.7% before, 0.5% after.  This is what I keep harping on...the population structure.  Having more fish within the overall population being of bigger sizes.  The 15 inch minimum length limit, to that point on the streams under special management at the time, had the effect of producing more fish in the 12-15 inch range (from 8.6 to 10.8 fish per mile), more fish in the greater than 15 inch range (from 2.7 to 3.0 fish per mile), and more fish over 18 inches (from 0.25 to 0.31 fish per mile).  All that was to be expected, since theoretically, protecting fish up to 15 inches would certainly result in more fish from 12-15 inches, and with more reaching the 15 inch range, the numbers of 15-18 inchers would also increase, and those over 18 as well.  I think the biologists were a little surprised and disappointed that the numbers didn't increase more than they did, actually.  But look again at those relative stock density figures.  The percentage of fish in the population over 18 inches actually went down.  That makes sense when you think about it...increasing the numbers (and percentage) of fish over 12 inches and over 15 inches means more fish, but allowing some harvest when they reach 15 inches means they STILL don't all get to 18 inches.  So even though the numbers of 18 inch plus fish increased, the numbers of smaller fish increased MORE, and therefore made up a greater percentage of the population.

Which is why I've never been a big fan of the 15 inch minimum length.  It really doesn't do much to make a lot more fish reach 18 or 20 inches.  And...if only 0.5% of the fish that are over 7 inches are better than 18 inches, that shows the rarity and low actual numbers of these big fish, which means that killing just a few, whether legally or illegally, makes a big dent in the numbers of big fish.

The only way to make more big fish is to protect fish that are on the verge of being big ones or are already big ones.  Which is why I still would like to see slot limits instead of one fish, 15 inch limits.

But back to those fish per mile statistics for a minute.  In a typical one mile stretch of my home river, Big River, there are about 6 to 8 pools and runs that definitely hold adult smallmouth.  I would bet that on average, each pool and run holds at least a dozen over 12 inches.  Some hold far more than that, because when I was a kid and fished certain pools all summer long, and kept a lot of fish, I know I took several dozen out of those pools.  I'd bet that there are something like 100 smallmouth over 12 inches in a one-mile stretch of a productive Ozark stream. 

Electro sampling is not the tell all. At best it gives a very dim light, so to speak, into a lightless room. But it does give highly valuable information, especially when done over a period of years. 

The effectivness of this type sampling is very limited in scope but does give insight to the whole. The electro field is small and usually gets 10% or less of the fish in any given area. And at that, large fish are able to escape the field. And the effectiveness can even be affected by those doing the sampling. Some samplers are better at it than others. 

You state that you bet there are 100 12 inch Smallmouth in a 1 mile stretch. I'll tell you there are 3-4 times that amount. It's a shock and amazement to learn what all a stream supports! 

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22 hours ago, MoCarp said:

   I have fished many many a mile of Ozark streams....

for huge smallmouths, more have come from shoal creek and spring river....trick is finding they right Habitat for old brown bass...that and both those waters don't get the pressure on bass like others...

You may want to sign up on some more social media sites. 

They are both getting pounded. In fact stretches of every creek in this area is getting a ton more pressure than I ever thought! I was shocked at what all I was reading. At least I'm seeing a trend to C&R. But I'm seeing stringers too.

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Spring river doesn't get floated as much as other ozark streams prob because of all the brush piles.....shoal creek has some fishing pressure in spots, but nothing on the level as some of the others...could that change? sure....then there is the secret trout fishing upper spring river holds...shush..don't tell anyone ;) 

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