Bug sampling

[Magnet]

I met a fellow named John on the Farmington today and along with his fly rod he was toting a seine that he said he made with mesh and two sticks. It had some fancy stitching on the mesh so just to tease him a little I said come on, you didn't make that. Your wife must have stitched that thing together for you. He said ,"well OK , she did make it for me but it was to my specs." He went on to talk about Gary Borger and how important the information is which we can easily and quickly can obtain from the stream using the seine. He showed me a picture of a 20 plus inch brown he caught about a half hour earlier on a fly he chose from the seine sampling he had taken earlier. His method of sampling was to hold the seine down stream and shuffle his feet thus stiring the bottom. Later iin the day, I had recalled talking about this very technique with Aaron some time ago and he posed this question to me, is the shuffle sampling actually whats in the drift? I said ofcourse it is. He said not necessarily. So I thought I would ask about this on the forum. I would like to hear Davy Wotton's thought on this. How about Silver Creek, You being a fishing buddy of Gary Borger might also have some insight on this from what Gary has told you. Also of course , any of the guys who might have a thought on this.

[AaronJasper]

If you leave the seine in the water and check it hourly that will tell you exactly what's in the drift and available to the trout during that give time period. Kick sampling will tell you what is in the stream for trout to eat, but it is nor the best indicator to show the times that the food items are in the drift.

Know what comprises the biomass of a stream is a good thing and it can only help you to have more success.

[Esopus Guy]

And I think most know that finding nymphs with darkened wing pads can alert to an appending hatch.

[rs0i]

I always carry along a small $1.00 aquarium/minnow net. I don't sample often, but if I've switched flies a couple of times and nothing is hitting, I kick up some rocks or just dunk it randomly.

This past weekend with the occasional brown stonefly hatching, I sort of had an idea of what was in the water already.

[steve z]

Shuffling your feet won't necessarily give you a good sample. You have to turn over rocks with your hands and rub them with your hands upstream from your net.

Note that if you were taking a scientific sample or sampling for density you would have to use a certain size net with certain size openings and hold the net in the water for a certain amount of time.

Even if you are just sampling to know what nymph to tie on, you should keep your sampling methods the same. Spend equal time rubbing rocks and equal time kicking bottom. Try to always hold the net in the same way for the same amount of time.

Certain species, like Hendrickson, gather in micro habitats by gender. You could kick up one of those and have a net full of Hendrickson nymphs but none of whatever else may be in the water and you might miss whatever the fish are feasting on.

If you are going to sample, one thing you should do at least once is bring like a white cooking pan and dump your sample into that so you can see how the nymphs behave. When you pull up a nymph with a net and look at it in the air it looks very different than when it is swimming around in the water. Some of them are very animated and it will change the way you think about tieing and selecting nymphs.

Also remember that nymphs like different environments and what you pull up in one place could be very different 20 feet away into a riffle or sandbar. For the most part, whatever is going week to week above the water will give you a good idea of what to tie on. Why sample the water if you know on a given day there will be Hendricksons, Blue Wings, and tan/olive caddis? You already know what nymphs are in the water. If you get a chance to look at a sample in a white pan, you will also know why the pheasant tail works so well. It looks like just about every mayfly nymph in the river.

Seining the river is kind of the absolute way or knowing. But with a little logic and bug info a hatch chart will tell you the same stuff.

[AaronJasper]

It's very inportant to know what insects live where in the stream. Tom cam vouch for that today. Knowing insect habitat will make a huge difference in catch rates under many different conditions.

Also, insect behavior and migration play a huge role in fly selection.

[Silver Creek]

Early on I used carry in my vest a sampling net for catching insects out of the air, water and stream bottom. But it was no ordinary net. It telescoped so that I could extend it underwater to the stream bottom, and I could catch insects out of the air much like a butterfly net. And if you have ever tried to catch a floating insect in your hands, you know that the hydraulic cushions forces the insect away and around your hands.

To make the net, you first must chose the pocket of your vest in which you will carry the retracted net. You don't want to make a net which is too long to fit. Then go either to an office supply store or to a Radio Shack and purchase the telescoping portion for the net. Buy one of those collapsible metal pen type pointers at the office supple store or a retractable antenna for a phone or radio at Radio Shack. You can also get an extending magnet at Harbor Tools. What you purchase will be dictated by fitting the dimensions of your vest pocket after the net is installed.

Magnetic Tool

Next purchase one of those green wire aquarium nets with the twisted wire handle. The size again dictated by your vest pocket. Make a square/rectangular net frame using coat hanger wire and transfer the net from the aquarium net to your new frame. Close the net frame by twisting the coat hanger wire together. Now comes the tricky part. You must cut off the tip of the magnet such that the hollow tube left as the tip section will hold the twisted coat hanger net. Cut the twisted wire *handle* of the net, and fit it into the hollow tip of the retractible pointer/antenna and epoxy them together.

Before epoxying them, make sure the finished net will fit into your vest pocket. If the net will not fit, bend the net wire so that it is bend back over the opening in the net. Then put the wire into the tip section of the collapsible tube so that the end of the net overlaps the tube. It will shorten the net so that it will fit into your vest.


When finished the collapsed net should look something like this:





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Now you have a telescoping sampling net that can be used to catch flying insects as well as floating ones. I find it especially useful to sample things floating below the surface film and also to sample insects living in weed beds or aquatic vegetation. Shake the vegetation with your foot and take a sample with your net. I have found scuds, aquatic worms, pupa that you would not know were present if you did the traditional turn-over-the rock-and-look ploy. Not all fish food crawls around on the stream bottom. In Wisconsin it is also useful for sifting through the muck for Hexagenia nymphs and other burrowing nymphs.

Remember to do this where you will be sampling the items on which the fish are feeding. False sampling is a common error of beginning fly fishers because correct sampling is rarely mentioned. For example if you sample where the run in which the fish are feeding, but the hatch is occurring in the riffles above the run; you won't find the correct nymph/pupa, and it likely won't be the right size. Similarly, if you sample the rocks but the fish are feeding on scuds which live in vegetation, you will get a false sample. If you sample the edge of the river but the food is originating from the middle, you might get a false sample.

Observe any fish that you see and any feeding behavior. Use that to decide what you think the fish are feeding on and where that food is originating. Then sample that food. If you don't see any fish then use your abilities in reading the water to decide where to sample. Just going to the first rock you see and turning it over may or may not be the right thing to do.

[Silver Creek]

Be wary of using a large seine like that fellow Magnet described. It Wisconsin, our DNR rangers would have cited him. It is illegal to seine for insets without a permit from the DNR.

Check the regulations in your state before using a large seine. The small net I show how to make above is pretty safe to use even in Wisconins.


Our TU chapter does teach high school students how to sample aquatic insects with the proper permits.

[AaronJasper]

Henry,

I was flipping rocks in the stream I fished today. I observed some odd things. There were stonefly nymphs in abundance on rocks that were in the slow water. I also picked quite a few free living caddis larvae off of the rocks as well. There rocks were in the center of the stream so i don't think that the stoneflies were migrating to hatch. There were multiple generations of stonefly nymphs on the rocks. Any reason in particular that they were there.

When I checked the rocks in the faster water there were more stonefly nymphs than you could count. Is it that the biomass of stoneflies was so large that some were forced out of their habitat? It was also strange to see all of those free living caddisfly larvae in the slow water as well.

[Silver Creek]

It is strange to find stoneflies in slow water. There are only two possibilities. Either they drifted/migrated there or they hatched there.

My first thought like you is drift, either behavioral or catastrophic. With catastrophic drift, the washed out insects do get deposited more often in what are the slower waters. If there has not been much rain, then more likely behavioral drift.

With drift/migration, I think we've got to assume that the stoneflies were either washed or by their own behavior drifted into the pool from above. As you know, when behavioral drift occurs, the nymphs just let go and drift with the current, and it is logical that they would slow down and tend to settle into pools, just like silt settle into pools. I can't believe they would spend energy to crawl their way upstream to a pool. So I think drift is the answer.

The other possibility is that they have been there all along. That means that in that particular pool, the habitat is suitable enough for stonefly nymphs, the flow is fast enough at the bottom and there is enough rock for them to survive and possible thrive.

Check in a couple of weeks and see if they are still there.

When sampling with the high school kids last September, I found immature hex nymphs in the faster part of the stream in sand and not mud. So I guess, nymphs are found in less than ideal places at times. I suspect this was where the eggs happened to land and the nymphs made the best home they could.