Your bug seine is your eyesight into what is going on under the water.  Most people think matching the hatch is all about figuring out what goes on above the surface, but it is just as important to match what is going on below the surface when selecting the right flies for nymphing.

It isn’t too hard to get hit in the face with a salmonfly and see then along the banks to know that the salmonflies are hatching and active on the river, but how would you know that white midge larva are getting dislodged from the rocks upstream and the trout in that same hole could care less about those salmonflies and they are gorging themselves on the midges?

The ONLY way you’re going to figure that out is by seining the river below that hole and finding them in your seine or by kicking rocks and hoping to find those bugs.

Why a Bug Seine instead of Just Kicking Over Rocks

A reader of ours asked this question recently and it’s a great question as most people don’t use a seine. I believe a seine is one the essential tools all anglers should have on the water for many reasons and is vastly superior to flipping over rocks.

First, you can only see what is under and around rocks when picking them up. When you do this many insects will let loose of the rocks and drift away from you before you even spot them, blurring your results from what you discover.  Baetis mayflies and other strong swimming nymphs hardly ever stay on the rocks and stonefly nymphs will also drop off when a rock is disturbed.

Second, a bug seine allows you to seine the flows of the river, not just what is under rocks. This means you can see what is dead drifting in the river right below where you will be fishing. This is something we talk about in our entomology course, but there is a menu method and dinner plate method to seining for bugs. The menu method is similar to kicking over rocks and seeing what is in the river (aka on the menu), but that doesn’t mean a trout is going to eat it just because it’s on the menu. The dinner plate method shows what is actively working and drifting in the river, where trout will predate on insects. Trout rarely kick over rocks and scavenge on the bottom, they wait for insects to move around or get dislodged before they eat them. Whatever is floating through the substrate is very likely on the menu. This single difference is likely the most important because you can see a red midge on a rock and throw it all day with no success but if you see a white midge in your net, or even 50 in your net, you will have much more success tying that on and trying it in the water upstream of where you seined.

Third, You can collect more insects, more easily.  During winter, getting your hands too wet is not fun, and there are only so many insects you can hold in your hands as your flipping rocks.  In addition, you can filter the top of the water column and collect freshly emerging or newly emerged insects from the surface helping you see what is hatching, something rock flipping can not help with in the slightest.

Far to often we find a hatch above the water, but don’t see fish rising.  That usually means that the fish are more concerned with the bug life below the water.  Fish feed subsurface 90% of the time because it’s less energy used and it’s safer.  The way to catching more fish is by understanding what happens below the water and the only way to do that is with a seine.

What about flipping rocks over? I know a lot of you think flipping rocks is the same as seining, but there is one major difference.  Flipping rocks shows you what is in the river, seining shows you what’s moving through the river.  Fish aren’t flipping over rocks and eating insects, they are eating what goes through the water.  A seine shows you what is on the menu so you can use the right flies as you nymph that run or hole or riffle.

With all that said, the best way to use your bug seine is if possible, seine above and below where you plan to fish.  Seine above the hole and see what’s moving around (kick up rocks at this point to see whats above the fish) then work below the fish and see what is just drifting through the water (not kicking up rocks, just collect what’s in the current.)  This is huge to your success in identifying what the trout are eating.

If you can find similarities in what happens above the fishable water and below the fishable water, you’ve likely narrowed down your choices of flies to 5-6 patterns at the most.  That will help you a ton in selecting the right fly when you are nymphing.

Check out our entomology course, the course comes included with a free bug seine AND three 50% off coupons to use in our shop, so you can get the fly assortments at insane prices.

If you believe that this will help you and using a seine and having the right flies ahead of time is key to catching the right fish, then our course is a perfect way to save money.  You can buy the course for $199 and then get an assortment for less that $90 meaning for less than $300, you can have all the flies and knowledge you need to catch flies all year long.  That is a great value, and well worth the investment.  Knowledge carries on forever, so make an investment in your fly fishing career and check out our course today.

Ok enough of that, I don’t like to be too pushy when I promote the course, but it has been so helpful to so many people, I have to bring it up where relevant.

Some of our readers have had other questions around using the bug seine that I’m going to answer here now as well.

You mention seining above and below holes you plan on fishing, won’t this disturb the fish?

Short answer is no, but you have to do it right and give enough room. Not all places are going to allow you to seine above and below a hole without spooking the fish. This is especially true on small creeks or places where the only way to get above the hole is to wade in the water or even through the hole. If you can, however, seine below and above a hole as you often can on larger rivers that you are wading (rivers that are probably 30+ ft wide) you often get long riffles above the holes, allowing you to get well above the hole and not spook the fish. That is the best spot to kick up rocks and collect the bugs in your seine, because that is the food that is going right into the hole you’re going to fish. The debris you kick up doesn’t spook the fish, and likely gets them jazzed up. People call it the san juan shuffle, where shuffling your feet on the river bottom can send a bunch of insects down river and get the fish actively feeding. Though I don’t encourage this often, it is a common bi-product of seining above the river.

Best answer to this is to simply make sure you prioritize not spooking fish to seining the hole completely. Seine what you can if you have not yet figured out the patterns that are working for the day and then work from there.

How many times a day do you seine?

Short answer is as many times as is needed to start catching fish consistently in every hole I fish. While it can change from hole to hole, there is often a pattern on the river because insects respond to environmental signals (weather, temps, water temps, etc) and those don’t change too much over 3-5 miles of water, which is about as much as anyone would cover wading or floating in a day. Once you’ve seined and found 2-3 good guesses for what to throw and it works and puts fish to net in 2-3 spots you fish, you’ve usually found a pattern that will work most of the day unless the environment changes. If you don’t get success with your first seine, repeat again. I often fish the first hole I find that I know has fish in it for an abnormally long time, switching up flies until I feel that my fly selection has been sufficient enough to catch fish. This is just an experience thing and different for everyone, but I like to isolate the variables and fish the same hole from the same spot, changing my flies until I get success or feel like location or presentation are the problems more than fly selection. If you just move to the next hole and catch a fish, that changes the location and while fish were caught, it may not be a true “pattern” on catching fish. The goal is to always find success you can repeat aka a pattern. Use your bug seine as many times as is needed to find that pattern and then you can put the seine away and rake in the fish.