All good trout rivers are full of rocks. Bankside and midstream, big ones and small ones — rocks are everywhere. Unless the bottom is gravel or sand for long stretches, the composition of the riverbed is a series of boulders and stones scattered in various sizes. Trout thrive in these places because rocks create structure and current seams. That structure offers protection, while the seams provide feeding lanes. And to the fisherman, those lanes are everything.
Downstream of every rock are three obvious seams: the left seam, right seam and the slower seam in the middle. That part is easy. But the most productive seams are more hidden, and many anglers seem to miss them altogether. These are the two merger seams, where each fast seam meets the slower part in the middle. And if I had to pick just one target area, day after day and season after season, I would surely choose the merger seams.
Merging
Anywhere faster water meets slower water is a merger point. The old adage that foam is home applies here, as merger seams certainly are the collecting point for those bubble lines. But only a small percentage of merger seams form bubbles, and the attentive angler finds merger seams behind literally every rock.
The merger seams behind every rock are easy to find. Look for the three main seams: fast left, fast right and slow center. Now find where the slow water meets the fast water, and treat those two strips of water as their own seams. These are the mergers.
Most often, merger seams are narrow strips, from just a few inches wide to twelve inches or better. Sometimes these lanes are ten or twenty feet in length and easy to follow, and other times the merger is very short — just a foot or two — before it blends in with the neighboring seam or is overtaken by the next lane. But the mergers are there, and trout know it. Fish sit with their bellies on the bottom of these seams, because they have the best of everything — softer water to sit in, and food drifting by. Often, that food is concentrated in a skinny seam and drifting directly to the waiting trout.
READ: Troutbitten | At the Front Door of Every Rock
My friend, Greg.
Precision Targeting
Anglers of all types quickly understand that accuracy is imperative if any consistent success is to follow. So most beginners develop the necessary skills to place the fly in an area. But the next-level angler continues to refine that accuracy until true precision is achieved. The first goal is to fish all three main seams that are downstream of a rock (left, right and center). And a step beyond that is to target the merger seams. That’s hard, because the fly and tippet must cooperate enough to hold a narrow strip of water without drifting into the neighboring seam, fast or slow (assuming the goal is a dead drift).
Such skill comes with time and persistence. But the payoff can be extraordinary. Suddenly, a pocket that produced nothing with an area-approach can turn up a handful of fish with a tediously targeted multi-seam approach — especially when focusing on the mergers.
Pocket Water Advantage
An abundance of rocks combined with a high gradient creates a fisherman’s favorite — pocket water. And whether I’m fishing dry flies, nymphs or streamers, I’ll choose the broken pocket water every time I’m given the chance.
With endless seams and oxygenated water, boulder strewn runs are the food factories of a river. Add in the extra cover and the fact that many anglers avoid the challenge of such places, and pocket water is the perfect chance to catch a pile of trout.
Mixed into every stretch of pocket water are countless lanes that mix and blend with each other. And downstream of every rock are five seams — not just three. Fish the mergers. Find the trout.
Fish hard, friends.
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Enjoy the day.
Domenick Swentosky
T R O U T B I T T E N
domenick@troutbitten.com
Dom, Another great arrival. I’m trying to picture seams4-5.are they inside of 3-4 or below.Thanks to your great tutoringI’ve become a much better nympher and improving on my dry fly presentation.Thank you. Pete
Hi Pete,
They are inside of the main, fast seams. Reread the “Merger” section above. It’s there.
With this in mind, you’ll find them.
Cheers.
Dom
Thanks Dom,It was there as you said thanks . Pete
Not quite sure what you mean by seams 4 and 5. Are they just the inside of the 2 fast streams along the middle slow seam or are they downstream further somewhere? Maybe an arrow or 2 to point out 4 and 5?
Hi Matt,
Please look at the text above in the “Merger” section. The description is solid. Especially the second paragraph:
“The merger seams behind every rock are easy to find. Look for the three main seams: fast left, fast right and slow center. Now find where the slow water meets the fast water, and treat those two strips of water as their own seams. These are the mergers.”
Cheers.
Dom
Thank you Dom
This seams significant but without a picture not much to get from it. can you provide a picture or a reference to one?
Thanks George
Sorry, no picture today. But if you read the description in the “Merger” section above, and then look at the cover shot, you’ll see them.
Hope that helps.
Dom
I have the same question as Pete. I try to fish all three seems as far down from the rock as possible including the cushion in front of the rock. I have found that fish will hold surprisingly far back behind the rock. Thanks!
Have hooked huge trout way farther back behind the boulder then would of expected,also. Never knew about other spots,actually mainly focused on the eddie behind rock. Like I tell all beginners that want to focus on gear and casting,nothing matters if you can’t find fish,and on the bigger water becomes even harder. Let’s go find 5 seams,today!!
There ya go, Rich!
Cheers.
Dom
I agree, Karrick. the merger seams basically keep going and widening until something eventually breaks them up or they finally fizzle out.
This from above:
“The merger seams behind every rock are easy to find. Look for the three main seams: fast left, fast right and slow center. Now find where the slow water meets the fast water, and treat those two strips of water as their own seams. These are the mergers.
Most often, merger seams are narrow strips, from just a few inches wide to twelve inches or better. Sometimes these lanes are ten or twenty feet in length and easy to follow, and other times the merger is very short — just a foot or two — before it blends in with the neighboring seam or is overtaken by the next lane.”
Cheers.
Dom
thank you so much for your incredible insights and awesome writing style.
I’m a bit late to the party here, but you’re missing additional seams that boulders also create: the pocket down and under the front, and the low pressure zones going back up along the sides right on the bottom.
This front pocket eddy (which I read somewhere is called the horseshoe eddy or upstream cushion), is created when the water hits the front of the boulder, pushing the current down and back upriver. The eddy takes river bottom material with it, eventually creating a pocket with a drop off at the leading edge.
Adding to that, on the leeward side of the boulder that low pressure zone there also pushes water back up along the sides, digging material out and extending that front pocket.
Leading a nymph down that front drop off is killer, and the sides can produce well if you can read those seams right and get the right depth. I suck at these two because the higher pressure speeds the water up throughout most of the higher columns.
To make this work you have to cast upstream a decent distance to get to the depth needed. Of note, the water is often calmer up front, so stealth can be troublesome. Finding the right approach is critical.
Swinging a streamer just upstream, or over the top of the pocket, can be productive and pretty explosive.
Since I’ve never noticed a fish come up out of that pocket for a dry/emerger I don’t bother with them. I assume they swim upriver a bit for top-water feeding, where they can see further up stream for approaching bugs.
I think that this front pocket is the prime spot for the fish since they get first looks, and I usually catch larger fish there than I catch downstream of the boulder.
So I’d put the total seams at 8.
Good stuff. Love that description. I also have an article about that front side of the rock.
ARTICLE: Troutbitten | At the Front Door of Every Rock
I’ll say this: You’re talking more about pockets and not lanes/seams. You’re also talking about water depth. Of course all of that matters greatly, but for THIS concept, it’s just about the lanes/seams created.
Cheers.
Dom