Reading Water — Every Rock Creates Five Seams

by | Apr 8, 2021 | 13 comments

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

 

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Domenick Swentosky

Central Pennsylvania

Hi. I’m a father of two young boys, a husband, author, fly fishing guide and a musician. I fish for wild brown trout in the cool limestone waters of Central Pennsylvania year round. This is my home, and I love it. Friends. Family. And the river.

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13 Comments

  1. 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

    Reply
    • 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

      Reply
      • Thanks Dom,It was there as you said thanks . Pete

        Reply
  2. 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?

    Reply
    • 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

      Reply
      • Thank you Dom

        Reply
  3. 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

    Reply
    • 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

      Reply
  4. 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!

    Reply
    • 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!!

      Reply
    • 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

      Reply
  5. thank you so much for your incredible insights and awesome writing style.

    Reply

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Domenick Swentosky

Central Pennsylvania

Hi. I’m a father of two young boys, a husband, author, fly fishing guide and a musician. I fish for wild brown trout in the cool limestone waters of Central Pennsylvania year round. This is my home, and I love it. Friends. Family. And the river.

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