Anatomy of a Trout Stream November 26, 2021 – Posted in: Films – Tags: , , , ,

From 1985, this video features Rick Hafle, an environmental scientist with a masters degree in entomology, and all-around fly-fishing pro.  Hafle was also the co-author of the book, Western Hatches.  When viewed as part of the entire SA Mastery series videos that focus on fly fishing for trout, Anatomy of a Trout Stream is a great fit and addresses a number of items not covered in the Borger or Swisher videos.

This video focuses more on the fish themselves, how they feed in relation to the various parts of a river or stream.  We learn that trout need 4 things to survive- food, protection from current, protection from predators, and comfort in water temperature and oxygen.  In order to survive, trout (and all fish) need to take in more energy from food than they use while chasing food.  Because of this trout will position themselves in locations where the maximum of food can be brought to them with a minimal amount of energy being lost.  

Trout often feed in “little bites” such as aquatic insects, terrestrial insects, and crustaceans that are found in abundance and require little energy expenditure.  If chasing “large bites” such as crayfish, minnows, leeches, and other larger prey- the energy gained has to exceed the energy used in the pursuit of the prey.  This is a true concept for all living things.  

Hafle breaks a river into 4 main parts- riffles, runs, pools, and flats.  The angler needs to learn to read the water in all of these places and how to locate “prime lies”.  These are the places that offer trout comfort, protection, and a food.  Depending on the situation, the fish may move to different locations to position themselves in a prime lie.

Riffles are mainly feeding locations as they are prime food production areas.  They are the best place to start if you are fishing new or unfamiliar water.  Holding lies are easily located and the turbulence of the water allows the angler to approach close for easy casting.   Use a seine and imitate the most abundant insect for success.

Hafle’s description is similar Gary Borger’s of fishing riffles.  He adds on to both Borger and Swisher by giving a detailed description of the caddis life cycle, the various imitations used, along with when and how to use them.  Hafle also mentions “biologic drift” and increased insect activity both early and late in the day.  

There were several things brought that are rarely mentioned in regards to fishing caddis imitations.  One is that the pupal stage is very short, but is an important stage to be aware of.   The angler needs to be able to identify when trout are feeding on the pupa.

Another is the fact that the adults of some caddis species dive to lay their eggs and this can be imitated by letting an adult imitation swing and get pulled under by the current.  The caddis dry can be dead-drifted, made to dive, or to skate and skitter depending on the species and situation.   

Hafle describes runs as being extensions of riffles.  They are generally deeper than riffles and harder to wade and fish.  He does show the use of sink-tip and sinking lines to fish stonefly nymphs here which is a technique we should all probably learn.  Today, we know that an indicator rig as we fish them today could be used successfully in this application.  Hafle does demonstrate a rudimentary indicator rig for fishing riffles, but does not carry this over to fishing runs.

Areas where riffles transition to runs are a key location.  Insects hatching in riffles will be present and both surface and sub-surface opportunities will be available.  Again, try to identify the most abundant insect to make your fly selection.  Pay attention to deeper areas close to the bank where trout will hold to feed.  Terrestrial insects can be important here on warm, windy days.  These areas can also be fished with streamers.  

Hafle states that pools are hard to fish effectively due to their depth and scattered holding areas.  They often hold the largest trout, but getting a fly to them is a challenge.  The fish either need to be drawn into reachable areas by food (hatching insects) or we can try to take a fly to them.

There are three parts of a pool- the head, the body, and the tailout.  Each part is fished differently.  Depending on its configuration, the head is usually fished like a riffle or run.  Pay attention to the most abundant insect and focus on it.  Again, surface or sub-surface imitations can be used depending on what the angler observes.

The body is often fished best with a streamer on a sink-tip or sinking line.  This allows water to be covered quickly and the streamer can pull trout from holding areas for a “big bite”.   There three variables in streamer fishing to focus on in pools.  The fly itself, the depth it is fished, and the speed of the retrieve.  These things vary and the angler should look for any noticeable consistencies on a given day.

The tailout is a dry fly area and dry fly rules apply.  If there are no fishing rising, it is probably best to bypass this and fish elsewhere.  If fish are rising, try to identify the insect and stage.  Select your fly based on observation.  Carry a small aquarium net to help catch and identify insects.

Flats are broad stretches of water that are usually fairly shallow.  Once again try to find feeding fish and identify what they are eating.  Careful observation is needed as there may be multiple insects on the water.  Wade carefully to avoid any disturbance on the water.  The dry fly is fished down and across allowing the fly to dead drift over the feeding fish.  Let the fly drift out of the trout’s window before picking it up to recast.  We have seen this technique before in Doug Swisher’s videos. 

Fly styles and selection are quite rudimentary in the video, but this was not it’s primary focus.  These things are covered extensively in other videos of the Mastery series.  The section on caddis alone is makes this video worth watching.  This information should add to any trout angler’s success.

Anatomy of a Trout Stream is a great review for anyone who fly fishes for trout.  The beginner will receive and wealth of information about locating trout in moving water and how they feed along with some basic entomology.  The experienced angler will get a number of reminders and possible learn a new thing or two.  When put in combination with the Other Mastery trout videos, they give a complete, comprehensive look at fly fishing for trout in rivers and streams.

Scientific Anglers has partnered with the American Museum of Fly Fishing in the effort to digitize these classic film masters for future generations.