By: Jacob Noteboom
Many of us have seen fish eat insects from the surface of the
water. That may be what first drew our attention toward fly fishing. But oftentimes, the feeding that happens below the surface is even more dynamic. The study of aquatic biology shows that most trout take the majority of their food (possibly 80%) below the surface of the water. Most of the larger trout do their hunting close to the bottom. Big trout hunt for big bites, and one of the largest prey items found in lakes are crayfish. Crayfish are found in most watersheds throughout the
United States. They live in both lakes and streams. In many lakes and reservoirs crayfish make up the bulk of fish diet.
Crayfish are bottom dwelling critters that are capable of swimming in short quick bursts, but spend most of their lives lumbering around on the bottom. Technically, crayfish are crustaceans and they are related to shrimp and lobsters. In the Pacific Northwest, crayfish regularly grow to four inches long, and their bodies are as large in diameter as a grown man's thumb. They have large claws to both defend and feed themselves. People think they are good to eat and they are considered a delicacy in much of the US. Trout and fishes such as bass think so too.
But what are crayfish really? If salmonfly nymphs grew as big around as your thumb, they might look a lot like crayfish. Crustaceans and insects have a lot in common. They both have exoskeletons, which means that their muscles are on the inside and on the outside is an armored skeleton; hard for fish to break into. So fish like trout and bass just swallow them whole.
For this reason, crayfish are out on the open bottom as little as possible, preferring instead to live within cover where they are difficult for fish to get. Crayfish will be found mainly under rocks or among the roots of both live and dead trees. Reservoirs which were logged before they were filled with water have many stumps on the bottom and are ideal crayfish habitat. Crayfish are predacious, and very territorial. They are also scavengers which are capable of eating just about anything that is organic. They, like insects, form a primary layer at the bottom of the food chain.
Most important to fishermen, they are a main source of protein for fish that are large enough to eat them. Crayfish can feed at all times of the day and night, and all year round. This makes them a very stable and reliable food source for fish and animals year around. Crayfish are protein packed meals that come in many sizes. Crayfish are as small as insects when they hatch from eggs, but grow large enough to feed large animals such as raccoons and even humans. By the time crayfish reach full adulthood, they are the size of a thousand mayfly nymphs. When trout can take their food in bites of this size they grow very rapidly.
Those are some of the factors that draw my attention to crayfish fly patterns. It is my theory that smaller fish tend to veer away from larger crayfish fly patterns. This is due to the fact that these flies are just too large for many fish. You tend to catch a bigger variety of sizes of smaller fish when using flies that represent insects than you do with flies that mimic crayfish. But remember that crayfish start out the size of insects and some of the fish you caught with your nymph patterns might have been mistaken for small crayfish. It is not hard to believe that certain wild trout may start eating crayfish when they are small and become crayfish hunting specialists.
When fish reach a large size, small insects are just to much trouble to feed upon. They need larger bites to get their interest. These fish ignore small food such as mayfly spinners or chironomids most of the time. Instead, they will actively seek out larger, calorie rich meals that are worth chasing, such as crayfish, sculpins, mice, and larger nymphs such as hexagenia, etc.
This means if you are using forage patterns like crayfish or sculpins, you can expect larger fish to be the ones that make it to the hook. You often don’t need to be totally specific with fly patterns or leader size while throwing these larger flies. Crayfish come in a variety of colors and sizes.
When fishing with flies that mimic crayfish around stumps or other heavy structures, I will use a larger test leader. I want the advantage of being able to stop heavy fish before they reach the structure, and because I hate losing $4 flies. Fish do not tend to be line shy in most cases when you are throwing a 2-3 inch long fly. I will typically use a 5 foot length of 10 pound Maxima Ultragreen on the end of my sink tip line when fishing snaggy water. In shallower water that requires a floating line to be utilized, I will use a 7-1/2 foot 2x or 3x leader. Retrieves are often the most vital part of fishing crayfish patterns. I have fished the same spot on a lake with at least 5 different flies in one day and caught fish on all of them using the same retrieve.
When I’m out on a large body of water that has some good depth to it, I like to fish my crayfish flies less than a foot off the bottom. I will use a slow long pull with a very short acceleration at the end of the strip. I then keep a tight line as the fly drops, because 90% of the time this is when fish will strike. And boy, do they! The strikes I get on this retrieve are so violent and so short, that I theorize the trout are trying to stun or kill the crayfish on the first few strikes. So don't be mad if the hook does not stick on your first set, the fish will be back in less than 2 strips and will hit it even harder, engulfing the fly the second time around. When in shallow water, I like to mimic a crayfish scurrying for the nearest rock, using short strips in quick succession. Often times you will find smaller, more enthusiastic trout, with a few larger ones mixed in.
Stripping crayfish flies past structure in mid-depth water is another fantastic way to target aggressive ambush-oriented fish. This is a very successful tactic to catch large brook trout in lakes. Oftentimes, if you see a stump or sunken log, which are common in mountain lakes, there will be a fish using it for cover. Be wary of small limbs protruding from the main trunk as these are fly catchers. Use a strong enough rod to pull fish out of heavy cover fast, because if you don’t, there is small chance of landing any.
Use a fast action five or even six weight rod with a stiff butt. Pair that rod with the full lake system as found in this authoritative article on Lake Lines.
As far as flies go, my top picks are Cayfish Bugz, Ritz’s Fighting Craw, Bead Head Wooly Buggers in brown and in olive, Sculpzilla in olive, and the Autumn Splendor. Whenever I go to a lake, I make sure my fly box is full of all the above. Take your time, fish slow, experiment with your depths and retrieves and you’ll be successful with crayfish patterns.