Life is pretty simple for trout and char living in productive stillwaters. Ideal habitat consists of access to easily available food sources which are in close proximity to the protection of deeper water. The drop-off area offers both, which in the end, benefits trout by conserving their energy for other life activities. Biologically, the drop-off includes the area from the edge of the shoal or littoral zone to the start of the deepwater zone. It is the transition area that is sloping off to the deepest parts of the lake. It is the last zone of habitat that is under the influence of the sun and the benefits of photosynthesis. Drop-offs can range from long, gradually deepening slopes to short, abrupt almost cliff-like drops to deep water. The deepest edges of drop-offs would be up to 25 feet in depth.
The typical drop-off supports the growth of a variety of aquatic plants. Lush stands of pondweed, native milfoil, coontail, lily pads and chara all provide excellent habitat for both fish and their food sources. This includes such common food items as dragonfly and damselfly nymphs, mayfly nymphs, caddis larvae, chironomid larvae, leeches, scuds, forage fish and snails. Trout and char seek out the larval, nymphal, pupal and adult stages of the aquatic insects as well as forage fish and other available invertebrates like leeches and scuds.
The drop-off is ideal trout habitat not only because of the availability of food but also the provision of safety from predators. Constant feeding on the shallower shoal areas of the lake leave fish vulnerable to their natural predators such as ospreys, loons and other animals. Feeding along the slopes of the drop-off allow fish a quick escape into deep water. The drop-off increases in importance during the warm summer months. As water temperatures increase the shoal zone can become too warm for trout to inhabit at least during daylight hours. Warmer water also supports less oxygen which is a bad combination for cold blooded trout. The drop-off becomes a summer refuge where the water is cool and oxygen levels remain ideal for trout to continue feeding and living in comfort. Fish can often be seen swimming along and parallel to the face of the drop-off slope. Other times they can be seen moving up and down the face of the slope. Trout swimming actions are often in response to the movement patterns of particular food sources being targeted.
Floating, sinking and sinking tip fly lines all have their place in presenting flies to trout living in this transition zone. Anchoring location in relation to the drop-off also has a bearing on fly line selection and presentation techniques. A favoured position is to setup along the inside or shallow edge of the drop-off with flies being cast and retrieved out over and perpendicular to the sloping lake bottom. Flies are worked up the slope face towards the edge of the shoal. This works well with emerging dragonfly, damselfly and mayfly nymphs and caddisfly pupae bearing in mind where in the water column each of these emerging insects are active. Anchoring along the face of the drop-off and working flies parallel to the slope can present flies to a lot of potentially cruising and feeding fish.
A depth sounder preferably with side scanning is a big help in seeing the lay of the land so to speak. Not only will you know the depth when anchored but also the depth which flies are being fished over. A side scan can mark fish swimming in the area being fished.
The deeper parts of the shoal are suited for full sinking lines with the goal of matching line sinking rate with depth being fished so that flies get down to the targeted zone. Calculate the wait time based on the sink rate of the line to ensure the desired depth is reached before beginning the retrieve. The RIO In Touch sinking lines built with a no stretch core are extremely sensitive in detecting bites.
Drop-offs provide year round habitat in terms of food and cover for trout and char. Learning how to approach and fish drop-offs solves a big part of the stillwater fishing puzzle.