Trout are cold-blooded creatures, and active in relatively cold water conditions. Generally trout need water temperatures between 35 and 75 degrees to survive. And just as in summertime angling, the stream thermometer will give you an idea of how productive winter and spring fishing may be (see the chart, below).
TEMPERATURE: EFFECT ON TROUT:
80c Lethal to trout
70 Trout seeking cold springs and tributaries
65 Feeding slow
60-63 Optimum temperatures
55 Trout become active & looking upward toward water surface
40-50 Trout sluggish, feed sporadically and look for food on stream bottom
IMHO, the ideal flies for cold water angling are such creations as the Killer Bugger, Midge and Worm imitations or any small dark kebari. But considering the chart, nearly anything that looks like a meal, and that sinks fairly well could mean success.
Try using a weighted kebari, but be sure to size it for the weight of the rod that you are using. Choose a copper wire under-body for lighter rods, shallower depths and warmer water. Move to a brass or tungsten bead head for heavier rods, deeper or colder water. The best tackle goal is to use the lightest weight kebari possible (given the conditions) to avoid any unnatural appearance.
Trout are less biologically active in cold water and won't move very far for a meal. Timing is important. If water temperatures have been steady, but then a cold snap drops them again, it's better to put the gear away and spend time with the family or play video games. Wait a few days for sun and high pressure to raise water temps again. Water temperatures often follow air temperatures but take a while longer to have any effect. A big however; if rising air temperatures cause snow to melt into the streams, it often has the opposite effect, chilling thing down again.
Rivers that have a fairly steady water flow usually fish best. Rapidly rising or falling water levels tend to turn trout feeding activity off, sending them to cover. Accurate casts to the most likely holding lies becomes very important. The most productive holding spots are under deep undercut banks and exposed roots or overhanging vegetation. Along with deep holes and plunge pools, these spots will often hold the largest fish in a stream.
The dead drift is the most common technique used in early season, and it often produces when other methods fail. The only difference between this and the traditional wet fly swing is the added weight of the kebari. Cast upstream and across, and allow the fly to swing past you and around at the end of it's travel. Be careful to fish it out completely and avoid the temptation to lift the kebari early for another cast.
Although dead drift is the most common technique recommended when the water temperature is less than 50 degrees, there are other methods which often prove more enticing to fish.
Try Casting upstream to allow the fly to sink, trying to keep it as deep as possible for as long as possible. When it is directly across from you, lift the rod about a foot then drop the rod and let the kebari drift another three to five feet downstream, then repeat.
The idea is to manipulate the fly a little, but at the same time keep it as deep as you can. Once the kebari gets to a point downstream it will rise to the surface as your line tightens. Although the fly is no longer deep in the water column, you should still fish it out as it comes to the surface. Then lift it for another cast.
If this slow motion effect fails after half a dozen tries, try a slightly faster raising and lowering of the rod, but still attempting to keep the kebari as deep as possible. If this trick fails, try a faster manipulation closer to the water surface. The idea is to give the opportunity for a trout to spot and move to intercept the fly near it's holding level.
The strike often comes during the movement of your fly, so stay alert for any change in line movement. The take may not be as evident as with later spring and warmer water when fish are more aggressive. Fish also tend not to hold the lure in their mouths very long in cold water so a quick strike will likely be needed.
These guidelines can change not only with the season, but also with the location in any stream. So to summarize, trying a variety of methods until the correct one for that location is found, is the expert anglers secret weapon. That combined with knowing where fish will hold in a stream, being aware of water temperatures and the skill to present your kebari to drift past a fish's nose.
PHOTO: Courtesy of https://pixabay.com/en/winter-fishing-fishing-snowbank-954075/