By the time the last of the maple leaves drift down our rivers into the lake, river water temperatures will be approaching 4C. This means cold water fishing and the techniques required will be totally different than earlier in the season. This is the time of year when carrying a thermometer can really make a difference in angling success. A sudden cold snap causing a 1C or 2C drop below the magic 40F or 4.4C temperature will change locations where trout will be found and make trout lethargic until mid-day higher temperatures raise their metabolism. 

If the water temperature stays down for a couple of days, the fish gradually get accustomed to the lower temperatures and perk up a bit but they never strike and fight as briskly as they do above that important temperature barrier. Rarely do cold water rainbows jump with the zest and vigour that October fish exhibit at 10C and rarely, if the stream environment allows a choice, do they suspend in fast water.

For anglers who haven't been on our rivers since the temperatures dropped, November and December fishing conditions can present a considerable handicap. Instead of finding fish at the heads of rapids or in faster flows, it’s necessary to run slow and low in deeper water. In fact, colder water holds more oxygen than warm water so the fish are no longer in need of the extra oxygen provided when water is agitated at the surface by bottom obstructions.

For those who do check daily temperatures, cold water months can be more productive than any other time. When large schools of winter fish enter our rivers, they have a tendency to take their time moving upstream to wintering pools. A warm sunny day following cold overnight temperatures can result in a change in location, bait preferences and activity from daybreak to noon. Often it pays to wait until mid-morning to start fishing once the water is close to freezing.

Air temperatures change water temperatures more and faster on some streams than others though, as a deep, spring-fed stream’s temperatures vary less than an open stream that has miles of fast water, rapids which create lots of air-water interaction.
 

Bait and lure anglers can be more successful fishing with less subtle colours in cold waters, it seems that the bright, even fluorescent colours are needed to stir up those dozy winter fish. Hot pink and hot orange roe bags, intensely coloured body baits, spinners and spoons with real silver plating and splashes of red, all with high attention factors come into their own with the cold weather. Some lure manufacturers have even learned from west coast anglers and developed a colour chart advising what lure colours work best at different temperatures.

While an October rainbow often hits so hard and fast that the first sign of a bite is a fish somersaulting through the air, winter fish usually just stop your drift. After the hook is set, they sometimes pause for a second before reacting. An initial wobble and tug follows before they wake up and begin to fight. 

Still, some dandy fishing action is possible once the lake cools off. When this happens there isn't a big differential between the lake temperatures and the lower river temperatures to stun and stall rainbows attempting to move upriver. If a warm spell follows a period of cold nights and a surge of water flow calls in a big school of winter-runs, elbows can get sore from the action that takes place. A day when you hook a dozen or more big fish from a school of bright winter rainbows provides great memories.

You can think about them when winter storms are rattling windows and doors and wonder what you could have done to increase your landing percentages. But that’s another story.