It's a spring
ritual observing Canada
Geese defending mating territories and watching grown men in small
aluminum boats trying to break up ice on an interior lake. Yes, spring
is in the air and these anglers are jumping the gun a little but with
good reason. They know the incredible fishing that can occur during the
first few days after the ice has left or is leaving a lake.
Brian Chan
In order
to understand why fishing can be so good we have to step back and understand
the changes that have occurred under the ice during the long winter season.
Most small interior lakes are covered with ice and snow for between 5
and 6 months. During this period there is little if any replenishment
of oxygen. Green plants die-off and decompose due to the lack of sunlight
and photosynthesis. This composting of plant matter also utilizes oxygen.
As winter progresses the amount of available oxygen decreases. By late
winter the highest concentrations of oxygen are often confined to a band
of water that is sitting immediately below the ice. This zone of well
oxygenated water may be as narrow as 5 to 10 feet deep. Below this zone
oxygen levels may not be sufficient to support fish live.
Black Bead Head Chironomid
Photo courtesy of Ron Boudreau
As the ice
leaves a lake this stratified layer of well oxygenated water remains in
place. The lake will not de-stratify or mix until the water temperature
of the lake becomes similar. A strong wind will then mix the entire water
column resulting in a process called turnover. It usually takes 7 to 14
days for lake temperatures to equalize and initiate the turnover process.
Trout are therefore confined in these shallow water zones until turnover
begins. Fishing action can be fast and furious during this ice-off period.
The shallow water areas of the lake begin to warm under the early spring
sun and trout become aggressive feeders. In some instances trout will
literally attach anything that is cast into the water but in most instances
they are looking for more familiar food items. Water boatmen are very
active at ice-off and are a favored food item. Watch for them diving into
the water, followed by big boils of trout as they intercept the swimming
insect. Other good ice-off fly patterns to try are
chironomid larvae and
pupae , leeches
and shrimp
. Chironomid larval patterns are always a good bet early in the season
even though the water may be too cold for any chironomid hatches to occur.
The larvae over-winter in the mud at the bottom of the lake and get active
as the water starts to warm. Chironomid larvae are often a reddish/maroon
colour and are known as bloodworms. Make sure these flies are fished dead
slow and as close to the bottom of the shoal as possible. Normally, the
first chironomid hatches to occur are those very small species i.e. #18's
and #20's. In most cases it is not necessary to fish pupa that tiny but
try at least patterns tied on #14 and #16's. Leeches and shrimp are standard
trout food fare at all times of the year so are good bets for ice-off.
Bead-headed leech patterns offer a nice undulating motion through the
water and are often the ticket to getting early spring trout. Shrimp patterns
tied out of plastic chenille or other flashy synthetic materials seem
to work better at this time of the year. It is often that little extra
flash or movement that will trigger a strike. Slightly faster retrieves
are sometimes more productive with these brighter or bead-headed patterns.
Floating
and intermediate sinking fly lines work best for covering the shallow
shoal zone where these fish are concentrated. While there is minimal aquatic
insect activity occurring, early spring fish will show themselves by jumping,
surging through the water or dimpling at the surface film. This non-feeding
behavior will at least locate active fish. Ice-off fishing often sees
two or three short feeding periods spread over the entire day. Some of
the most intense movement occurs late in the day and just prior to last
light. The message here is to be patient and be prepared to fish until
dark. Ice-out fly fishing can be a great way to begin the stillwater season.
It is a relatively short phenomena that ends with the onset of turnover.
A lake in turnover will not fish well for at least 7 to 10 days. This
major mixing event changes the water chemistry of the lake to the point
where fish may become quite stressed and stop feeding until the water
quality improves. The sure sign of a lake in turn is very murky water
with large amounts of plant material and bottom debris floating in the
water column. If presented with this problem select another lake either
much higher in elevation that has not yet mixed or go lower to a lake
that has already completed turnover.
