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O Christmas Tree, O Christmas Tree

January 21, 2011 | by Bruce Auchly

Volunteers and FWP workers place used
Christmas trees on Tiber Reservoir. The trees
provide spawning habitat for perch.
Photo from FWP.

Christmas is so over. The holiday cards are in the landfill by now. Most of the toys are broken or ignored.

Then there is the Christmas tree. Gone, but depending on how it was disposed of, maybe not forgotten.

For years, fish biologists working with anglers and other volunteers have bundled and weighted donated evergreens to sink in reservoirs and lakes for use as fish habitat.

The city of Helena sinks thousands of weighted Christmas trees each year in Canyon Ferry Reservoir, which considering the size of the reservoir is a like a drop in a minnow bucket.

Real Christmas trees that is, not the artificial ones and nothing flocked, thank you. And what is that flocked stuff, anyway?

In north central Montana, fisheries biologists say the sunken trees provide spawning habitat for substrate spawners so they can drop their egg skeins and leave. Translation: the trees provide a spot where perch, primarily, can deposit their eggs.

Yellow perch, not native to Montana, lay their eggs in long sticky threads, or skeins. The skeins are actually long gelatinous strands with accordion-like folds. The skeins can reach seven feet in length and contain about 200,000 eggs, though most are much shorter with something like 25,000 eggs.

Shortly after ice out in early spring when water temperatures are in the 44-52 degree range, male and female perch head to spawning sites. Perch seek out spawning sites in shallow water with submerged vegetation. A female will expel her eggs and a male swimming close by will fertilize them by releasing a cloud of milt. Then they swim away.

The skein of eggs falls until ideally it drapes over submerged vegetation like a discarded Christmas tree, and eight to 10 days later tiny perch emerge and drift away. Perch eggs that fall into the mud and silt on the bottom often smother and die.

Perch are the target because they are a vital food source for walleye.

In Tiber Reservoir north of Great Falls, the effort is more modest than at Canyon Ferry Reservoir: about 800 trees annually versus 5,000. That’s because Tiber is more remote and a hauling company has to be hired to bring the discarded trees to water.

Canyon Ferry next to Helena provides a better and environmentally sound practice for the city to rid itself of evergreens rather than chipping them up for mulch or the landfill.

No matter where it happens, the practice is the same. Trees are bundled, usually two to a pair of concrete cinder blocks. Then the bundles are hauled onto the ice in early March, as close as safely possible to ice out.

Once the ice breaks up, the bundles sink and nature takes over. While the needles will fall off after a year underwater, the branches can last 10 years or more. That’s important for a reservoir like Tiber that has very little submerged vegetation.

So next year, don’t just throw that Christmas tree out by the curb. Find a place to donate it and wish a perch Merry Christmas.