Grand River - Raising Rainbows
Rehabilitating a tired, industrial river
Fat, robust, brown trout and rainbow trout are now caught by fly fishers in
riffles and pools that once were poisoned with industrial and domestic sewage.
The people who live along rivers pollute them, often with little regard for the river's
health. The water quality of the Grand has suffered over the years, and the Grand River Conservation
Authority has spent the last decade trying to improve it. One of the main goals is to increase
habitat diversity, because any cold water stream that can support a wide diversity of aquatic
life is a healthy one. Cold water streams are those with temperature ranges of 18 to 20 degrees
Celsius. The survival and health of trout are one of the best indicators of a stream's condition.
There are three consecutive steps in rehabilitating of a stream to make it suitable for
trout. The first involves removing accumulated debris, whether natural or human made. Vegetation
along the banks may be cut back to let the water flow faster and to encourage root growth
which stabilizes the banks. Beaver dams and obsolete man-made dams are removed. Such dams
collect silt, increase the water temperature and slow the stream's natural rate of flow.
The second step involves enhancing the stream's natural flow. When the natural channel of
the river takes shape after flushing the sediment and exposing gravel beds, the channel can
be stabilized by building flow deflectors of rocks, brush, or log cribs to guide and maintain
the natural flow. Sometimes cedar "sweepers" are installed along weak parts of the bank.
The cedar branches trap waterborne silt, and this starts to rebuild the bank. Grasses and
trees are planted along newly re-established banks to stabilize them.
The third and final step involves improving the habitat for trout, which need clear, clean
water that is rich in dissolved oxygen. Trout like to shelter under overhanging banks, so
artificial overhangs are created where needed. Often rocks are added to the stream so that
fish can rest behind them, out of the direct force of the current.
Gravel is added to the stream to provide fish with a place to spawn. Fish build nests for
their eggs by swishing their tails over the gravel beds to make small depressions called
redds. The eggs are deposited in the redds, fertilized by milt from the male, and then dropped
into the gravel where they are protected against predators until they hatch.
Today, brown and rainbow trout can now reproduce naturally in sections of the Grand River
and its tributary streams. However, the river has become well known to anglers in Canada
and the United States, and is now heavily fished. Most fly fishers are encouraged to release
their catches alive, through special angling regulations and education programs.
Trout stocking continues, however, and wild strains are now being introduced to supplement
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