John Kenwood Second year recreation

Going wheelin’? Avoid riverbeds

The spawning habits of rainbow trout

  • Mon Apr 20th, 2015 5:00am
  • News

John Kenwood

Second year recreation, fish, and wildlife student at Castlegar’s Selkirk College

We have all noticed how much the water level in the Columbia River fluctuates. As the dams’ output decreases, whole new islands and gravel beaches get exposed.

With the appearance of new beaches, not only do we have more spots from which to fish, but apparently an even closer parking spot too.

Whether it’s for the thrill of driving where we normally can never drive or just a dislike of walking to our favorite fishing holes, we often see vehicle tracks all over the riverbed.

Unfortunately, this low water often occurs during the spring and fall, when the rainbow trout and kokanee salmon are spawning.

Rainbow trout spawn in the spring or early summer. Many swim up the smaller tributaries of the Columbia or Kootenay where they were reared while others remain to spawn in the big rivers.

When the spawning season begins, the males choose an ideal territory that is shallow but has a constant flow of water and guard it against other males. A female will select a male and his territory and begin digging her nest or “redd.”

She lies on her side and flaps her tail against the river bottom; assisted by the current to move away sand and gravel, she can dig a redd about two feet deep.

In this trench she lays her eggs and waits for a male to fertilize them. Once the eggs have been fertilized, the female buries the nest with some sand and gravel and swims away.

The eggs don’t remain in the gravel for long. About a month after fertilization they hatch and the fry move away from the nest. It can be difficult to pinpoint exactly when the eggs are vulnerable, but we know that before they are fry and can swim away, they are stuck in the gravel.

In the Kootenay region we have a large variety of freshwater fish that spawn at different times of the year. Chances are that at any time of year, there are spawning events going on and the gravel is full of fertilized eggs.

The kokanee salmon spawning in the fall is obvious to most observers, but others are much less so. Whitefish and lake trout spawn in the winter, westslope cutthroat trout in the spring, white sturgeon in the summer and bull trout in the fall. Several other species, such as sculpin, have been observed spawning at any time of the year.

In a system where the water level fluctuates, those eggs in shallow nesting areas are at risk. When the dam closes its gates, the nesting areas the fish have carefully selected are now exposed. Thankfully however, there’s more to the river than meets the eye. The current continues to flow a foot or two beneath the rocks, keeping most eggs alive.

The vehicles are a whole other matter. Driving on the riverbed, whether it’s for parking or mud bogging, compacts the gravel at least and tears it up at the worst.

Besides trucks, there are also ATVers ripping up dry riverbeds. Although many eggs can survive the low water, they can’t survive if the gravel is compacted or disturbed.

 

All riverbeds are a “no motorized access area.” However, we can’t expect  conservation officers to be everywhere; we have to police ourselves. So, even if it looks tempting, park it and go on foot. The more eggs that survive in the gravel, the more fish we have in the river to catch and enjoy.