Staff Writer Capital News
Sunday, September 25, 1994
Ironically, it’s a run for survival of the species but it means immediate death for the individual.
In an awesome phenomenon of nature, at three or four years of age land-locked salmon, or kokanee, join their sea-going brothers and sisters in an almost-unerring navigational feat to return to their place of birth.
Annually in September the glistening red bodies of mature fish flick upstream from the lake to complete their odyssey by spawning and then dying.
Each female kokanee lays 400 or so eggs in gravel beds in the streams in which they were born, and they are fertilized by the male.
Only 10 per cent will survive in natural situations the dangers from silting, which can smother the eggs; fluctuations in stream flow, which can disturb the gravel beds full of eggs; or freezing.
Environment Ministry biologist Bruce Shepherd says spawning channel fish such as those which hatch in the Mission Creek spawning channel have a doubled or tripled chance at survival.
The annual spawning run of the kokanee begins with the month of September, and often continues to mid-October, peaking about now; while shore spawners, a genetically separate stock, spawn about a month later, says Shepherd.
Over winter the eggs incubate in their gravel beds, water temperatures defining when they “button up” or use up their yolk.
By April or May accumulated thermal units (ATU) or the degree of freezing determines metabolically when they will develop eye spots and begin to hatch.
It all depends on external temperatures, Shepherd explains.
One night, when there are fewer predators about, the fry will emerge and head downstream and directly to the middle of the lake.
For the next three to four years the young fish will feed and grow in the lake, feeding at dawn and dusk on plankton, evading anglers and other predators, until it’s time for their homecoming.
By now they are 250 mm or 10 inches in length. Larger kokanee usually are sterile, although if there are fewer fish in a lake they will tend to grow larger, says Shepherd.
During the annual run interpretive tours for classes of students are held on both Mission Creek and Peachland (Deep) Creek, usually in the mornings, beginning at 9 a.m.
Members of the public are welcome to tag along on these tours which will continue until Oct. 7, says Shepherd.