By Chad Robert Snyder
Pilot staff writer
Low water conditions in the Chetco River are not necessarily a cause for concern, according to Oregon Department of Fish and Wildlife Fisheries Biologist Todd Confer, but they do cause an unusual situation for Chinook salmon that have yet to make their way to preferred spawning areas.
"Most of these fish are destined for the tributaries, but they could be forced to spawn in the main steam," Confer said.
At issue is water flow, which currently allows access to the lower Chetco, but not to the upper branches where salmon prefer to spawn.
The Chetco's cubic feet per second (cfs) measurement has plummeted in the last month due to a lack of sustained rainfall. The figure now hovers around 750 cfs (Thursday's measurement was 744 cfs) , which is off the 38-year average by about 2400 cfs.
This could also mean there are numerous fish waiting to return return from the ocean, Confer said.
"They don't have incentive to come in," he said. "The bulk of the fish spawn in December, so we know all the fish aren't in yet."
According to Confer, the concern is not that the Chinook won't be able to spawn, rather they may be forced to bury their eggs in less than ideal locations.
"Survival rate is typically lower in the main stem due to (eggs) being scoured out or buried," he said.
The waters in the main stem tend to be more turbulent, and as a result fertilized eggs (reds) can easily be washed out or buried deep enough they either won't hatch, or the fry, if they do emerge, will be unable to get into open water and will die.
If the bulk of the remaining Chinook are forced to spawn in the main stem, weather conditions for the duration of the winter will come into play.
"If we have a moderate winter the survival rate will be higher," he said. "If it's a wet season, it will be lower."
Again the issue is flow. According to Confer, higher, faster waters will mean many more reds being washed away or buried.
Another concern associated with low flow is predation. Salmon trapped in lower water are, "susceptible to being harassed" according to Confer.
Confer is watching the situation, but as of now he said it's not critical.
"We're not looking at a conservation issue yet," he said.