Low water levels harming salmon run

Low water levels harming salmon run, eagles' dinner

Oct. 31, 2000

By Jim Mimiaga
Journal Staff Writer

Historic low levels at McPhee Reservoir are impeding the yearly spawning efforts of kokanee salmon on the upper Dolores River, reports the Division of Wildlife.

Kokanee salmon season delayed

Snagging for Kokanee salmon has been pushed back this year because of low river and reservoir conditions that are blocking spawning efforts.

The Dolores River is closed to snagging until Nov. 15, reports the Division of Wildlife, to allow time for biologists to harvest what they can for stocking purposes. Those with a valid Colorado fishing license can snag for salmon in the Dolores River between Nov. 15 and Dec. 31. The bag limit is 40 fish per person with a license.

Right now in order to give the fish a chance to spawn up river and lay eggs, no snagging is allowed in stream of the Dolores River. Officials remind anglers that this goes for any place the river is clearly flowing, even where it is moving within the reservoir basin, as it is doing now.

Snagging is allowed only in standing reservoir water, not in a river channel where water is flowing. The DOW reminds people that permission is needed to fish off of private property.

"We have been monitoring it and the fish are very late in entering the spawning run this year," said Mike Japhet, fish biologist for the DOW, on Friday. "Usually they are moving up by mid-September."

A relentless drought and heavy irrigation demand have left McPhee at its lowest level since it filled in 1988.

The lack of water has uncovered the silt build-up and mud flats that accompany any reservoir, but which are problematic for fish.

Japhet speculated that the resulting muddy river flow has blocked the entrance to traditional spawning areas for the hundreds of salmon now staging at McPhee’s inlet near the town of Dolores.

"I suspect that the mud has inhibited the kokanee from running somewhat; the muddy waters can cause confusion for the fish," he said. "Shallow conditions might also be a problem for them getting upstream where they need to be."

Kokanee have a strong migratory instinct, but they also rely on smell and taste for guidance upstream, a process affected by murky waters, Japhet said.

As the reservoir level drops, the Dolores River "re-discovers" its old channel, slicing through the deposited layers of exposed fine sand and carrying it along for two miles before backing up into McPhee where it settles out. During normal years the silt sits undisturbed and hidden under standing lake waters.

The dry summer and new river course have pushed back the boundary of McPhee significantly plus altered the kokanee salmon harvest schedule this year.

Considered as another consequence of the drought, the missing salmon may mean no big harvest this year for area residents. Typically the DOW gives away salmon at Dolores Town Park this time of year.

"The give-away is postponed indefinitely until they show up," Japhet said.

The lack of spawning salmon will lower the amount of eggs harvested by biologists for rearing in the Dolores River fish hatchery, he said.

Using a process called imprinting, every year 150,000 eggs are hatched, and then the young fish, called fry, are released back into the Dolores River spawning grounds.

They swim into McPhee, mature in three to four years and then automatically return and reproduce at the same spot they were released, making it convenient to harvest eggs again.

But thanks to an salmon-egg-sharing agreement with other area reservoirs such as Vallecito north of Durango, and Blue Mesa near Gunnison, McPhee will be stocked as usual in April with young kokanee.

"We probably won’t have a very successful egg take this year from the Dolores, but they will be replaced with eggs from elsewhere and then released," Japhet said.

In a spectacular display, sexually mature Kokanee move up the Dolores River to lay eggs, and then die en masse.

During this process a bizarre metamorphosis occurs where the salmon’s lower jaw is dramatically extended and the body becomes mottled, rotting away as the fish dies.

The absence of salmon also means fewer bald eagles will stop over on their way south. Typically dozens of the stately raptors can be seen perched in the cottonwoods preying on thick salmon schools below.

As winter approaches, wildlife officers say, the popular spectacle will be diminished as the birds hurriedly fly on towards warmer climates.

Recent rains should give the salmon some reprieve by raising the low river level, which has been flowing between 65 and 70 cubic feet per second this summer. Monday it was pushing 100 cfs.