Next-generation kokanee salmon thriving at Blue Mesa
Late December finds snow and ice covering most of the Blue Mesa Reservoir basin, but many anglers still carry mental images from the summer of vast expanses of dewatered shore and a Gunnison River reduced to little more than a trickle.
Even when it’s less than half full (39 percent as of Dec. 23), this 29-mile-long reservoir is a vast storehouse of angling resources, perhaps none more important than the kokanee salmon.
Anglers come from all over the state to fish for kokanee salmon, and in most years it is the salmon from Blue Mesa that supply future generations of salmon for fisheries across the state.
This year, in spite of reservoir levels not seen since the drought of 2002, sufficient numbers of kokanee salmon negotiated the low water of the Gunnison and East rivers to ensure plenty of next-generation salmon for Colorado anglers.
Around 16.3 million kokanee eggs were harvested statewide, said Dan Brauch, area fisheries biologist for Colorado Parks and Wildlife in Gunnison.
“This year we got about 13.1 million eggs (from Blue Mesa), which is two years in a row we’ll be able to meet our statewide stocking requests,” Brauch said. “Our fish requests (from other aquatic biologists) is 12 million, so we try to make our egg take at least 20 percent over that, around 14.5–15 million.”
That 13.1 million from Blue Mesa exceeded the previous high mark of 11 million eggs set in 2011, according to the Colorado Parks and Wildlife website. Twenty-seven state waters will get juvenile kokanee salmon next year.
Brauch said while Blue Mesa carried most of the load this year, in years past when the Blue Mesa harvest was down, other waters have been relied upon to make up some of the loss.
“A lot of years Blue Mesa has supplied the major portion of eggs, but in 2009 we really were depending on the other units,” Brauch said. “We spawn kokanee at a lot of small places, but their potential is limited because they are so small. This year we got about 3.2 million from places other than Blue Mesa.”
“There aren’t many big reservoirs like Blue Mesa and Granby that provide a large numbers of eggs. Having other places to spawn a couple million eggs is certainly needed.”
A salmon “trap” at Wolford Mountain Reservoir near Kremmling yielded about 1.9 million eggs, Brauch said, “but other waters didn’t do so well.”
Granby’s kokanee population is slumping, and this year the reservoir gave up less than 1 million eggs.
Biologists got about 250,000 eggs from Vallecito Reservoir near Durango but struck out at McPhee Reservoir near Dolores.
A recent story in the Cortez Herald newspaper reported low water levels in the Dolores River posed too great an obstacle for salmon to move out of McPhee.
“The run has been virtually nonexistent,” Jim White, an aquatic biologist with Colorado Parks and Wildlife, told the Herald. “The way (McPhee) deposits sediment in dry years, it creates a shallow, delta-like area where the river meets the lake. In effect it blocks the salmon from migrating.”
In the story, White said a similar block happened in 2002, when “layers of mud, silt and debris made the river impassible” for spawning salmon.
White said only about 150 fish made it through to spawn, a far cry from the 10,000 that may spawn in good years.
Brauch said low water flows didn’t seem to hinder the fish in their 20-mile jaunt from Blue Mesa to Roaring Judy state fish hatchery about 12 miles north of Gunnison.
“Not really,” he said in response to a question about potential hang-ups. “It didn’t create any barriers for kokanee, anyway. They can work up some fairly small water; they only need 6–8 inches of water to work through, and most of the river is large enough to accommodate that.”
He said Parks and Wildlife installed a screen on the East River to prevent kokanee from bypassing the hatchery.
“After we built a new raceway at the hatchery, at first we had trouble getting salmon to go into the raceway,” he said. “But putting the screen in the river made a huge difference.”