Cross it off your fish list: First pikeminnow conquers river ladder

Cross it off your fish list: First pikeminnow conquers river ladder 

Cross it off your fish list: First pikeminnow conquers river ladder

By Gary Harmon
Thursday, September 4, 2014

A Colorado pikeminnow has become the first of its species to make its way up the fish passage in the Colorado River to the Grand Valley Water Users Association roller dam, where it was collected and released to travel upstream, possibly to the top of the pikeminnow’s range near Rifle.
The fish, which turned up Friday in the collection area of the roller dam, is significant for several reasons, said Dale Ryden, project leader for the U.S. Fish and Wildlife Service’s Colorado River Fishery Project.
“Now we know that this particular species can negotiate this particular fish ladder” at the roller dam, Ryden said. “The efforts we have put in to provide passage for this species in the Colorado River upstream of Grand Junction have not been in vain.”
The fish passage was completed in 2004 and cost about $4.8 million to build. [$4.8 Million and 10 years? Only the government could see that as successful. DGP]
The fish, which was about 23 inches long and of indeterminate sex, was estimated to be 5 to 8 years old. It was untagged, meaning it is was wild.
No other pikeminnow have negotiated the path to the roller dam and into the fish passage yet, though three other species — razorback sucker, bonytail and humpback chub — already have done so, Ryden said.
The so-called 15-Mile Reach of the Colorado River through the Grand Valley up to De Beque Canyon is already well-known as an important spawning and breeding area for the pikeminnow, the largest of the minnows and the top native predator of the Colorado River through its range.
The pikeminnow’s travels into the waters above the diversion dam, which was completed in 1916, will give biologists a chance to learn more about how the fish might have lived in the upper reaches of the range before the diversion dam and the Price-Stubb dam below cut off their access upstream, Ryden said.
It’s hoped that other pikeminnow will follow the example of this first one and find their way through the diversion dam and into the 40 to 60 miles of potential native range unseen by the species for nearly a century. Before the dams were built, only cooler water near Rifle limited the range of the fish.
“Fish tend to find other fish, it’s the nature of the river,” Ryden said, adding that if the fish found on Friday remains above the roller dam, it might emit pheromones that would attract others of its species to higher reaches of the river.
While this marks the first time a pikeminnow has negotiated the Grand Valley fish passage, pikeminnow long ago mastered the Redlands fish passage on the Gunnison River in Grand Junction.
As many as 17 pikeminnow have passed through that collection facility so far this year, exceeding the previous annual high of 12.
“We’re seeing a slug of young fish that are being collected for the first time,” Ryden said.
The Fish and Wildlife Service also has noted more than 20 razorback suckers passing through the Grand Valley fish passage. The previous high in any year was two.