Wondering if that new net at Elkhead Reservoir is doing its job?
July 1, 2017
Installed last September, a net designed to keep non-native, predatory fish at Elkhead Reservoir from entering the Yampa River appears to be fulfilling its purpose, though it may be too soon to tell.
This spring, Colorado Parks and Wildlife conducted its first count of the two species of concern, northern pike and smallmouth bass, in the stretch of water between the net and the spillway, where water leaves the reservoir and enters Elkhead Creek, which feeds into the Yampa.
"In our first sample this spring, we didn't see any indication that the net was failing," said CPW Aquatic Biologist Tory Eyre.
The count was taken before the reservoir filled with spring runoff and water began spilling over the spillway. Another count taken this fall, after the reservoir is done spilling, will give biologists an even better idea of how the net is working.
"This is a big spill year," Eyre said. "When it's spilling, it can suck trees and other debris through, damaging the net."
Officials are hoping the net, made of a sturdy polyethylene mesh, will hold up to any debris that gets swept its way, and divers will check and clean the net once a year.
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The net is one piece of a multi-pronged approach to protect four species of endangered fish in the Yampa River, the humpback chub, bonytail, Colorado pikeminnow and razorback sucker.
"They were starting to track amount of escapement from reservoir (of northern pike and smallmouth bass) and… our biologists determined it was far in excess of what we wanted to see," said CPW spokesperson Mike Porras.
The net will hopefully keep the predatory fish contained, but with so many factors affecting the species, biologists won't necessarily be able to determine the precise impact of the net on endangered fish populations.
"There's too many variables to directly link the net to the recovery of the endangered species just by sampling downstream," Eyre said. "What we can track is how many fish we are preventing from reaching downstream if the net holds."
The life span of the $1.2 million net is only estimated at about seven years, Eyre said, which is why CPW is also hoping to check northern pike and smallmouth bass populations through its new, annual Elkhead Reservoir Fishing Classic.
"(The net) is not a permanent solution," Porras said. "We also need the public to cooperate and help us out and help reduce the number of non-native predators."
The tournament began June 24 and ends Sunday. As of Friday morning, the tournament had 275 registered anglers who had caught just over 1,000 of the targeted fish.
"Next year we'll start tracking was that a significant enough portion taken by the tournament to make a population level change" and meet management goals, Eyre said.
CPW biologists are using the tournament to get a population estimate, and hope it will become a regular, effective management tool that meets both the needs of anglers and the need to protect fish populations downstream. Officials are also now stocking the lake with largemouth bass, which are less threatening to native fish downriver.
Contact Lauren Blair at 970-875-1795 and follow her on Twitter @LaurenBNews.