A new study says endangered razorback suckers upstream of Lake Powell may struggle to migrate up the San Juan River to spawn. The fish are blocked by a waterfall that formed two decades ago when the river changed its course. KNAU’s Melissa Sevigny reports.
Scientists used radio tracking tags to count the endangered fish trapped downstream of the waterfall. They found few Colorado pikeminnow, but nearly one thousand razorback suckers.
Fish biologist Nate Cathcart, the study’s lead author, says, "Right now it does seem that based on their condition—their spawning condition and their maturity—as well as just the sheer abundance of the razorback sucker, that it does look like a spawning migration is being blocked."
Cathcart says future research may reveal if the razorback sucker will adapt to spawn in the reservoir instead, or if the fish need to be captured and shipped around the waterfall. In recent years Lake Powell’s level has been too low to submerge the waterfall and reconnect the river.
The study appears in the journal River Research and Applications.