PINEDALE — The year 2020 is one many of us will remember, for better and worse.
The year will certainly be remembered for many things, but will it be remembered as the “glory days” of fishing on the upper Green River in Wyoming? Recent assessments of the Green River trout fishery by Wyoming Game and Fish Department biologists in Pinedale indicate the trout population is at or near an all-time high.
Every year, biologists monitor the status of the fishery by completing an electrofishing assessment within a designated reach of the river. Darren Rhea, a Fisheries Biologist in Pinedale, directs all of the work conducted on the Green River.
“We maintain a fairly rigorous monitoring strategy for the Green River,” said Rhea. “It’s an extremely valuable resource in the region and supports a lot of angler use.”
Rhea says its important that the WGFD keep a close eye on the fishery to ensure that it is not being over-utilized, or impacted from other factors. In the upper Green River (above Fontenelle Reservoir), six different reaches are monitored on a three-year rotation, with two reaches monitored each year to maintain a robust dataset going back several decades.
The process can be fairly complex. Large rafts and drift boats, specifically designed to carry generators and other specialized sampling equipment, will carry a crew of 2-3 people down the river producing an electrical field in the water, which allows for the effective capture of adult trout.
The process is repeated over a period of 3-4 days to generate an estimate of the total number of fish in the river based on a mathematical model that uses the number of captured and re-captured fish over the course of the sampling event.
The resulting population estimate, along with size-structure and species composition, provides managers with empirical data to evaluate the current status of the fish population and compare to previous years to monitor trends or long-term changes.
The effort in 2020 focused on two areas of the river, including one reach of the river near the Daniel Fish Hatchery and Forty-Rod Creek, and another below the Five-Mile Bridge area near Big Piney. Both areas have been sampled regularly for a period of 25+ years, and provide a good baseline for monitoring changes over time.
Historical data, dating back 30+ years, indicates that more trout used to inhabit similar areas of the Green, though most of them were small rainbow trout (< 9 inches) that were the result of widespread stocking which has since been discontinued. Wild trout now make up the vast majority of fish in the river and their numbers have never been higher.
One reassuring phenomenon Rhea has witnessed over the course of his career is a strong shift in voluntary catch-and-release angling on the Green and other popular river fisheries.
“During the summers of 2019 and 2020, we interviewed over 300 anglers fishing the Green River and not a single angler reported harvesting a trout, despite catching and releasing hundreds of fish,” Rhea said.
By all accounts, 2020 may well have been the “glory days” of fishing on the Green River. Unfortunately, Rhea doesn’t expect the phenomenon to persist.
“2020 was among the most ideal conditions for sampling trout in the Green River,” he said. “Lower than average flows added to our capture efficiency and contributed to very precise estimates.”
However, persistent drought conditions and low flows do not bode well for fish populations in the future.