Game and Fish biologists battling goldfish invasion in northern Wyoming - Buffalo Bulletin

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Game and Fish biologists battling goldfish invasion in northern Wyoming - Buffalo Bulletin Posted: 15 Apr 2020 03:34 PM PDT POWELL — Fat rainbows pushed through the shallows at East Newton Lake, ignoring a team of biologists working just a few feet away from the deck of an aluminum jon boat. Their iridescent pink and purple hues caught the morning light, thick tails propelling the trout along the rocks. Wyoming Game and Fish Department fisheries biologist Jason Burckhardt, standing in calf-deep water, pulled one beauty after another from a faded blue tub. He measured the fish and took samples while two seasonal fisheries technicians, Haleigh Sever and Seth Anderson, recorded data, weighed and released the fish. About once every four years Game and Fish Cody Region fisheries biologists conduct estimates of rainbow trout abundance in the trophy, catch-and-release lake. In spring, rainbows are cruising the shoreline looking for places to spawn and are vulnerable to trap nets. Meanwhile, at West Newton Lake, three scientists toured the shoreline, electrofishing for goldfish and deploying equipment that should help find large groups of the invasive species in a continuing fight to both rid the lake of the former pets and keep them from spreading to the trophy fishery next door. The work of the two teams comes at a time when water levels continue to rise at West Newton, spilling into East Newton. Before the water started to rise a few years ago, the area Burckhardt's team worked in was dry. Now it's so high, the road to East Newton is closed, limiting access options. At West Newton, the parking lot and picnic tables are submerged and high water forced the removal of a permanent bathroom facility two weeks ago. And a new barrier has been built to keep fish from traveling between the two very different fisheries. West Newton is a well-stocked put-and-take lake where fishermen can catch up to six Yellowstone cutthroat trout a day to take home for dinner. East Newton is a trophy catch and release fishery featuring tiger, rainbow and brown trout. An earlier barrier is largely submerged at this point, but the new barrier between the two lakes is several feet high and should work well into the future. While Burckhardt's team worked, Cody Region Fisheries Supervisor Sam Hochhalter, biologist Joe Skorupski and Aquatic Invasive Species specialist Alex LeChemimant toured the shoreline of West Newton in search of goldfish. The pets-turned-pests were released to the lake by a "bucket biologist" more than five years ago. Goldfish were also discovered in the recently refurbished Renner Reservoir. "It's incredibly frustrating," Hochhalter said. "Not only does it compromise the quality of the fishing opportunity, but it consumes our time. Rather than us spending time to monitor and improve management of existing sport fisheries, we're now faced with more suppression and more consideration how to deal with this illegal introduction." Game and Fish spent nearly $325,000 refurbishing Renner. The lake was stocked with largemouth bass just last year, marking the long-anticipated opening of one of the few warm-water fisheries in the Big Horn Basin. Goldfish grow much larger when released into the wild and reproduce quickly, disrupting the ecosystem, Skorupski said in a recent department release. "Under the right conditions, goldfish will take over a fishery, binding up resources that could be used by other species, like largemouth bass," he said. The goldfish in the two lakes are growing quickly, "with mature individuals averaging about 12 inches, but can grow to 19-23 inches." Once mature, the invasive fish are too large to be preyed on by largemouth bass. "This is not ideal for the fishery or anglers seeking an outstanding fishing experience," Skorupski said. Thursday was day one of a multi-day effort leading through spring and into early summer at West Newton. LeChemimant deployed temperature loggers, enabling teams to hone in on the water temperature goldfish concentrate in when starting to spawn. Armed with the information, the crew will know when catch efficiency is going to be highest and they can start to remove goldfish with minimal effort. The team spent the morning electrofishing for goldfish to look at age composition and patterns of recruitment, as well as looking at diet overlap between the stocked cutthroat trout and the invasive species. "We'll be monitoring temperature throughout the season as we continue to sample," LeChemimant said. "We're going to try to pinpoint when these fish are spawning so we can increase sampling efforts in the future during those times when the fish are kind of bunched together." Goldfish have been in West Newton reproducing for years, but the effect on the habitat is unclear. "We have yet to really see a change in the performance of our cutthroat fishery," Hochhalter said. The team is interested in learning what goldfish introductions mean in different ecosystems, he said, because "future illegal introductions are inevitably going to happen." All is not lost at this point and there are options other than draining West Newton and Renner and starting from scratch. Biologists may be able to deploy sterile tiger muskie in the lakes as predators of the goldfish, but not permanent additions to the lakes. And while water levels continue to rise — a pain for those seeking access — nutrients from the flooded shores are sure to result in a growth spurt for the trophy trout fishery in East Newton. Members of the Cody Anglers Group want to work with legislators to get the state to stop sales of non-sterilized aquarium fish. The group has previously worked with local representatives to increase penalties for illegally introducing invasive species. The East Yellowstone chapter of Trout Unlimited and the Cody Anglers Group have also funded signs warning of the new penalties. "Because an illegal fish introduction can have disastrous impacts to a fishery, even an entire watershed, the crime carries some of the highest penalties that exist for wildlife violations," Skorupski said. Making sales of fertile aquarium pets illegal could possibly help stop their introduction and spread in area lakes, but Hochhalter is unsure if future legislation is possible. "While it makes sense from my profession," he said, "I can't speak to what that would mean for others who really enjoy having fish swim in an aquarium or bowl in their house."

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