But Trout Unlimited Council President Dave Sweet of Cody says the service is not doing enough.
Sweet said cutthroat fishing in Yellowstone has declined alarmingly since 1994.
Official documentation of lake trout in Yellowstone Lake began in 1994, and the Park Service's subsequent attack on the species started in 1995.
The 32-foot Freedom is built for gill-netting like its aluminum counterparts, which have successfully netted lake trout in the Great Lakes. Park Service employee and fish biologist Phil Doepke is at the wheel, while deck hands unleash nets or heave them aboard.
It takes about 45 minutes to chug from the Bridge Bay Marina to the site near West Thumb, but finally, Hannah Gundernan, a college student helping for the summer, works the winch that reels in the gill net.
Soon, squirming lake trout, from squirts measuring 6 inches to big fat lunkers close to 3 feet, are lugged in.
The gill net is just what it sounds like — a closely woven net that snags fish by the gills.
Like a fish trapped into a huge wad of tangled fishing line on shore, the snarled trout flop and gasp, their gills throbbing like red bellows.
It's an assembly line; Doepke and his crew of three deftly disentangle the fish from the wiry, plastic line with practiced efficiency. Three volunteers help, but their productivity pales in comparison to Doepke's adept hands.
With a thud like a deflated basketball thumping off the backboard, the fish are tossed into large tubs. Later, the fish are killed and their air bladders punctured so they will sink to the bottom in water over 200 feet deep. In this way, the trouts' nutrients are returned to the lake's ecosystem.
Seagulls loiter like trilling helicopters or bob on the swells like feathered corks to snatch morsels of fish.
Meanwhile, the boat, smelling of diesel and fish, rumbles like an idling tractor as it maintains steerage.
CDs are plugged into a player. Waylon Jennings and Willie Nelson warn mothers of the dangers of cowboy adulthood while employees sway easily to the music and the boat gently rocks to the waves beneath their feet.
They work hard at a grueling, glamourless task, but the college-aged crew and their captain never grumble. In fact, they are buoyant.
Their workplace, Yellowstone Lake, is an alluring navy blue. The shoreline is ringed by conifers, and the Absaroka Range glides in the distance like a giant ship with saw-toothed sails. Nearby is Mount Sheridan, seeming to rise from the lake with peaks shimmering under snow like a lake-born mirage.
Doepke has been gill-netting every summer since 2003.
“I came for this project,” Doepke said. “It is definitely the most disgusting job I've ever had,” he added, smiling.
Doepke said he loves the outdoors and working hard, and he is ardent in his effort to rid Yellowstone of lake trout.
The two Park Service boats harvest around 8,000 lake trout per week, both working four, 10 hour days. The commercial boat snags about 6,000 lake trout per week.
Today was an average day: 1,046 lakers, four cutthroats and one sucker snared aboard Freedom. They were able to release two of the cutthroats, according to Doepke's log.
Volunteer Dick Crysdale, who was a Yellowstone Lake fishing guide and ranger in the park, wrote a book, “In Yellowstone, Cutthroats and Me: A Fishing Guide's Autobiography.”
Crysdale said the Park Service should intensify efforts to purge the lake and its tributaries of lake trout. Nonetheless, he has a warm feeling today.“When I leave here after this trip, the greatest satisfaction I'll have is knowing that there are hundreds less of the lake trout to eat the cutthroat trout,” Crysdale said.