Scales and feathers. Water and air. Fish and, well, fowl.
Yellowstone cutthroat trout and American white pelicans are an unlikely duo for conservation. They both inhabit the Blackfoot Reservoir, a and sun-soaked angling and boating destination in southeast Idaho. Both the trout and pelican are native to Idaho and depend on the land for survival. The fish can be identified by its bright golden hue. As for the bird—with that bill, how could you miss it?
This is a story about the delicate dance between a fish and a bird, and the challenges fish and wildlife managers face when managing two cohabitating species. It’s also a story about partnerships, perseverance, and a precarious balancing act, and a nascent—and blossoming—success.
A Fish in Peril
The most striking thing about the American white pelican might be its fabulous, pouched bill. Massively long and yellow, the pelican’s bill is perfect for scooping and swallowing fish. Squadrons of pelicans can work together to move fish into shallow waters where they feast on fish. They are among the birds in the Blackfoot Reservoir that feed on Yellowstone cutthroat trout.
The Yellowstone cutthroat trout is an iconic native fish in the Intermountain West. Bears, birds, river otters, and other animals depend on the trout for sustenance. Anglers have fished this species for generations. A combination of factors, including , water quality, and low water levels, have reduced the number of Yellowstone cutthroat trout throughout their range.
In early 2002, Idaho Fish and Game (IDFG) grew concerned about how increasing numbers of pelicans were interacting with fish in the Blackfoot Reservoir. Biologists were initially interested in predation on rainbow trout, a stocked game fish for anglers, but early study results turned the focus to Yellowstone cutthroat trout.
Dave Teuscher, Chief of the Wildlife and Sport Fish Restoration program in the U.S. Fish and Wildlife Service’s Pacific Region, formerly worked in IDFG’s Fisheries Research and Management programs. Teuscher and his colleagues began monitoring the numbers and eating habits of the pelicans in 2002 by sifting through regurgitated matter from pelican chicks. It smelled just like it sounds: fish, feathers, and a bit of bile.
“The smell wasn’t great,” Teuscher said. “We also occasionally got hit with droppings from thousands of gulls flying overhead. You’d want to wear a raincoat and carry an umbrella.”
When biologists from IDFG looked at the results from their field work, they saw that although there wasn’t a huge impact on the number of rainbow trout, Yellowstone cutthroat trout were disappearing and the presence of pelicans foraging on the river was rapidly increasing. Teuscher and his colleagues watched as pelicans took advantage of the low water levels to stand on rocks and scoop up fish. It didn’t matter if the trout were adults or juveniles; the birds got them either way. There wasn’t anywhere for the trout to hide. In other words: easy pickins.
The outlook for Yellowstone cutthroat trout was alarming. As Teuscher followed the data coming in, he watched as the number of trout plummeted from 4,700 trout in 2001 to less than 20 in 2005.
“I was watching this genetically unique and important population decline,” Teuscher said. “It was happening on my watch. It was part of my responsibility to protect and enhance this population, and I knew we had to do something about it.”
That “something” was an innovative, collaborative relationship between IDFG, the U.S. Fish and Wildlife Service (Service), and a dozen other partners.
Partnerships, Perseverance, and a Precarious Balancing Act
“I can still remember being on the phone with Michelle discussing how to best handle the conflict between American white pelicans and Yellowstone cutthroat trout,” Teuscher said. “These were tough conversations initially.”
Michelle McDowell, the Permits Branch Chief of the Migratory Birds program in the Service’s Pacific Region, was at that time the regional waterbirds biologist. She discussed the Migratory Bird Treaty Act regulations with Dave, and how the Service can only issue depredation permits—permits that allow the removal of birds—under very specific circumstances, including the conservation status of the bird and the nature of the problem that needs to be addressed. In this case, Idaho Fish and Game needed to gather enough data to prove that removal of American white pelicans was necessary in order to protect Yellowstone cutthroat trout.
Both McDowell and Teuscher knew it would be a delicate balance to strike.
“In the 1960s and 1970s, the number of American white pelicans dipped because of the use of pesticides like DDT,” McDowell said. “The number has been increasing since then. The American white pelican is not listed under the Endangered Species Act, but it’s a migratory bird. We have international treaties and regulations in place to make sure their populations are sustained.”
Conversely, the number of Yellowstone cutthroat trout had been declining since the late 1980s. A decade later, IDFG closed all harvest of the trout.
As the data continued to show strong predation impacts, biologists from Idaho Fish and Game and the Service worked together to figure out solutions to protect pelican populations while recovering Yellowstone cutthroat trout. IDFG published predation results, enhanced tagging and monitoring efforts, and carried on the smelly work of sifting through pelican chick regurgitation. The Pacific Flyway Council developed a plan to manage and monitor American white pelicans across the West. Neighboring states pulled together, harnessing the power of many partners, including Tribes, volunteers, National Wildlife Refuges, the National Park Service, the Army Corps of Engineers, universities and their own states’ fish and wildlife staff to do the breeding colony monitoring. The Service’s Sport Fish Restoration program provided financial assistance through grants for the Yellowstone cutthroat trout and pelican management on the Blackfoot River and Reservoir.
In 2006, IDFG began removing pelicans from the Blackfoot River and Reservoir, first as an experiment and then with a larger integrated plan. Teuscher watched closely as the number of Yellowstone cutthroat trout ticked up. It was reassuring to see that as methods to reduce predation were implemented, the trout population responded. In 2013, everyone was amazed to count 1,800 adult spawning fish. Most recently, the numbers are hovering around 1,000 spawning fish.
“We’ve been coordinating for 20 years on how to balance the needs of American white pelicans and Yellowstone cutthroat trout,” Teuscher said. “Anytime you have two species of this level of importance, it adds some challenges.”
In July 2022, IDFG received an award from the American Fisheries Society to recognize their excellence in fisheries management, research, and education. It’s an acknowledgement of everyone involved—scientists, fish and wildlife managers, agencies, and organizations—who are advancing conservation.
“Early on, we recognized that this wouldn’t be easy,” McDowell said. “But we’ve worked hard, and our collaboration is what has made this successful. This award is a recognition of our partnership and finding a way to recover Yellowstone cutthroat trout while conserving American white pelicans. It took a lot of hard work to make it happen.”
There’s still a long journey ahead to recover Yellowstone cutthroat trout so that there’s a sustainable and healthy population. The partnerships will continue. The balancing act between two iconic species will be ongoing.
And the pelican chick regurgitation? That will always be a little bit fishy.
“The recovery is not going to be a beautiful straight line,” Teuscher said. “There’s going to be natural variation. But all signs are pointing up.”