Skip to main content

Grad works to reverse Southwest's native fish decline

illustration of fish
July 29, 2010

When Jason Schooley graduated from Arizona State’s School of Life Sciences in May 2010, he left behind tools to make the Southwest a better place for its native fishes – one pond at a time.

Schooley came to ASU to study the denizens of the desert’s inland waterways; native fish with names that tell tales: razorback sucker, bonytail, Moapa dace, sardinita bonita, flannelmouth sucker, and Apache trout.

“At one time razorbacks were so plentiful that settlers pitchforked them from canals to use in the fields as fertilizer,” said ASU professor Thomas Dowling, Schooley’s thesis adviser. “Of the 36 species unique to this region, more than half are listed as endangered or threatened.”

The razorback sucker is one of these. Named for its prominent keel, which makes it resemble a humpbacked trout, this native to the Southwest can live 40 or more years and grow to 60 cm (more than two feet) on a diet of planktonic and benthic algae and invertebrates.

Recovery efforts have been made, Schooley said, but razorback numbers remain low despite efforts at federal and state hatcheries to raise and release millions of razorback into the wild.

Besides historic overfishing, human activities and their byproducts, such as pollution, pumping of ground water and damming of waterways have also token their toll. Even if these obstacles could be overcome, introduction of non-native sport fish species, such as bass, catfish, bluegill and red shiners, their predation on native fish young or competition for food sources also squelch native fish recovery efforts.

Native fish are under siege and in steep decline, Schooley said: “I had to ask myself, ‘What can I do to contribute to the understanding of this phenomenon?’ Furthermore, are there any simple steps we can take that can make a big difference in recovery?”

His questions brought him to regional fish expert Paul Marsh, a now-retired faculty research associate from ASU’s School of Life Sciences and director of the Native Fish Laboratory in Tempe, Ariz. Schooley’s meetings with Marsh inspired his master’s degree studies with Dowling. His inquiries also took him deep into the history of the region and its inland fishes, with additional guidance from Anthony Gill, curator of ASU’s animal collections and an international expert in fish taxonomy.

Ultimately, Schooley found himself reviewing the literature of the late Wendell Lee Minckley, the Southwest’s biggest fish-in-the-native-fish-studies pond. Minckley, an ASU emeritus professor, ardent conservationist and internationally respected authority on native fish, published more than 200 journal articles and books about the Southwest’s finned natural resources. Three of the most prominent of which were the landmark “Fishes of Arizona” (1973); “Freshwater Fish of Mexico,” coauthored with Robert Rush Miller and Steve Mark Norris in 2006; and, most recently, “Inland Fishes of the Greater Southwest: Chronicle of a Vanishing Biota,” (co-authored with Marsh) and posthumously published by University of Arizona Press in 2009.

“Arizonans love their parks and wildlife,” Marsh said. “But there’s a lot we still don’t know that can help us protect native fish from extinction. It’s important to have research and research-based tools available so that policy makers can make the best management decisions.”

“That said,” Marsh added, “many of the tools already are available and have demonstrated effectiveness, but conflicts, especially with sport fishing interests, often compromise the progress of native fish conservation.”

Conservation entities like Marsh’s Native Fish Laboratory, and non-game branches of federal and state wildlife authorities, have worked to advance research, develop and implement legal protections, remove pest species and install physical barriers, develop effective hatcheries and stocking programs, and use natural barriers to isolate native fish from predators. Fossil Creek is one site in Arizona where native fish, like the headwater chub first described by Minckley, have found sanctuary. One of the last free flowing creeks in the state, natural flows were re-established here with removal of a diversion dam in 2005 and removal of non-native fishes. The creek is now a refuge for native fish above a new barrier that protects them from non-natives. 

With support from Marsh and Dowling, funding from the U.S. Bureau of Reclamation, cooperation from federal and state resources management agencies, Marsh’s Native Fish Lab, and members of ASU’s native fish working group, Schooley set out to study what was limiting survival of native fish released from hatcheries into the lower Colorado River.

Schooley’s findings offer new insights to help resources management agencies devise more effective conservation and recovery plans for natives.

“What these fish do in the first 100 days after their release from hatcheries turns out to be crucial to their long-term survival," Schooley said. "We found, for example, that release of hatchery fish in winter months subjects them to higher rates of predation by birds because the river is a migratory flyway in December and January.”

Also, Schooley’s research suggests that razorbacks from hatcheries school at the surface – an unnatural behavioral habit developed because of feeding regimes in hatcheries where they were raised. He hypothesizes that these behaviors made them vulnerable to predation by birds.

“Of the 3,200 fish experimentally tagged and released, we found that upon recapture more than 24 percent had wounds consistent with predation by birds like herons, cormorants, pelicans and osprey. And those are just the ones that survived," he said.

Schooley said that more research is necessary to fully understand and counter the impacts of humans and wildlife on native fish.

“Native fish sanctuaries are a reality. But we need separate habitats that are not dual use – imperiled species cannot coexist with the species that harm them," he said. "Native fish recovery requires complete and permanent insulation from the threats limiting their survival ... a difficult and expensive endeavor.”
Public education is also critical, Marsh said. To help spawn new understanding about Arizona’s underwater natural resources, his organization developed the Sharing Tail program. An environmental outreach program, the project makes it fun for kindergarteners to learn about native fish and their habitats.

Managers of Southwestern aquatic resources now struggle with the economic and budget woes that face the nation at large. For example, the Arizona Republic reports that funding is down to Arizona’s park systems. The Department of Water’s Resources budget and workforce has also been halved, which can affect groundwater management, resource planning and sustainable water supplies. However, ASU students, faculty and alumni like Marsh, Dowling and Schooley (who is now with the Oklahoma Department of Wildlife Conservation in Tulsa, Okla.), and agencies like the U.S. Fish and Wildlife Service and others, are working to protect Arizona’s and the nation’s living legacy, offering guidance to preserve native fishes’ finned future.