Native discovery could save important fish

The scientific discovery of an ancient stress hormone by a tribal member could lead to the survival of the most ancient of the native fish in the Pacific Northwest, the Pacific lamprey, an eel like fish that evolved more than 500 million years ago.

David Close, Ph.D. is a Cayuse and a member of the Confederated Tribes of Umatilla in Northeastern Oregon, a Columbia River treaty fishing tribe that’s been at the forefront in calling the Pacific lamprey’s restoration.

Close, a professor at the University of British Columbia discovered the corticosteroid hormone, which is important for monitoring environmental impacts that stress the lamprey like when they’re going down river in barges or trying to negotiate fish ladders designed for salmon.

Like salmon, the Pacific lamprey is born in freshwater and travels to the ocean for its adult life, then returns to the upper reaches of rivers where it forgoes food for a year before spawning. Before construction of the dams, tribal peoples fished for the once abundant lamprey in the falls along the Columbia and its tributaries. There are only an estimated 11,000 left in the Columbia River.

The lamprey is a culturally important subsistence and medicinal fish for the Columbia River tribes, who want it targeted for conservation in the way that endangered salmon populations are in Washington, Oregon and California rivers.

Close began his career in the Umatilla fisheries program, where he published oral histories of tribal elders who helped him to understand the biology of the lamprey and who charted its decline starting in the 1970s.

He used the sea lamprey, the Pacific lamprey’s cousin very abundant in the Great Lakes as a model. “We needed to get a lot of blood to isolate the steroids, and we couldn’t use the Pacific lamprey because we didn’t want to kill this delicate population,” Close said. The findings are also important for the control of the sea lamprey, an exotic fish blamed for decimating the Great Lake’s fish population.

His findings have a practical application in efforts to save the Pacific lamprey in the Columbia River, where the clinical monitoring of stress hormones in salmon has aided conservation efforts for decades. And they’ve also aroused the interest of the international scientific community.

The implications are significant to the study of the evolution of stress hormones and their receptors. The lamprey as one of the oldest living vertebrates has a single corticosteroid and a single receptor for that hormone, while modern vertebrates including humans have two corticosteroids and receptors that function to balance ions and the stress response.

“Through evolution, eventually these ancestral functions for responding to stress and ion balance diverged after a genome duplication event that produced two corticosteroid receptors,” Close said. “That’s how we think complexity in organisms has increased … when these functions diverged, it allowed vertebrates to exploit more diverse habitats. It is about the co-evolution of steroids and receptors and eventual divergence of ancestral functions.”

The findings, published in the Proceedings of National Academy of Sciences Early Edition also point to the importance of indigenous knowledge to science. Close considers traditional knowledge just as important as western science to the management of tribal resources. He directs the University of British Columbia’s Aboriginal Fisheries Research Unit that trains indigenous students to conduct cutting-edge research of importance to indigenous communities in North America.

“Most of the time, we have been hiring people to come in and do this science for us,” he said. They can miss important insights into natural processes that are known to our cultures, because of their cultural biases.”

Terri Hansen is a freelance writer who covers indigenous people and the environment. She writes at Mother Earth Journal.

Lamprey image courtesy Flickr stream of US Fish and Wildlife Service Pacific Region.