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Sauger Science: A Native Fish In Trouble

by Kris Kuhn

Researcher with a Sauger ready for transmitter

The second of three research projects undertaken to better understand the life cycle and habitat requirements of the genetically-pure Wind River Sauger has recently come to an end (see the Winter 2004 and Summer/Fall 2004 issue of Wind River Waters for more details). In mid-July, University of Wyoming Zoology graduate student Kris Kuhn completed a year-long research project examining the movement patterns and habitat use of Sauger in the Wind River drainage.

Sauger (Sander canadensis – a member of the perch family) are native to the Wind River drainage and are an important food for the Wind River Tribes. Sauger numbers are declining throughout the U.S., and the Wind River is home to the last genetically pure population in Wyoming, because Sauger interbreed with introduced Walleye. Despite its importance, little is known about what habitat the Sauger use during winter and spring spawning In light of the recent population declines across much of their native distribution in North America, information gained through this research will be critical to protect this genetically pure sauger population into the future.

Under the direction of Professor Wayne Hubert, leader of the Wyoming Cooperative Fish and Wildlife Research Unit, Kuhn began field work in the summer of 2004. This project was a cooperative effort involving the Wyoming Game and Fish Department, U.S. Fish and Wildlife Service, Shoshone and Arapaho tribes, the University of Wyoming, and numerous private landowners in the area.

Kuhn surveyed and mapped approximately 60 miles of river habitat on the Little Wind and Popo Agie rivers. Habitat was surveyed to quantify winter and spawning habitat. Kuhn found that deep, slow, cloudy pools—the preferred habitat of sauger—are abundant throughout the drainage. Suitable spawning habitat, however—river bottoms characterized by clean gravel, cobble, or boulder— was sparse and scattered through the drainage.

Kuhn surgically implanted radio-transmitters in 54 adult sauger in the lower reaches of the Little Wind and Popo Agie rivers and tracked their movements and habitat choices for nearly a year. In general, sauger in the Wind River drainage remain stationary during fall and winter in deep pools. Most tagged sauger occupied a limited range usually less than 100 yards from where they were tagged that fall. Movement increased slightly towards the end of November when water temperatures dropped to near freezing and tagged sauger sought out the deepest and slowest pools in the immediate area to spend the winter.

Sauger movements increased drastically during the spring and summer with some tagged sauger traveling as far as 18 miles from their winter location. This increased mobility is believed to be associated with movement to and away from a primary spawning site. The majority of tagged Sauger converged in one small section of the river for spring spawning. The sauger dispersed after spawning. Displaying a strong homing instinct, the fish traveled back to the exact areas where they had spent the fall.

Recent research estimates the Sauger population in the Wind River drainage at only 4,300 fish. This small number, coupled with a small, specific spawning site make the sauger vulnerable to extinction. Looming coalbed methane development near the spawning ground seriously endangers the Sauger. The U.S. Fish and Wildlife recently registered its concern with the EPA:

“Sauger is a species of concern and is a potentially T&E listable species because of the declines observed and threats to its habitat. The principal spawning site has been identified in a one to two mile section below the confluence of the Little Wind River and Beaver Creek The success of spawning is critical to population sustainability. Changes in water quality will likely be detrimental to spawning success...CBM development is currently occurring on private land along Beaver Creek and methods of disposal of CBM water is not known at this time…discharge from Riverton Dome will likely reach the Little Wind River. The potentially harmful effects on Sauger are unknown and should be explored.”