Risk Assessment

United States

Riffle community index:

Index areas of macroinvertebrate riffle communities were established in the Brule (Lake Superior) and West Branch of the Whitefish (Lake Michigan) rivers in 1985 and Sturgeon (Lake Huron) River in 1986. Samples have been collected in the spring and fall and before and after lampricide treatments using a standardized traveling kick method. Samples were taken up (control) and downstream (treated) of lamprey barriers in the Brule and Whitefish rivers. Samples were collected from a treated area of the Sturgeon River, and as a control, an untreated portion upstream of a barrier in the Boardman River (Lake Michigan). Field collection of specimens was concluded in the Brule and Whitefish rivers in 1993 and in the Sturgeon/Boardman rivers in 1995. We report the summary tables of laboratory identification of samples collected in the Whitefish (1992-93; Table 28 WARNING: Large file), and Lake sturgeon studies:

Protection of lake sturgeons during sea lamprey management activities is a priority. In 1982, the lake sturgeon was listed in the federal notices of review register as a C2 candidate species and was being considered for threatened or endangered status. On July 19, 1995, the status of lake sturgeons was changed to a species at risk and will not be published as part of a federal register but will be maintained in a national database. Our primary rivers of concern are the Sturgeon and Bad rivers (Lake Superior). We participated as cooperators in the interagency monitoring of the potential impacts of sea lamprey management to lake sturgeons in three studies.

In partnership with the Service Fishery Resources Office in Ashland, Wisconsin, National Biological Service Lake Superior Biological Station, Bad River Band of Lake Superior Chippewa Indians Natural Resources Department, Great Lakes Indian Fish and Wildlife Commission, and Department of Fisheries and Oceans Canada, we participated in a biotelemetry study of lake sturgeons and walleyes in the Bad River between April 17 and June 27. The primary objective was to determine if lake sturgeons and walleyes migrate upstream of two sets of low gradient water falls and the Elmhoist Road Bridge crossing, a potential site for a sea lamprey barrier. Fish were captured in gill and dip nets in the lower river and below the lowermost falls and biotelemetry tags were attached. Few walleyes were captured so white suckers also were tagged. Most of the tagged fishes remained downstream of the Elmhoist Bridge (22 of 23 lake sturgeons, 5 of 5 walleyes, and 8 of 9 white suckers). The Service Office in Ashland had the lead on this work and they have reported to the Commission in a research completion report.

In partnership with Michigan Technological University in Houghton, Michigan, we operated drift nets to monitor the downstream movement of lake sturgeon fry in the Sturgeon River in Baraga County, Michigan between May 25 and June 28. The project was led by Dr. Nancy Auer, Michigan Technological University. Our objective was to determine outmigration and abundance of fry in the upper and middle sections of the river. We operated nets 3 times per week and captured 3 fry (range, 19-24 mm). Even though few fry were caught in 1995, their movement was consistent with similar studies conducted by Dr. Auer in 1992-93. The work continues to support evidence that fry of lake sturgeons migrate out of the upper and middle portions of the Sturgeon River by July 1. In partnership with the Service Fishery Resources Office in Ashland, Wisconsin, Michigan Technological University, Michigan Department of Natural Resources, and the Keweenaw Bay Indian Community Biological Service, we participated in the field capture of juvenile lake sturgeons with trap and gill nets in Keweenaw Bay, Keweenaw Waterway, and Portage Lake of Lake Superior. The objectives of the project were to develop a technique to capture juvenile lake sturgeons and describe their age and size structure. Trap nets were set during June 26-30, July 17-21, August 28-September 1, and September 25-29 and no lake sturgeons were captured. Gillnets were set in Keweenaw Bay during June 27, July 17-21, and September 25-29 and in Keweenaw Waterway on August 29. A total of 8 lake sturgeons (range, 374-793 mm) were captured in gillnets set in Keweenaw Bay. The Service Office in Ashland has a detailed report on the work in the annual report of their station.

Toxicity tests:

In partnership with the Bad River Band of Lake Superior Chippewa Indians Natural Resources Department, we conducted flow-through toxicity tests using 3-trifluoromethyl-4-nitrophenol (TFM) on fresh water mussels (Elliptio complanata), frog tadpoles (Rana clamitans), dragonflies (Stylurus amicola), and larval sea lampreys in the White River (Bad River), Ashland County, Wisconsin, on September 15. The test organisms were exposed to a range of 9 concentrations of TFM (1.4 - 7.0 mg/l) for 12 hours. The regression table LC99.9 (9 hour exposure) for sea lamprey larvae is 2.6 mg/l TFM for the water pH and total alkalinity.

Nontarget organisms in the tests largely were unaffected in concentrations <4.7 mg/l. All mussels and dragonflies survived in all test concentrations. Tadpoles survived at all test concentrations < 3.8 mg/l (1.5 x LC99.9 for sea lampreys is 3.8 mg/l) and 9 of 10 tadpoles survived at 4.7 mg/l (1.8 x LC99.9 for sea lampreys). All sea lampreys larvae died at concentrations> 2.6 mg/l. Treatment levels in the Bad River were <1.6 x LC 99.9 for sea lampreys.

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