Lake Superior State University
Lake Sturgeon Research in the St. Marys River
by Roger Greil, Aquatic Research Laboratory Manager
Lake Superior State University's Aquatic Research Laboratory (ARL) has been conducting research on lake sturgeon (Acipenser fulvescens) in the St. Mary's River since 2000. Sturgeon are caught on what are called set-lines. Most of the lines are set close to the river channel or along sandy shorelines with sharp drop offs. They are deployed in water depths anywhere from 8 to 50 feet deep. Each set-line is 300 feet long and has 25 hooks. The first hook is set 25 feet from the anchor, and then every 10 feet. Anchors and floats are connected at each end of the lines.
Hooks have been baited with different types of bait - such as strips of pickled squid, fresh squid, smelt, night crawlers, shrimp, chicken gizzards, and strips of lake whitefish, herring, salmon and lake trout. The most productive are whitefish and herring, with lake trout coming in a close third. We now use that bait exclusively.
Lines get checked every other day. If no fish are caught within a week, the lines are moved to a different location in the river. Once a sturgeon is caught, lines are kept at that spot until no more fish are caught for one week.
When a sturgeon is hauled in, different measurements are taken, such as weight (measured in kilograms), total length, fork length, and girth (each measured in centimeters). Then a small cross section of a fin ray is collected from the left pectoral fin (close to the body) for age determination. The tip of the fin is collected for DNA analysis. These samples are sent to the Michigan DNR in Marquette, Michigan. After measurements are taken, the fish is inspected for sea lamprey scars, cuts, marks or any other noticeable features. The sturgeon is then tagged with pit and a floy tags. The pit tag is injected under the third scute, located on the back of the fish, just behind the head. This tag lets a small scanner read an identification number given to the fish. The floy tag is an external tag that attaches near the base of the dorsal fin.
The study's first year, 2000, saw five set-lines placed at the mouth of and in Lake George. This inaugural year was intended to largely work out survey procedures. Two sturgeon were captured over a period of about three weeks.
The second year, 2001, saw up to 10 set-lines placed between Ashmun Bay and Brasser Point. No sturgeon were caught from about May through mid-July. Once we got our set-lines between Brasser Point and Little Lake George, we started catching fish. These lines remained in place until the end of August. We caught 45 sturgeon plus two recaptured sturgeon - one originally tagged in 2000 and the other marked earlier in 2001.
This year 15 set-lines were placed in the lower river, between Palmer's Point, overlapping about where last year's survey left off, and Lake George. If time permits, the ARL aims to work all of Lake George. So far there have been 38 newly captured sturgeon and 8 recaptures in the lower river. All of the recaptures were from 2001.
Ten set-lines were also placed in the upper river this year, starting at Big Point and continuing along the American side of the channel up to Point Iroquois. Only two sturgeon have been captured in that area so far; there have been no recaptures.
Great Lakes Lake Sturgeon Website