Fifth year of river sturgeon study yields insights
Posted: August 12th, 2006
NO ORDINARY FISH TALE -- In this 2001 file photo student workers Adam Nanninga, from Bowling Green, Ohio (left) and Sarah Gobler of Sault Ste. Marie, Mich., haul in a 50-pound sturgeon from the St. Mary’s river for measurement and tagging. Looking on from the right is Lake Superior State University Aquatic Research Lab Manager Roger Greil. LSSU’s sixth season of lake sturgeon research includes tracking the fish with sonic transponders. To view streaming video of a sturgeon run, click here. (LSSU photo by John Shibley)
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MEDIA CONTACTS: Tom Pink, 906-635-2315; John Shibley, 906/635-2314; Ashley Moerke, 906/635-2153
SAULT STE. MARIE, Mich. – They’re unlike any creature in the Great Lakes, and Lake Superior State University is shedding light on the “who, what, where, and why” of prehistoric-looking lake sturgeon in the St. Mary’s River system.
The lumbering fish, some of which live for 100 years, have a physiology related more to sharks than lake trout. And because they are bottom dwellers, taking years to reproduce and mature, lake sturgeon are hit hard by over-fishing and pollution. The St. Mary’s River, which forms a boundary between the US and Canada, has been shaped by both factors. Humans have fished there for more than 2,000 years. For the past 100 years, Sault Ste. Marie has been a hotbed for heavy industry, at various times producing paper, tannery products, steel, and acetylene gas through a process patented by Union Carbide. Eco-friendly steel and paper plants still flourish in Sault, Ontario.
After decades of clean-up and more robust environmental awareness, the question today becomes whether lake sturgeon in their role as ecological benchmarks are making a comeback, thanks to resource management and pollution control. For the past five years, LSSU’s Aquatic Research Laboratory has been trying to find that out.
Since 2000, students and faculty with the lab have captured and tagged more than 90 lake sturgeon. Tentatively, the news looks good. Lab staffers have seen a variety of ages spread over a wide area of the 75-mile (121 km) river network. But something was still missing from five years of work: The ability to track, in real time, the movement of sturgeon throughout the river.
So last year, the Alpena Office of the U.S. Fish and Wildlife Service, Lake Superior State University, the Bay Mills Indian Community, and the Soo Area Sportsmen's Club teamed up on a proposal to the National Fish and Wildlife Foundation to continue and expand the scope of LSSU’s work. The foundation fully funded it, and this year’s catching, tagging and tracking activities that began in May include a collaboration with the Fish and Wildlife Service to track large sturgeon through surgically-implanted sonic tags.
The study’s main goal is to identify critical habitat areas used by lake sturgeon, information that should help managers restore and protect habitat necessary for the recovery of this unique species.
By the end of July, more than 200 set lines have been deployed and lifted, yielding 55 sturgeon. All fish are measured for length, girth, and weight. A small section of the left pectoral fin is removed for aging and genetic tests. Sturgeon captured for the first time have an external “Floy” tag cinched to their dorsal fin. If someone catches the sturgeon, researchers hope this serial-numbered tag gets returned to LSSU.
Teams also inject an internal Passive Integrated Transponder tag just beneath the skin, along the first or third dorsal “scute” just behind the head. The PIT tag’s microchip is readable with a handheld scanner. Coded information gets cross-referenced with a database that matches up when and where the fish was first caught and released, and whether researchers have caught it more than once. The database also tracks specifications collected in the field, such as changes in the fish’s length and weight.
Sturgeon larger than 50 inches (125 cm) get surgically implanted with sonic telemetry tags. The transponders emit sound pulses at certain intervals, which let earphone-equipped researchers track an implanted fish as it moves throughout the river.
Batteries in the transponders should let researches track the fish for up to four years. So far, 11 sturgeon caught this season have been large enough for sonic tagging. The year’s largest sturgeon was more than 57 inches (145 cm) long and had a girth of 25 inches (64 cm). The 54-pound (25 kg) fish was confirmed to be a female when its sonic tag was implanted. Hopefully, she will lead researchers to her spawning habitat within the St. Mary’s in subsequent years.
Tagged sturgeon have largely remained in a 15-mile (24-km) tract of the St. Mary’s between Michigan’s Sugar Island and Canada. However, one fish traveled 10 miles downstream through Lake George, actually a widening in the channel, to reach a section that borders Michigan’s East Neebish Island and Ontario.
Researchers have also noted movement in other fish that exceeded five miles (8 km) over a period of three days in June.
This season’s catching and tagging wraps up in early September. Funds for sonic tracking continue through 2007.
LSSU’s Aquatic Research Lab is still looking for boat owners willing to transport researchers on tracking expeditions. For more information on the project, or to volunteer, contact the lab at 906-635-1949.
To view streaming video of a sturgeon run, click here.