MONITORED FISH LOCATED, STUDIED, (BY HOVERCRAFT)
(Views from a non-hovercrafter) Article from local newspaper by Joe Wilkinson Reprinted here with permission.
IOWA CITY - With six or more inches of crystal-clear ice beneath me, I really didn't need to worry. Still, as the giant sheet readjusted itself, the cracks and groans were a little unnerving. So was the occasional vibration. But if you're going to keep track of where the fish go in the winter, you deal with ice.
Ahead of me, Maury Anderson walked with his radio telemetry receiver. The steady 'blip, blip, blip' told him that the bluegill we sought was just a few feet awawy. Research workers from the Department of Natural Resources fisheries station at Bellevue (IA) fitted 31 bluegills and crappies with small radio transmitters this past fall. Through the winter, they dial up individual frequencies, to locate their fish.
After pinning down the spot, Anderson cut through the ice and broke out his monitoring equipment, checking water depth, temperature and dissolved oxygen level in this backwater lake, on the Mississippi River below Dubuque (IA).
"We are trying to locate these fish and find their wintering areas," explained Anderson. "This bluegill was about 30 yards from shore in 4 feet of 36-37 degree water. That's a nice warm winter temperature and the dissolved oxygen shows up at 33 parts per million. That's extremely good."
In short, it had the look of a valuable wintering area for Mississippi River panfish. That could make it a prime candidate for extensive renovation - dredging - down the road.
"Winter areas are important for panfish," stressed Anderson. "With the sedimentation in the river, what used to be 10-12, 15feet deep is now 3, 4 or 5 feet deep. You can count on one hand how many wintering areas there are."
In bitter cold winters, the annual sediment build from the bottom and ice thickening from the top, even those prime areas are squeezed in an environmental vice. That was all too apparent last winter, when fisheries workers had to drill through a foot of backwater ice to find just two feet of water, supporting winter panfish. The oxygen level was often below 2 parts per million causing sever stress on the fish.
This particular bluegill had moved to Stone Lake, below Massey Station, from another spot, about six miles outh. Researchers show another 10 to 12 tagged fish still there. They'll be monitored once or twice a week through the winter.
The price tag on most Mississippi River dredging projects heads upward from a million dollars. That means biologists have to be sure of their recommendation before asking the Corps of Engineers and their own agencies to commit to the project. When complete, though, the renovated backwaaters offer new life to river species. Fish must survive the winter to flourish in the warm weather months. And they can't do it if their pre-lock and dam habitat fills with sediment. Mitigation money from the Corps pays for the projects on the Upper Mississippi River, but demand outpaces supply. Only five or six projects are funded each year. Even when a certain area receives the nod, it could be a decade before dredging gets underway.
While panfish receive the direct benefit, the entire River ecosystem gets a breath of life, from themajor renovation push. Larger gamefish feed on the panfish. So do a variety of wildlife species. Humans, too, see better fishing for all species, not just during ice fishing season. A major winter kill of backwater fish has a ripple effect up and down the Big River.
**How do you get to a remote backwater lake for research work? A 15-foot hovercraft does the job for fisheries workers on the Mississippi River. Held aloft by air kicked out of a 10-horsepower engine, the tiny craft floats over ice, water, gravel and snow with ease. An 18-horse engine and huge air blade propel it across the icy surface. Other than the engine, must of the boat is lightweight fiberglass and styrofoam.
Controlling the lighter-than-air craft takes practice. With only air between the boat and the ice, the only 'brake' is cutting power well before you want to stop or reversing direction and gunning the motor to have the blades blow you to an almost-out-of-control stop. Likewise, turns must begin well before you actually need to change direction. Anderson and I had short spurts of maybe 30-miles an hour or higher this week. Top speed is perhaps double that, but as another researcher pointed out, "when it takes a half mile to stop, you're not that interested in the top end."
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