The Asian carp is a skittish fish, averaging about two feet long and 10 pounds apiece. When startled by something, say a boat’s motor, it’s prone to jump up to 10 feet in the air. So when Blake Ruebush, Levi Solomon, and Chase Holtman, an ecology team with the Illinois Natural History Survey, head out on an early October carp-hunting mission, they do so with caution, and armor.
Ruebush’s steering console has been modified with a carp-proof Plexiglas windshield and a side wall of mesh netting to guard the throttle and steering wheel from aerial impact. The team considered wearing helmets but dismissed the idea as too dorky. Instead, despite the humidity, Ruebush and Solomon wear waders to repel the slime. Holtman, a burly-looking guy, has gone the other way, opting for a T-shirt, shorts, and Crocs. “I’ll shower afterwards,” he says. “People look at you funny when you reek of blood and fish.”
As they head out from Havana, Ill., and up a side channel of the lower Illinois River, the water starts to churn with agitated fish, and the boat’s hull thumps from underwater collisions. Then the fish start flying—dozens of them, rising like a storm cloud. One ricochets off the boat’s guardrail; another leaps in from behind the boat, getting tangled in the motor’s steering cords. The air is so thick with fish that some bash together mid-flight, showering everyone with a snot-like splatter.
The fish come in at close to 30 miles per hour. That’s enough to cause bruises and broken noses—even concussions have been recorded—but Ruebush and his crew seem unworried. “This is Ground Zero for Asian carp,” Ruebush says, steering forward as his buddies stand at the front of the boat. They won’t have to endure the barrage much longer, though. They’re about to electrocute all the fish.
Solomon and Holtman lower two 10-foot booms attached to a generator capable of producing 5,000 watts. Ruebush starts the generator’s engine. It’s like a giant underwater Taser. As Ruebush motors ahead, fish that swim into the field will be stunned, then scooped off the surface by Solomon and Holtman with dip nets and dumped in a tub in the center of the boat, where they are identified, measured, weighed, and counted.
As the generator goes hot, they jump even higher. A fish hurdles the guardrail, skittering to a stop at Ruebush’s feet. “Hey! There’s a volunteer. We count those, too,” he adds, chuckling. Within a minute the water quiets and unconscious fish begin rising to the surface.
The electrocution, one of four that will occur in the area today, will last 15 minutes and cover about 200 yards of shoreline. INHS runs thousands of these “fish community assessment” collections a year—a mix of shock fishing and other techniques such as netting—to track changes occurring in the river. The group is looking for two different species of Asian carp. The jumpers surrounding the boat are Asian silver carp. The Asian bighead swims closer to the bottom of the river and is harder to zap. Both are filter feeders and thrive on plankton, a flotsam of algae and other microorganisms.
In the 1970s, fish farmers in mostly Southern states began importing Asian carp from China to help clean their commercial ponds. Some escaped in floods, making their way into the Missouri River, the Mississippi River, and the Illinois and Ohio River basins. They breed fast, grow fast, and eat piggishly. Females can spawn up to three times a year, releasing millions of eggs per drop. Young fish easily eat their weight in food daily, while adults can consume up to 20 percent of their body weight. That yields silver carp as big as 50 pounds and bigheads up to 100 pounds. After their first few months, the fish outgrow their natural predators in the river system. And they pick it clean.
Thanks to the interconnectedness of America’s waterways, Asian carp now infest more than 23 states, mostly in the Midwest. But they are not yet in the Great Lakes, home to a $7 billion fishing and $9 billion boating industry, according to the Great Lakes Boating Federation. Havana and the 210 river miles north to Chicago represent the last stand in the battle against the carp.
by Ben Paynter, Bloomberg Businessweek | Read more:
Image: Minnesota Public Radio
