Hunting for Carp Numbers: Archers Will Round Up Grass Eaters in Effort to Plot Out Hydrilla Plan
By Dan Tierney, The Charlotte Observer, N.C.
Jul. 12–In 2004, biologists began stocking hydrilla-eating grass carp in Lake Norman to help eliminate the presence of the non-native and swiftly spreading plant.
Now, with the help of area archers, biologists could be able to determine how long to continue stocking the fish.
From Aug. 17 to Aug. 19, bowhunters will take to the water in hopes of harvesting at least 30 grass carp. Duke Energy biologists, aided by a specialist from South Carolina, will then age the fish to develop a plan for future stockings.
Other details, such as how many hunters and where they’ll go on the lake, is still unknown, said coordinator Gus Gustafson, who writes a freelance column for Neighbors of Lake Norman.
Phil Kirk, a fisheries biologist for the U.S. Army Corps of Engineers, said typical fish-gathering techniques such as nets and electroshocking don’t work as well as bowfishing.
“(Bowfishing) is by far the most effective way that is out there to collect grass carp,” said Kirk, who has collected data on hydrilla and grass carp for nearly 20 years.
Since discovering about 400 acres of hydrilla in 2004, biologists have stocked in increments around 10,000 grass carp incapable of reproducing. The grass carp then eat the hydrilla, which can produce tubers that lay dormant for up to 10 years before sending new shoots.
The grass carp eat approximately twice their weight daily, before topping out at about 60 pounds, when their eating slows.
Grass carp, many biologists say, help eliminate hydrilla better than other techniques, such as herbicides. The fish are also cheaper, Kirk said.
Hydrilla, which can be transferred from another lake via boats, birds or people, can clog water intakes and damage the ecosystem if left uncontrolled.
Kirk said South Carolina spent about $12 million on herbicides in the 1980s after thousands of acres of water in the Santee Cooper system became infested with hydrilla before the state turned to grass carp, which mostly eliminated the plant. A supplemental stocking of grass carp costs about $1,000.
Because the fish have an average life span of about 10 years, aging a sample of the current population can give biologists an idea of how many more are needed to fight off any dormant hydrilla tubers in the future, Kirk said.
“Unless you’ve got fish foraging on (hydrilla) for a long period of time, it’s going to come back,” he said.
Harvested fish will have a tiny bone removed from their head. The bones produce rings every year, allowing biologists to age fish similarly to how trees are aged.
Duke Energy is obtaining a special permit from the N.C. Wildlife Resources Commission for archers to take more than the currently allowed two per person per day, said Bob Elliott, assistant executive director of the Lake Norman Marine Commission.
If not enough fish are collected, Elliott said, Duke biologists could use Kirk’s analysis from past studies to determine future stocking numbers.
How Bowfishing Works
Most bowfishing is done at night with boats and spotlights. Archers cruise the shallow waters, using bright lights to spot the fish while they feed. Most shots are short-range, as the carp don’t spook as easily at night. It also keeps arrows from skipping off the water.
Bows have a fishing reel attached, with the line connecting to the end of an arrow. Arrow tips are barbed, allowing the arrow to stay attached to the fish while it’s reeled to the boat.
Dan Tierney: 704-987-3670, ext. 33
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