Invasive exotic fish and plants hurt Arkansas fish and wildlife, but they also cost a fortune for the Arkansas Game and Fish Commission to fight.
That means they cost a fortune to the public.
Ben Batten, chief of the Game and Fish Commission's fisheries management division, illustrated that point to the commission Wednesday by highlighting just two campaigns that the agency is waging against invasive plants and fish.
Four species of Asian carp are the commission's most prominent nemeses. We have the silver carp, which is known for jumping out of the water when startled and injuring boaters and anglers. There's also the bighead carp, the grass carp and the black carp. All of these fish have in common high reproductivity and fast growth rates. They have no natural predators, and they can tolerate and even thrive in fast-flowing water.
Exotic carp were introduced starting in the 1960s and 1970s as natural alternatives to chemicals to fight plants and parasites in fish farms, Batten said. Grass carp were introduced because they eat vast amounts of soft vegetation. Black carp eat only snails and mollusks, which helps prevent worms infesting the meat of food fish. That's beneficial, but if they escape into the wild, black carp prey on mussels, which Batten said are the state's most imperiled wild aquatic resources.
Currently, the black carp has been found in only nine states, Batten said, but the silver carp and bighead carp have been found in 27 of the 28 states in the Mississippi River basin.
Resources to fight the spread of Asian carp were slow coming until 2013, the first year financial grants were available outside of the Great Lakes states. In fiscal 2020, $25 million was dedicated to carp control projects in the Mississippi River basin, and $2.4 million was dedicated to the lower Arkansas and lower White River basin.
To date, the Game and Fish Commission's efforts have been limited primarily to containing the spread of Asian carp. The commission's main tools are regulatory, like restricting the transportation of baitfish and regulating possession of certain baitfish.
"We can slow it down," Batten said. "Live fish trade regulations really constrained the number of people that can raise these things and move them around."
Kentucky and Tennessee have successfully enlisted commercial fishermen to target Asian carp, but commercial fishermen in Arkansas have not engaged. Batten said the reason is that Kentucky and Tennessee subsidize Asian carp harvest. Currently, Arkansas does not have access to federal appropriations necessary to fight carp on that scale.
"There is a lot going on, but I'll be battling this the rest of my career," Batten said.
Giant salvinia is a new exotic threat that only recently showed up in Arkansas. Giant salvinia is native to Brazil, and has two large leaves and one small leaf. Jason Olive, assistant chief of fisheries, described it as an ugly plant that has no ornamental value, unlike water hyacinth, another aquatic scourge.
"It's the perfect invader," Olive said. "It reproduces, breaks up and spreads. It eliminates access for hunters and anglers, and it eliminates use by fish and wildlife. It eliminates all the uses that we care about."
Unchecked, giant salvinia can take over a body of water so completely that it looks like dry ground from above. Ducks won't land in it, and since it allows no sunlight into the water, it chokes out the food chain and renders affected portions uninhabitable for fish.
Smith Park Lake in Miller County was the first known infestation. It abuts Sulphur River Wildlife Management Area, and though the lake does not have a boat ramp, it is popular for walk-in duck hunting. The commission assisted in eradicating giant salvinia by draining and drying the lake.
In 2019, giant salvinia was discovered in Lake Columbia, where it has ruined bass habitat, Olive said. It was also discovered in Lake Millwood in 2020. In lakes of that size, the plant is very hard to control because it infiltrates cattail and water willow, where herbicides might not reach it.
"If it has been there long enough, it starts layering," Olive said. "Spraying is a losing proposition ultimately."
Since its discovery in Louisiana, giant salvinia infests 57,000 water acres, almost equal to the surface area of Lake Ouachita.