The invasive species has spent the past five decades working its way into almost every local waterway and threatens to upend the ecosystem. Virginia officials are weighing a new way to cut down on the population by letting anglers go after them. The Virginia Board of Wildlife Resources will soon decide whether to remove the recreational catch limit on blue catfish. The change would apply to the Rappahannock and York rivers, as well as portions of the James below the freshwater-saltwater transition zone.
Blue catfish, which are native to the Gulf coast and central U.S., were originally brought to Virginia by the same agency now trying to reduce the population. The Department of Wildlife Resources introduced the species into the James and Rappahannock rivers in 1974, followed by additional stockings in the York. The goal at the time was to create a “recreational trophy fishery” to support anglers as the striped bass population was crashing coastwide, DWR states on its website.
Once established, blue catfish exploded in Virginia, preying on native critters such as blue crabs. “Things went a little haywire,” said Chris Moore, Virginia executive director with the nonprofit Chesapeake Bay Foundation. “We're in a situation now where they really don't have a lot of predators except for themselves, and they have just expanded exponentially.” Virginia Commonwealth University estimated that blue catfish now account for up to 75% of the total weight of fish in some local rivers. “Having a single species representing that much biomass is not a great thing,” Moore said.
Flathead catfish (Pylodictis olivaris) may look like they are perpetually smiling, but these five foot-long fish are no laughing matter in regions where they do not belong. The opportunistic predators are now one of the top predators in Pennsylvania’s Susquehanna River, creating a major threat to the local food web. Without any natural predators to keep them in check, these enormous fish can alter a river system in only a matter of years.
Flathead catfish are native to several parts of the United States, including the Missouri, Mississippi, Ohio, and Rio Grande river basins. They are most recognizable by their broad flat head (as the name suggests) and lower jaw. It also sports a distinctive tail fin outline that is square or slightly notched. They are also really big. They can grow up to 60 inches long and weigh roughly 30 pounds on average. Some have even been known to tip the scales at over 100 pounds. According to Pennsylvania Sea Grant, their coloration can vary, but most adults have an olive-colored back and sides with dark brown to yellow-brown mottling.
One thing that separates them from other catfish species is their diet. They are considered obligate carnivores and primarily prey on live fish.
While flathead catfish are native to western Pennsylvania, the first report of the species in the Delaware River basin further east was from Blue Marsh Reservoir and in the Susquehanna during the 1990s. Since then, they have continued to spread throughout regions of the Delaware, Schuylkill, and Susquehanna rivers.
“Flatheads grow fast in this river system, attain large body sizes and can eat a variety of prey,” Olivia Hodgson, a master’s student at Penn State University, said in a statement. “Because adult flatheads have few natural predators, flathead catfish can exert strong control over the ecosystem.”
Hodgson is the co-author of a study recently published in the journal Ecology, which found that the flathead catfish are now considered apex predators. They are higher on the food web than resident top predators like the channel catfish and smallmouth bass. Since the channel catfish now have a lower position in areas where the flathead catfish are present, they have to eat lower on the food web. In areas with flathead catfish all species showed broader and overlapping diets, according to the study.
“This suggests that resident species are changing what they eat to avoid competing with or being eaten by the invader,” Hodgson said.
Put a bounty on both of them.
The Wombat has Rule 5 Sunday: Fall Colors up and garnering clicks at The Other McCain.
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