To find out what the catfish were eating, the researchers collected 576 catfish over two years using electrofishing and hoop net capture methods, as well as the fish lift at Conowingo Dam, of which 241 were caught. had recoverable stomach contents. The researchers extracted DNA from these contents and used a molecular genetics technique known as DNA barcoding to identify the prey’s tissues. The researchers performed genetic sequencing of selected stomach contents at the Penn State Huck Institute for Life Sciences’ Genomics Core Facility.
In total, researchers identified 47 different prey species. Thirty-four of the detected species were infrequent, occurring in less than 2% of sampled fish. The most common were the rusty crayfish, the merged mudtom (a type of catfish that is typically 2 to 3 inches long and considered a protected species), and the shiner, a small silvery fish. Although the frequency of prey species varies depending on the length of the flathead catfish, rust crabs were found in the stomachs of nearly half of the fish sampled in the study.
Other prey species identified include blueback herring, gizzard shad, northern hog sucker, shorthead redhorse, goldfish, river mab, bluntnose minnow, long-tailed dace, white catfish, brown bullhead, channel catfish, flathead catfish, Included were striped killifish, rock bass, and green sunfish. , bluegill, smallmouth bass, white crappie, black crappie, white perch, greenside darter, yellow shield darter, and walleye.
Not surprisingly, as flathead catfish grow in size, they tend to eat larger prey, the researchers said. Generally, flatheads over 24 inches in length feed primarily on fish species, while fish under 24 inches generally feed on a mixture of invertebrates and fish species.
Flathead catfish in the Susquehanna River basin prey on a variety of prey species, including recreationally important species such as smallmouth bass, rock bass, channel catfish, and walleye, as well as conservationally important species such as blueback herring and marge mud tom. Knowing what is going on will help the fishing industry. According to Schall, these are the managers who oversee the river.
“Identifying the prey species consumed by this invasive predator is one of the first steps in elucidating the potential community-level impacts of this actively expanding aquatic invasive species.” she stated. “That knowledge is essential for determining potential management solutions against emerging intruders.”
