How Maryland DNR Is Working To Manage The Invasive Blue Catfish

CALIFORNIA, Md. — The BayNet previously reported on how invasive blue catfish have spread through Maryland’s waterways and why they pose a growing threat to the Chesapeake Bay. In this follow-up, state officials detail how the Maryland Department of Natural Resources (DNR) is shifting from eradication to long-term management to reduce ecological damage.

Branson Williams, a freshwater biologist and invasive fishes program manager with DNR, oversees the state’s efforts to research and manage invasive fish species. The program, which officially began in fall 2023, focuses primarily on blue catfish, northern snakehead and flathead catfish.

“Once an invasive species becomes established, it’s really difficult to get rid of them,” Williams said. “The goal now is to reduce abundance and biomass in a way that minimizes ecological impacts.”

Promoting Harvest As A Management Tool

One of the most effective tools DNR uses to manage blue catfish populations is encouraging harvest for consumption. Blue catfish are considered good table fare, and state officials see market demand as a way to remove large numbers of fish from the ecosystem.

“We were lucky that blue catfish taste good,” Williams said. “They’re a mild, white-fleshed fish, and there’s definitely a market for them.”

DNR works closely with seafood processors, harvesters and marketing partners to promote blue catfish as a food source. Supporting that market, Williams said, helps reduce overall biomass while also benefiting local watermen.

Commercial harvest numbers illustrate the scale of removal efforts. In 2024, approximately 4.4 million blue catfish were harvested statewide, with about 3.1 million coming from the Potomac River alone.

Research And Monitoring Efforts

In addition to harvest-based management, DNR is expanding its research and monitoring programs to better understand blue catfish populations and their impacts.

Last year, the agency conducted its first official blue catfish survey through a pilot program that partnered with commercial harvesters. The effort used electrofishing and commercial watermen with chase boats to collect biological data while simultaneously supporting local fishing operations.

Electrofishing temporarily stuns fish using low electrical currents without killing them, allowing researchers to safely sample populations. Blue catfish are particularly sensitive to long-wavelength electrical currents, making the technique effective for data collection.

“It’s a lot of field work for a small team,” Williams said, “but it gives us critical information we can use to guide management decisions.”

DNR also collaborates with regional partners and research organizations to track invasive species trends and prevent new introductions.

What The Public Can Do

Williams emphasized that public participation plays an important role in managing invasive species.

Residents can help by purchasing blue catfish, targeting them through recreational fishing and reporting sightings in new locations. DNR encourages the public to use the Maryland Invasive Species Tracker, a web-based reporting tool, to document invasive species occurrences.

“If you see blue catfish in reservoirs or places where they haven’t been documented before, let us know,” Williams said.

Consumption advisories do exist for fish caught in Maryland waters, typically related to long-term exposure to contaminants such as mercury or PCBs. DNR advises residents to follow state guidance, particularly for vulnerable populations.

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