Invasive fish, Part 2 — the managing

I took this flathead catfish night fishing with Allen Peterson below Dam #5 on the Potomac River. This is a small to medium-sized specimen.
I took this flathead catfish night fishing with Allen Peterson below Dam #5 on the Potomac River. This is a small to medium-sized specimen. (Bill May photo)

Addressing invasive species issues requires dealing with two groups resistant to management — fish and people, so sound, scientific principles must be applied but psychology and human relations principles may be even more important.

This column attempts to summarize hundreds of pages of articles and studies on blue catfish, flathead catfish and northern snakeheads. To repeat from Part 1, they are considered invasive to the greater Chesapeake Bay and its tributaries since they are “non-native species that cause harm to the economy, to the environment or human health” or “reproduce and expand beyond their initial areas of introduction.”


The catfish species are prolific breeders with few natural predators, long lived, fast growing, voracious and potentially threatening changing populations and distributions of native species. Snakeheads are not as long lived and have many predators. The threatened native species may include striped bass (and Maryland is the most important nursery of the Atlantic stock), largemouth and smallmouth bass, white and yellow perch, channel catfish and other catfish, shad and even blue crabs.

So, the Maryland Department of Natural Resources is one of nearly a dozen state, interstate and federal agencies and research organizations taking action to “examine potential measures to reduce densities and limit range expansion and evaluate possible negative ecological impact.” Anglers and commercial fishing interests will also play roles in this.


Since invasive catfish may be the major problem in the mid-Atlantic area I’ll summarize the seven recommendations of “The invasive Catfish Task Force” with most recommendations also applicable to the national “Northern Snakehead Working Group:”

Design and implement targeted fishery-independent removal in places of significant ecological value;

Incentivize and accelerate large-scale commercial fisheries;

Incentivize increase harvest by small boat operation and explore commercial electrofishing;


Establish monitoring and tracking programs;

Study the effectiveness of existing barriers versus removal of some barriers;

Do cross-jurisdictional reviews of current fishing policies and regulations and evaluate effectiveness on persistence and expansion of invasives;

Provide accessible and consistent information on invasives to anglers and the general public.

Allen Peterson launches his custom catfish boat on the Potomac River. This rig demonstrates the growing popularity of catfishing.
Allen Peterson launches his custom catfish boat on the Potomac River. This rig demonstrates the growing popularity of catfishing. (Bill May photo)

All but the second recommendation also apply to snakeheads (which could possibly redistribute to all contiguous states and some Canadian provinces), and recommendations 2, 3, 4, 6 and 7 all involve fishermen.

Since the invasives cannot be eliminated from most current locations with current technologies and management practices, controlling populations and distributions is the major strategy.

The latest figure I could find on the value of the commercial harvest of blue catfish was $1.7 million (NOAA). While some envision a happy solution of increased commercial and sport harvest, things aren’t quite that simple.

On the plus side blue catfish and flatheads are good table fare and snakeheads even more tasty, and, at least in Maryland, there are no limits to harvest or closed seasons. The Wide Net project is working with watermen, processors and distributors to provide blue catfish filets to restaurants, distributors and food markets such as Whole Foods. For every pound of catfish sold, Wide Net donates one meal portion to food banks.

Can the blue cat fishery expand? The investment in new equipment to switch to this fishing from fishing for other species is not great. Some commercial fishermen are adding catfish to their targeted species, and some are even switching from crabbing to catfish.

But there are several limits to the blue cat fishery. One is the bioaccumulating of toxins for fish of any species that feeds on other fish. A maximum size catch of 30 inches (8 to 12 pounds) for a blue catfish has been suggested, but there are numerous factors that can affect safety and recommendations for consumption advisories — another area for more study. A second is that catfish fillets lack the cachet of such species as striped bass or flounder. This call for more public information and marketing, since many find wild blue catfish far superior in taste to farm raised catfish. A third is the recent movement of catfish inspection from the Food and Drug Administration to the Department of Agriculture, which may impose serious additional burdens on fish processors and limit additional catfish processors. This may call for legislative action.

How much of a commercial fishery exist for flathead catfish is unknown. Snakeheads are being sold by commercial fishermen and bowhunter harvesters directly to restaurants and some wholesale distributors, and most of the above concerns are not pertinent.

Sport fishermen are likely not major factors in harvest of all three major species. Fishermen like to catch, and re-catch, big fish. The CPR (Catch, Photograph and Release) ethos of Catfish Nation is likely prevalent for all these invasives.

Some major questions for studies are:

How do native species and invasives interact in certain environments?

How do the invasives species redistribute? (Some appears to be the result of illegal stocking, but much of it is due to species adaptability.)

And there are a plethora of unknowns to any actions taken, including:

What will be the bycatch of any harvesting method?

How will the targeted invasives react to increased harvesting, e.g., by greater proliferation and relocation?

Will efforts to market invasives and the growing popularity of trophy and tournament fishing lead to commercial and sport fishing efforts to illegally stock fish in other waters where the impact of the invasives could be even more destructive?

The Maryland DNR is taking the approach of encouraging commercial and sport fishing harvesting and public information campaigns.

It may be decades before some kind of equilibrium is established in mid-Atlantic and national waters.

In the meantime, it is critical that anglers and the general public cooperate with official actions. Illegal stocking of any of these invasives could produce devastating results.

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