In the Chesapeake Bay, there are several different species of catfish, some of which are native and some of which are introduced species that have become invasive.
The first thing to know is what exactly is an invasive species. This term often gets used but not always correctly. An invasive species needs to be two things; it needs to be non-native to a particular area and it needs to cause harm in that area, either to human health, economic systems, or ecosystems.
Basically, this means that a particular organism was introduced to an area where it was not previously found and it is negatively affecting that area, either by outcompeting native species, interrupting agricultural species, or being vectors for the spread of disease in humans.
Some species are introduced and therefore non-native, but don’t negatively affect their new ecosystem, meaning that they aren’t technically invasive. For these organisms, we typically just refer to them as introduced or nonnative. All of this information lets us distinguish between native species, nonnative species, and invasive species and understand that invasive species are what we want to focus removal efforts on.
In the case of catfish in the Chesapeake Bay, we have several native species, a nonnative species, and several species that are considered invasive. Native species include the brown bullhead, the yellow bullhead, and the white catfish. The single nonnative (but not considered invasive) species is the channel catfish. The invasive species are the flathead catfish and the blue catfish.
Our resident catfish, Felix, at Phillips Wharf. The unforked tail suggests this is a bullhead catfish of some kind and therefore a native species.
The channel catfish, while introduced to the Chesapeake Bay from Canada and the midwest, aren’t considered invasive because they don’t appear to negatively affect other wildlife. And though they aren’t considered invasive now, that may change as we learn more about the impacts that this species has on native Chesapeake Bay animals.
In the case of blue catfish, they are an invasive species of concern because they spread throughout the Bay due to their ability to tolerate a wide range of salinity. Back when blue catfish were first introduced to the Bay, the goal was to support a recreational fishery in freshwater tributaries, but the catfish were able to migrate out of those areas and spread throughout the Bay. In addition to their ability to spread, they produce large numbers of offspring when they spawn, and they eat a variety of prey including blue crabs, and it is believed that they are negatively affecting populations of Striped Bass, American Shad, and Menhaden, which are all economically important fish species.
Just like blue catfish, flathead catfish were also introduced to create a recreational fishery, but they can grow up to 100 pounds and live for up to 28 years, giving them the opportunity to eat a lot of other fish and crustaceans and to make many thousands of baby catfish.
However, some argue that these so called invasive catfish species are now established in the Bay and also add value as a popular recreational fishery. As an established species, it will be next to impossible to completely eradicate them from the Bay. And, if they are adding value, is it worth the time and expense to try removing them?
This debate is happening around the world because humans, as we travel the globe, transport more than just ourselves, whether on purpose or accidentally. And everywhere we go, we tend to shift the landscape (or waterscape) to our needs, which alters ecosystems; creating space for nonnative species to gain a foothold, altering the distribution of native species, or even leading to extinction of some species.
When an ecosystem has been changed, it’s very difficult to go back to the way it was before because it is a dynamic system. When one thing changes, everything else will adjust accordingly and we don’t always know what that will look like – from introducing these invasive catfish initially and not understanding the impact they would have, to the potential changes that would occur if we actually succeed in removing the invasive species once they’ve been established.
So, with all of this in mind, what is the solution? For the invasive catfish species in the Chesapeake Bay, the answer is to catch and eat these fish. By encouraging the removal of these species through fisheries, we are participating in the valuable aspect of these invasive species, while also helping to control the population. This is especially important because in order to better understand the role of these invasive species, scientists and wildlife managers need to continue to study these animals before we attempt complete eradication. If the populations of these species continue to climb, we may have to resort to more drastic methods of population control, which could have unintended consequences.
If you want to help monitor this situation and keep catfish populations in check, target these species while fishing in the Bay. If you accidentally catch one of these invasive species while fishing for something else, don’t release them, even if you aren’t interested in eating it yourself. If you catch one, be sure to report it to the Maryland Department of Natural Resources here.
Even if you don’t fish, you can seek out local blue and flathead catfish to purchase, helping support those who are working to keep these fish populations in check. Because managers are encouraging people to eat these species, there are lots of recipes available online and you may even find them on the menu in some restaurants and even in the food stalls at Camden Yards (read more here).
Eating these invasive catfish is another tasty way to support a healthy Chesapeake Bay!