How Asian Carp are Threatening US Waterways
In the 1970s, Southern farmers thought they had discovered the perfect way to protect their ponds from algal blooms, and they imported hundreds of Asian carp. But unfortunately the carp outsmarted them, and they managed to jump from the ponds into the Mississippi River. From there they reproduced at rapid rates, spreading throughout the eastern and midwestern United States. That’s where we are today- trying in vain to stop them from spreading further and taking over even more waterways. But why? Well, the harmless looking fish is a lot more dangerous than the farmers who brought them over ever realized.
For starters, the fish reproduce at alarming rates. One fish can produce hundreds of thousands of eggs, many of which will go on to survive if the eggs were laid in open river areas.
This is a problem considering that the main locations for the carp are the Mississippi and Missouri rivers. As the population of the carp increases, the populations of native fish species decreases. This hurts the fishing industry, tourism industry, and many local businesses. For example, some areas of the Mississippi River have been recorded as having fish populations that were 90% Asian carp. This is a staggering statistic considering that carp aren’t even native and weren’t introduced until the 70s. This lack of native fish is a concern especially for sport fishermen who want to keep a healthy population of perch and bass in their waters. Some fishermen have responded by holding Asian carp fishing tournaments. Betty DeFord started one on the Illinois River, The Redneck Fishing Tournament, and it’s been held for several years in a row now. It garnered international attention, with fishermen coming from all over the world to participate in 2021.
Aside from the carp’s effects on other fish, they also reduce the populations of freshwater mussels. This is for two reasons: black carp, a type of Asian carp, eat the mussels, and the carp as a whole reduce the populations of largemouth bass, which are needed for the mussels to reproduce. The bass carry the mussels’ eggs across the lakes and rivers and allow them to populate. Asian carp aren’t able to do this, so as they cause less bass to be available they make it more difficult for the mussels to reproduce. This is harmful because freshwater mussels are already endangered and are vital to water quality. They filter contaminants out of the water, which makes it safer for animals to drink and easier for companies to make it potable for humans. They also oxygenate water, meaning that without them dead zones would begin to form. Dead zones are areas where a lack of oxygen makes it impossible for aquatic life to survive. This often leads to algal blooms because there are no fish to eat the algae. Algal blooms let illnesses spread at rapid rates through bodies of water to both humans and animals, and unless the population growth of Asian carp decreases from its current trajectory, we’re going to start seeing those effects soon.
Another effect that Asian carp have is the reduction of vegetation in wetlands. Grass carp specifically eat large amounts of vegetation no matter where they are, and once they get into wetlands they can wreak havoc. The plants in wetlands are needed to prevent runoff from contaminating the water. And, according to The Invasive Species Centre of Canada, “Just 10 Grass Carp per hectare can reduce wetland vegetation by up to 50%.” This makes them a serious threat to the future of wetlands, which are important in filtering carbon out of the atmosphere. At a time when carbon emissions are a major target of countries looking to prevent climate change, we can’t afford to let our progress be lost to the carp.
As of 2021, several government agencies, such as the EPA and the DOI, are working to prevent the spread of Asian carp to the rest of the United States and to reduce the current population. What started out as an experiment to help Southern farmers has turned into a race against the clock to prevent disastrous damages to native fish, water quality, and wetlands.
