Aquatic Invasive Species

Aquatic Invasive Species Two thirds of the forty freshwater fish extinctions are known to have been caused by invasive species. The extinctions could have been caused by any one of the four thousand three hundred known invasive species in the United States. In Minnesota, the land of ten thousand lakes, thirty-five percent of all recreational waters are known to hold at least one invasive species (Invasive species of aquatic plants and wild animals in Minnesota: Annual report). The common carp, zebra mussels, Eurasian watermilfoil, and the northern snakehead are just a few of the most common and most threatening invasive species. The common carp is a species that has been spread because of fisherman that dumped juvenile carp that they were
using as bait into the water. The carp has become a very abundant species, causing detrimental effects on aquatic habitats, including destroying vegetation and increasing water turbidity. They also affect the abundance and diversity of native species (What Are Aquatic Invasive Species). Zebra mussels are a species that were most likely introduced as a food source in the Great Lakes. The mussels then repopulated through the Mississippi river and its tributaries. The mussels are able to move from lake to lake by attaching themselves to boat hulls and trailers. If the boat is not washed off before entering another lake, the mussels may detach themselves in the new lake, then repopulating there. The zebra mussels decrease the native mussel populations, while also clogging water intake pipes. Millions of dollars have been spent to try and control and eradicate zebra mussels, but without success (What Are Aquatic Invasive Species). Eurasian watermilfoil is a plant that was most likely introduced hundreds of years ago as a food source.
Like zebra mussels, they were first introduced in the Great Lakes, then found a way into the Mississippi. Of an inspection by the U.S. Geological Survey of watercrafts that were traveling on a road, twenty-three percent of the watercrafts had watermilfoil attached to them. The plant can grow higher than other native species, forming a canopy that shades other plants and prevents them from growing. This replaces and reduces the diversity of native aquatic species. Fish rely on plants to eat, and Eurasian watermilfoil provides a smaller abundance of food than native species. Other than destroying other plants, the Eurasian watermilfoil also degrades water quality, reduces oxygen levels in the water, and can restrict recreation such as swimming, boating, and fishing. Just like the zebra mussels, they can also clog water pipes (Nonindigenous Aquatic
Species). The northern snakehead is another fish that was introduced as a food source.
The snakehead were introduced in small numbers, but can lay eggs that hatch within two to three days, often spawning up to fifteen hundred eggs five times a year. A unique characteristic of the snakehead that allows it to move from pond to pond is its ability to travel on land. Although the snakehead moves slowly on land, they are able to stay out of the water up to two to three days at a time. Snakehead are aggressive feeders, competing with and preying on native fish species. Over ninety-seven percent of the snakehead’s diet is native fish. The other three percent is a mix of insects, crustaceans, and frogs. Snakehead have even been known to attack swimmers if they feel threatened (Nonindigenous Aquatic Species). The common carp, zebra mussel, Eurasian watermilfoil, and northern snakehead are all invasive species that have caused a lot of problems and money to be spent to try a contain them. Their effects on the ecology and on native species are disturbing, and are continuing to get worse. None of the invasive species would have been able to spread if fisherman and boaters followed the state laws of washing a boat when changing lakes, not dumping any unwanted bait into the lakes, and not releasing any non-native species into waters without the consent of regional wildlife
officers.