Grass Carp Populations Invade the Great Lakes

Grass carp

Experts discovered that fertile grass carps have invaded the Great Lakes of Michigan, Erie, and Ontario

American and Canadian experts developed a study that reports of grass carps that have invaded the freshwater lakes of Michigan, Erie, and Ontario. This represents a serious threat to the ecosystem of the lakes.

The grass carp is one of the four species of Asian carp and is an herbivorous fish that lives in freshwater. It weighs up to 90 lbs. and is does not a native of American and European lakes.

The grass carp was brought to the U.S. in the 1960s to keep the weed growth in waterways under control. Some of them escaped of the system and swam north, eventually reaching the Great Lakes. This is not the first time when these fish were seen in the lakes.

Two breeds of grass carp are regarded as the most dangerous. The bighead grass carp and the silver grass carp put the aquatic ecosystem in danger as they eat large quantities of microscopic plants and animals. They are also a threat to other fish in the lakes since they are incredibly invasive and compete with the native species of fish for food until they end up overtaking the ecosystem.

The experts who developed the research received help from Fisheries and Oceans Canada, the U.S. Fish and Wildlife services, and the Great Lakes Fisheries Commission. They found that nine out of ten carps they caught from 2013 to 2016 were fertile.

Many grass carps have been found in the Great Lakes, but they were generally thought to be fertile. The assumption is that fertile carps made their way from the south into the lakes and gradually birthed many generations of other fertile fish.

The carps have been in the lakes for about 30 years, but they were not supposed to be fertile. They used to lay somewhere in the background in the freshwater environment of the Great Lakes and never posed a risk for the environment. Also, the carps released from the hatcheries into the waters were sterile. Somehow, they found a way to enhance their fertility.

Action needs to be taken, since grass carp population threaten to become established in the Great Lakes area in about ten years. The authorities are planning to enforce strict laws on bringing grass carps into the area and also prevent the release of fertile fish in the waters. They have also thought of setting up nets that keep the fish away from the spawning sites during reproduction.
Image Source: Wikimedia Commons

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