A study seems to confirm the fact that grass carps, an Asian species, are in the process of invading the waters of three of the Great Lakes. These are lakes Erie, Ontario, and Michigan.
Grass carps are large freshwater fish. The species is native to the eastern Asia regions. It is a herbivorous fish that can nonetheless grow quite large. Reports show that grass carps have the largest aquaculture production. At a global level, they register more than five million tons every year.
Grass carps are also known as white amur in the United States. They were introduced as a way to control aquatic weed. They first started being grown in the early 1960’s.
Still, some specimens escaped their designated areas. they made their way north. Eventually, grass carps settled in the waters of the Great Lakes. The species has been detected more than once in the area.
A recent report shows that the species has once again entered the fresh water great lakes. It has been spotted in the Erie, Ontario, and Michigan lakes. A Grass carp invasion could be quite damaging for the area. The 90 lbs. fish could threaten the native ecosystem.
Grass carps are considered to be one of the most invasive fish species. Two of its subtypes are the most feared. These are the Silver Grass carp. And also the Bighead Grass carp. These can be a pose a serious threat to an aquatic ecosystem. They feed in quite huge quantities. Their preferred food source? Microscopic animals and plants.
Grass carps are especially feared as they “aggressively outcompete” the native species. They compete for food and feed in abundance. Eventually, they can potentially even overtake control over the respective system.
A scientific report took a closer look at the species. This was prepared by a collaboration between the American and Canadian authorities. The U.S. Fish and Wildlife Services and the Fisheries and Oceans Canada contributed. As did the Great Lakes Fisheries Commission.
According to their report, the lakes could be faced with a serious problem. The authorities analyzed fish caught from 2013 to 2016. In 9 out of every 10 cases, the fish were proven fertile. If these continue reproducing, they may come to surpass the local population numbers.
These fertile fish are not believed to be native to the area. They could have been born in another region. Eventually, they could have made their way to the great lakes.
Mark Gaden went to offer details. He is part of the Great Lakes Fishery Commission. According to Gaden, Grass carps found in the area were typically sterile. But lately, this trend has changed. Fertile fish are becoming increasingly more common.
Becky Cudmore, the report’s lead author, also released a statement. Cudmore pointed out the following. For the moment, sterile fish still outnumber the fertile ones.
Still, this situation may change within a decade. If action is not taken, Grass carps may become an “established” species. Such specimens would have to breed over several generations in the same waters.
This may take place in both lakes Erie, Hudson, and Ontario. As well as in lakes Huron and Michigan. According to Cudmore, Grass carps are starting their invasion of the area. They were spotted before, but now they have actually “arrived”.
The situation can still be controlled. Grass carp import restrictions could be placed. Fertile fish could stop being released back into the lake waters. During reproduction periods, nets could be set so as to stop the fish from migrating further inside.
Image Source: Wikimedia
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