The signal crayfish, classified as an invasive species harmful to local ecosystems, has recently been found in the Tonegawa river water system in Chiba Prefecture.
Environment Ministry officials have said it is the first time the signal crayfish has been confirmed in the Kanto region.
Chiba prefectural government officials are investigating whether signal crayfish are proliferating in wider water areas throughout the prefecture.
Signal crayfish are indigenous to North America and measure about 10 centimeters to 15 centimeters. They are known to be voracious eaters of native snails, small fish, fish eggs and plants, and cause further damage to the environment by making burrows and eroding river banks.
Read the rest of the story: Alien crayfish found in Tonegawa river system