Red swamp crayfish, designated as a subject for emergency measures against invasive alien species, were caught Friday in a pond at Shinsui Park near Nagura Dam in Tonoshiro, Ishigaki City. This was the first time the species was found in Yaeyama area, and the discovery prompted officials at the Ishigaki Nature Conservation Office to worry about the impact on native species.

According to the Conservation Office, so far 200 – 300 red swamp crayfish from the pond have been exterminated, but the action does not necessarily guarantee the complete eradication of the species. Reportedly, the office first received information about the crayfish in early July.

The red swamp crayfish is a crustacean native to southern United States, and was in 2015 designated as a subject for emergency measures against invasive alien species. They have a high fertility rate, and may adversely affect native species like freshwater prawns or freshwater fish.

Water in the pond at Shinsui Park flows in from a swampland at the foot of a nearby hill, and then flows out into Nagura Dam. The crayfish were found only in the Shinsui Park pond, however, Ishigaki City is taking urgent measures to exterminate them before they spread further.

Officials have advised residents not to take crayfish from the park, and ask those who already have taken them, to not release them in other areas. They urge people to think about effects on local species that would likely be damaged.

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