Distribution, spread and habitat preferences of nutria (Myocastor coypus) invading the lower Nakdong River, South Korea

Nutria (Myocastor coypus) were introduced into South Korea in 1985 for fur farming and meat production. However, failures of nutria farm management in the late 1990s resulted in the accidental and/or intentional release of nutria into the wild, and they have spread and become serious pests. The successful management of invasive species like nutria somewhat depends on the comprehensive knowledge of distribution patterns. Therefore, this study aimed to identify the distribution, spread, and habitat preferences of nutria invading the lower Nakdong River in South Korea to facilitate current control and eradication endeavours. Nutria populations were recorded in 45 of 236 sites investigated. The distribution patterns revealed that the spread of nutria from farming sites has mainly proceeded along rivers via tributaries. Important factors associated with the establishment of new populations were food availability, levees with suitable burrow materials, and slow water flow. The winter climate was also important, and the total number of days below -4 degrees C significantly affected nutria occurrence. To date, efforts to control or locally eradicate nutria populations have had little success due to insufficient budgets and the lack of coordinated management activities between local governments. To improve the efficiency of nutria eradication programmes, local governments must establish an integrated and coordinated strategy that is overseen by a single, national agency. To ensure the success of the programmes, this agency should make the best use of ecological information about nutria distribution, and utilize optimal control techniques and timing.