Establishment of the invasive brown trout Salmo trutta in the Okita River, Ibaraki Prefecture

The establishment status of invasive brown trout Salmo trutta in the Okita River, Ibaraki Prefecture, Japan, was investigated in July and November 2023, as well as February 2024. A total of 31 individuals (39.4 to 546.0 mm standard length) were collected, and two redds were identified in February 2024, as a result of the surveys. Based on these results, brown trout were determined to be established in the Okita River.