The Oriental weatherfish and the Asian swamp eel are freshwater fish that mainly inhabit paddy fields and swampy areas and are widely distributed in East Asia. Both species are also distributed in the Ryukyu Islands, and by being isolated from other areas their existence in Okinawa is considered a native population. However, both species are sharply declining due to the deterioration of their natural habitat, and there are concerns for their survival.

Since both species are also found as aquarium fish and as food items, non-native populations of the fish may be introduced, this leads to concerns over genetic contamination.

Both species were frequently seen in the channel flowing through the grounds of Okinawa Prefecture Hokubu Agricultural High School located in the northern part of Okinawa Island, but no academic surveys had been conducted. When the population density of both species was investigated with the collaboration of the Biological Research Department within the school, high densities of the species were found: 4.67 individuals/m² of Oriental weatherfish and 1.78 individuals/m² of Asian swamp eel.

Analysis of the DNA of collected individuals confirmed that all individuals belong to native populations, and therefore these are valuable populations which should be preserved. Working together with the school, conservation of this habitat is considered to be undertaken.

Authors

Kei Miyamoto¹、Shin-ichiro Oka¹、Hajime Yonamine²、Suzuka Agarie²、Hina Genba²、Nozomi Hanahara^1
1Okinawa Churashima Foundation、²Okinawa Prefectural Hokubu Agricultural High School

Title

A high-density habitat and genetic characteristics of the Oriental weatherfish, Misgurnus anguillicaudatus, and the Asian swamp eel, Monopterus albus, found in Nago City, Okinawa-jima Island, southwestern Japan.

Journal

Fauna Ryukyuana 34: 15-20.

Link

http://w3.u-ryukyu.ac.jp/naruse/lab/Fauna_Ryukyuana.html

Collected specimens of the Oriental weatherfish (A) and Asian swamp eel (B)