The first record of a domestic invasive species Opsariichthys platypus in the Hija River, Okinawa Island

DOI IR IR (HANDLE) Open Access

Bibliographic Information

Other Title
  • 沖縄島中部の比謝川で移入・定着が確認されたオイカワ

Description

In October 2023, Opsariichthys platypus, a species native to mainland Japan, was first collected in the Hija River, Okinawa Island. Additional surveys were conducted between October 2023 and March 2024 across seven study sites in the Hija River area. These surveys were conducted by both collecting specimens and visual inspections. Opsariichthys platypus specimens of various sizes were collected at two sites. Furthermore, 100–1000 individuals were visually confirmed at four sites. Molecular analyses of the 16S rRNA and COI genes demonstrated a substantial similarity between the collected specimens and those from mainland Japan, suggesting successful establishment after introduction in the Hija River. The introduction of O. platypus into the Hija River was theorized to have occurred due to one or more of eight potential factors, including the release of ornamental fish or bait fish for fishing. However, identifying specific factors was very difficult due to the rapid increase of the introduced O. platypus population. To prevent the potential spread of O. platypus to other rivers in the Ryukyu Archipelago, we aim for O. platypus to be designated by Okinawa Prefecture as an invasive species based on prefectural regulations. Additionally, an urgent approach to better manage and control family Cyprinidae species having similar life histories is needed.

Journal

  • Fauna Ryukyuana

    Fauna Ryukyuana 72 1-13, 2025-03-05

    Fujukan, Museum of the University of the Ryukyus

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