Technical development for removing the invasive fish using the sterile male release approach

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K14484
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 39060:Conservation of biological resources-related
• Research Institution: Okinawa Churashima Foundation
• Principal Investigator: Oka Shin-ichiro 一般財団法人沖縄美ら島財団(総合研究センター), 総合研究センター 動物研究室, 主任研究員 (00721747)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 外来種 / 駆除 / 不妊化 / SMRT / ティラピア / 魚類 / 淡水魚

Outline of Final Research Achievements

The trials to control the invasive Mozambique tilapia population using the sterile male release technique (SMRT)were performed on the field waters. After three years of direct extermination and SMRT in a closed outdoor artificial pond inhabited by tilapia, the effect of reducing the next generation was unclear even under the condition that about 90% of visible breeding territorial males were occupied by sterile males. In the aquarium experiment, about half of the females had fertilized eggs even under the condition that the ratio of sterile males was 95%, and it was pointed out that the cause was that females mating with multi males. In this study, the contol tilapia population with SMRT was difficult due to their storong reproductive potencial.

Free Research Field

生態学

Academic Significance and Societal Importance of the Research Achievements

外来種対策として直接駆除以外の手法の開発が求められる中，不妊オスによる繁殖阻害で個体数を減じるための脊椎動物で初の手法開発をティラピアをモデルにして行った。3ヵ年にわたる継続的な野外および室内実験の結果から，予想を超えた繁殖力の強さや繁殖システムにより，不妊雄によるコントロールは不可能であると結論付けた。一方で，これまで知られていなかったティラピアの繁殖システムの一端や順応性についても新たな側面を発見できた。いずれにしろ本研究では，当初の目的は達成できなかったものの，ティラピアの駆除の困難さを鮮明に浮き彫りにできた。