Evaluation of the effectiveness of bycatch reduction methods using an index of the physiological condition of sea turtles escaping from the setnet

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K05684
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 39060:Conservation of biological resources-related
• Research Institution: Tokyo University of Marine Science and Technology
• Principal Investigator: Shiode Daisuke 東京海洋大学, 学術研究院, 准教授 (40361810)
• Co-Investigator(Kenkyū-buntansha): 奥山 隼一 国立研究開発法人水産研究・教育機構, 水研機構(長崎), 主任研究員 (80452316)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: ウミガメ / 混獲 / 心拍数 / 心電ロガー / 加速度ロガー / 血液性状 / 水温

Outline of Final Research Achievements

Conditions of captured sea turtles and its recovery process from escaping were analyzed for the evaluation of the effectiveness of the turtle releasing system for the setnet. The physiological state (blood properties and heart rate) and behavior of the loggerhead and green turtles were measured with using an ECG logger, an acceleration logger, and a blood property analyzer, and compared in normal times, before escape, and after escape. In both species, the heart rate increased remarkably during the push-up behavior during bycatch, but gradually decreased after escaping the net, and after about 1 day, the heart rate, blood lactate level, and carbon dioxide partial pressure level all returned to normal levels.

Free Research Field

生産システム学

Academic Significance and Societal Importance of the Research Achievements

漁業における混獲問題は，生物多様性保全や生態系の維持を踏まえた持続的な生産体制の構築において極めて重要な課題であるが，混獲回避手法の開発が十分でなく，また混獲状態から逃れた個体の健康状態の把握による有効性の評価例は皆無であった。本研究では，これまで困難であったウミガメ類の心拍計測技術を構築するとともに，心拍数の変動と活動量との関係を整理し，さらに心拍数と血液性状の推移から混獲回避手法の有効性を評価する手法を提示した点で非常に意義深いものである。