Ecological Study of the Indo-Pacific Bottlenose Dolphin in Mikura Island, Aimed at Wildlife Conservation

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K12331
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 64040:Social-ecological systems-related
• Research Institution: Tokai University
• Principal Investigator: Kita Yuki 東海大学, 生物学部, 准教授 (30710917)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: ミナミハンドウイルカ / 摂餌生態 / 繁殖生態 / 保全 / 年齢推定

Outline of Final Research Achievements

In order to clarify the reproductive and feeding ecology of the Indo-Pacific bottlenose dolphin that inhabits Mikura Island. We conducted dietary, kinship, and age analyses using 652 fecal DNA samples obtained between 2015 and 2023.
In particular, dietary analysis suggested that the Indo-Pacific bottlenose dolphins that inhabit Mikura Island do not have individual food preferences, and that their main prey consists of four species of fish and two species of cephalopods. Canonical correpondence analysis (CCA) was also performed and differences were detected by month, sex, and maturity stage.
Furthermore, epigenetic analysis was attempted using fecal DNA, and age estimation was successful using degraded genes such as feces.

Free Research Field

鯨類の集団遺伝学

Academic Significance and Societal Importance of the Research Achievements

これまで御蔵島に生息するミナミハンドウイルカの摂餌生態は数個体の胃内容物や行動観察によるもののみで，その全容を捉えられていなかった．海洋生態系で高次捕食者に位置する彼らの摂餌生態を把握することは，彼らの生息する環境の豊かさを多角的に評価する上で重要であることから，本研究成果はその一助となると期待される．
また，糞という劣化した遺伝子からの年齢推定の成功は，目視観察が開始された1994年当初より既に成熟していたとみられる個体の年齢を推定する上で非常に有効であると考えられる．