Integrative strategy in behavior and life history: explorative study using PIT tag systems

2021 Fiscal Year Final Research Report

• Project/Area Number: 20K21439
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 45:Biology at organismal to population levels and anthropology, and related fields
• Research Institution: Hokkaido University
• Principal Investigator: Kishida Osamu 北海道大学, 北方生物圏フィールド科学センター, 准教授 (00545626)
• Co-Investigator(Kenkyū-buntansha): 森田 健太郎 北海道大学, 北方生物圏フィールド科学センター, 准教授 (30373468)
• Project Period (FY): 2020-07-30 – 2022-03-31
• Keywords: 回遊 / サケ科魚類 / 生活史 / 多型 / サイズ

Outline of Final Research Achievements

Movement of animals is a key for deepening our understanding of ecology of animals. In this study, we explored what kind of mortality pressure operate on the individuals during their movement, and what tactics animals take against the mortality pressure. We addressed these issues by focusing migration of masu salmon juveniles by conducting individual survey using a PIT tag system. First, we found that river-descending migrants were exposed to size-dependent mortality, in which smaller individuals suffer higher mortality pressure. Second, we showed that smaller migrants exhibited higher growth rate in the pre-migration period and descend the river in later timing than larger migrants. Because the faster growth and later start of migration of smaller migrants allow them to become into larger size before migration, these life history and behavioral pattens represent tactics under size-dependent mortality in the migration.

Free Research Field

動物生態学

Academic Significance and Societal Importance of the Research Achievements

回遊する動物種では，回遊中の死亡から逃れるために回遊前に急成長することが知られていたが，個体が自身の状態に依存してどのような戦術をとるかまではわかっていなかった．本研究では，個体が自身のサイズに応じて，成長速度や回遊のタイミングを変えていることが明らかとなり，回遊する動物種の巧妙な行動と生活史戦術の実態が明らかとなった．