Can spiny lobsters be predators controlling the distribution of herbivorous fishes?

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K06196
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 40030:Aquatic bioproduction science-related
• Research Institution: Fisheries Research and Education Agency
• Principal Investigator: Kawamata Shigeru 国立研究開発法人水産研究・教育機構, 水産技術研究所(神栖), 研究員 (50372066)
• Co-Investigator(Kenkyū-buntansha): 益田 玲爾 京都大学, フィールド科学教育研究センター, 教授 (60324662)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 海洋保護区 / 磯焼け / 藻場

Outline of Final Research Achievements

To test a hypothesis that spiny lobsters can prey not only on sea urchins but also on herbivorous fish such as rabbitfish and parrotfish, we conducted tank feeding experiments and transplantation experiments of kelp Ecklonia cava, which have become extinct for more than 20 years, in a marine protected area (MPA) where lobsters prey on sea urchins and maintain macroalgal beds, while urchin-dominated barrens were common outside of the MPA. The results confirmed that nocturnal lobsters can prey on sleeping rabbitfish in shelters at night, and that in the protected area, only a few very large parrotfish were found to eat the transplanted kelp, supporting the hypothesis that herbivorous fishes, if they exist, are limited to large individuals that have migrated from elsewhere and cannot be preyed upon by lobsters.

Free Research Field

水産工学

Academic Significance and Societal Importance of the Research Achievements

捕食者の乱獲が植食動物であるウニの大量発生を招き、藻場の消失（磯焼け）を引き起こすという栄養カスケード仮説が、海外では多くの全面禁漁区における、捕食者の増加→ウニの減少→藻場の回復という事実により検証されているが、ウニ以外の植食動物についてはほとんど知られていない。小規模な海洋保護区しかない我が国では、ウニの磯焼けに対して有効な保護区はイセエビの保護区以外には見出されていない。また、ウニに加えてアイゴ、ブダイ等の植食魚による海藻食害も問題となっているが、その有効な対策がないことから、イセエビがウニだけでなく、植食魚の捕食者にもなり得るという発見はイセエビの保護区の推進に寄与する。