Studies on pathogenicity and control method in flagellates infecting juvenile chum salmon in seawater

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K05736
• 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: Hokkaido Research Organization
• Principal Investigator: Mizuno Shinya 地方独立行政法人北海道立総合研究機構, 水産研究本部 さけます・内水面水産試験場, センター長 (70442655)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: サケ稚魚 / イクチオボド / スピロヌクレウス / 海水適応能 / オキソリン酸

Outline of Final Research Achievements

Present study examined pathogenicity and control method in two flagellates, Ichthyobodo salmonis and Spironucleus salmonis, infecting juvenile chum salmon in seawater. Some freshwater-adapting juvenile chum salmon infected with either I. salmonis or S. salmonis showed mortality after transferring to seawater, which suggested that infection of either I. salmonis or S. salmonis in freshwater caused early mortality after migration to sea in juvenile chum salmon. In addition, infection of both I. salmonis and S. salmonis are probably controled by feeding commercial trout diet supplemented with proprietary food and administration of oxolinic acid in seawater-adapting juvenile chum salmon.

Free Research Field

魚類生理学

Academic Significance and Societal Importance of the Research Achievements

・鞭毛虫が検出された孵化場に対し、淡水中稚魚への本虫の寄生が降海後サケの初期減耗要因となる可能性を説明し、注意喚起を促すことにより、現場で本虫の防疫について意識を高めることができた。
・開発した総合的防除技術は、サケ海中飼育事業で鞭毛虫の有効な対策として活用できる可能性がある。