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2003 Fiscal Year Final Research Report Summary

The study on the conservation and management of ayu, Plecoglossus altivelis, populations in the Kasumigaura Lake system, Ibaraki Prefecture, Japan.

Research Project

Project/Area Number 13660191
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field General fisheries
Research InstitutionKitasato University

Principal Investigator

IDA Hitoshi  Kitasato University, School of Fisheries Sciences, Professor, 水産学部, 教授 (90050533)

Co-Investigator(Kenkyū-buntansha) SUNO Noriyuki  Ibaraki Prefectural Freshwater Fisheries Experimental Station, department of riverine system, senior stuff, 河川部, 主任
HAYASHIZAKI Ken-ichi  Kitasato University, School of Fisheries Sciences, Lecturer, 水産学部, 講師 (80208636)
Project Period (FY) 2001 – 2003
Keywordsayu / growth / land locked / DNA / otholith / food selectivity / gene diversity / gill taker length
Research Abstract

Ayu, Plecoglossus altivelis recently proliferated in the Kasumigaura Lake was studied. From the allozyme analysis the population was identified as an amphidromous type with the neighboring rivers populations but making slightly different sabcluster. By the electron microplobe analysis(EPMA), Sr/Ca ratio in otolith was measured, and was found that the population of the lake system did not have the stage in the coastal area. In the juvenile stage, nauplius of copepods with other zooplankton were found to be the main food item, but in the later stage in the lake, cyclopoids and then mysids dominated as the main food items. After entering flowing Koise River, Ayu shifted food item to benthic algae with some addition of aquatic insects. From the analysis of daily growth ring on the otolith, the modes of growth of individuals from both the lake system and the neighboring rivers were compared. Because of extreme lowering of the water temperature of the lake system in winter, the growth of Ayu was scanted and the stunted growth resulted making a transparent zone without daily rings on the otolith. But the stunted growth was compensated by the faster growth by warmer water temperature in late spring to early summer and the body size in summer was not less than that of the amphidromous neighboring river groups. Estimation of the spawning date from the daily rugs on the otolith was made using individuals collected by January, thus lacking transparent zone on the otolith, the spawning season was determined as October to November. The growth rates an tie were compared and was found that those after the wintering was higher than those before the wiring. Analysis of mitochondria and genomic DNA suggested the genetic diversity of the Ayu population of the lake system was similar with that of the neighboring river population and there was no trace of the bottle neck effect on the population.

  • Research Products

    (6 results)

All Other

All Publications (6 results)

  • [Publications] Kaewsangk, K., K.Hayashizaki, T.Asahida, H.Ida: "Difference in number of comb-like tooth plates in amphidromous and landlocked populations of the ayu Plecoglossus altivelis."Fisheries Science. 67. 752-754 (2001)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Kaewsangk, K., K.Hayashizaki, T.Asahida, T.Nemoto, H.Ida: "Clarification of the origin of landlocked ayu, Plecoglossus altivelis, populations in the Kasumigaura Lake System, Ibaraki Prefecture, Japan."Fisheries Science. 67. 1175-1177 (2001)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 根本隆夫, 林崎健一, Krittikar Kaewsangk, 朝日田卓, 井田齊, 猿渡敏郎: "アロザイム分析からみた霞ヶ浦水系におけるアユの由来"茨城県内水面水産試験場調査研究報告. 38. 60-63 (2003)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Kaewsangk, K., K.Hayashizaki, T.Asahida, H.Ida: "Difference in number of comb-like tooth plates in amphidromous and landlocked populations of the ayu Plecoglossus altivelis."Fisheries Science. 67. 752-754 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Kaewsangk, K., K.Hayashizaki, T.Asahida, T.Nemoto, H.Ida: "Clarification of the origin of landlocked ayu, Plecoglossus altivelis, populations in the Kasumigaura Lake system, Ibaraki Prefecture, Japan."Fisheries Science. 67. 1175-1177 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Nemoto, T., K.Hayashizaki, Krittikar Kaewsangk, T.Asahida, H.Ida, T.Saruwatari: "The origin of ayu in the Kasumigaura Lake system deduced from allozyme analysis."Bulletin of Ibaraki prefectural freshwater fisheries experimental station. 38. 60-63 (2003)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 2005-04-19  

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