Influence of modern irrigation, drainage system and water management on spawning migration of mud loach, Misgurnus anguillicaudatus C.

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• 作者：Yasufumi Fujimoto ; Yutaka Ouchi ; Takeshi Hakuba ; Hiroaki Chiba and Munehico Iwata
• 关键词：Environment preservation ; Misgurnus anguillicaudatus ; Mud loach ; Paddy field ; Reproductive physiology ; Spawning migration
• 刊名：Environmental Biology of Fishes
• 出版年：2008
• 出版时间：February, 2008
• 年：2008
• 卷：81
• 期：2
• 页码：185-194
• 全文大小：452.2 KB
• 刊物类别：Earth and Environmental Science
• 刊物主题：Environment
  Environment
  Nature Conservation
  Animal Systematics/Taxonomy/ Biogeography
  Zoology
  Hydrobiology
  
• 出版者：Springer Netherlands
• ISSN：1573-5133

文摘

We investigated the influence of human activities on the spawning migration of the mud loach, Misgurnus anguillicaudatus. Mud loaches migrate from rivers to paddy fields for spawning. In this study, the number of adult loaches in paddy fields showed a peak in late May and rapidly decreased in July. In early July, water is discharged from paddy fields in order to allow the fields to dry for a few weeks, and water is again supplied later. The spawning season of the loaches probably spans from mid May to August; this was concluded by observing physiological indicators such as the gonad somatic index, oocyte maturity and serum levels of testosterone, estradiol-17β and 17α, 20β-dihydroxy-4-pregnen-3-one. When the loaches mature, they migrated to paddy fields if they could swim upward through the drainage ditches. However, the drainage ditches of modern paddy fields were reconstructed to deepen the water levels. The artificial drought of the rice culture management led to a discharge of water and loaches from the paddy fields during their spawning season. These results indicate that modern rice cultivation causes obstruction of the migration route and loss of spawning grounds; consequently, loaches use limited space and period of the paddy field for their spawning.