Effects of weirs on fish fauna of the lowest reaches of two tidal rivers draining into the Tone River estuary

• NATSUMEDA Takaharu

  <I>Faculty of Risk and Crisis Management, Chiba Institute of Science</I>

• SEYA Masataka

  <I>Faculty of Risk and Crisis Management, Chiba Institute of Science</I>

Bibliographic Information

Other Title

• 利根川最下流域に流入する感潮河川最下流部の堰が魚類相に及ぼす影響

Abstract

To evaluate the effects of weirs on the distribution of diadromous fish species, we surveyed fish fauna below and above the weir located the lowest reaches of two tidal rivers (Takada and Oshi River) draining into the Tone River estuary in summer(July-August) and autumn(October) in 2010. Of 15 fish species captured, 10(66.7 %) were diadromous fish species. One river with lower weir height(50 cm at max) had diadromous fish both below and above the weir. The other river with higher weir height(55 cm + 130 cm) , on the other hand, had no diadromous fish above the weir, and similarity index between below and above the weir was quite low. Physical environmental condition of the tributary was almost similar between below and above the weir, suggesting weir-induced substantial differences in fish fauna of the tributary. To solve the problem, mitigation of the height of weirs (small-scale fishways and creating a ramp of cobbles and gravels downstream of weirs) might allow diadromous fish passing such instream obstructions during high water level is proposed as a valid management action in tidal rivers.

Journal

• Ecology and Civil Engineering

  Ecology and Civil Engineering 15 (2), 187-195, 2012

  Ecology and Civil Engineering Society

Keywords

• diadromous fishes
• high water level
• mitigation of the height of weir
• tidal river
• Tone River

Details

• CRID: 1390001204472775424
• NII Article ID: 130004541658
• DOI: 10.3825/ece.15.187
• ISSN: 18825974
• ISSN: 13443755
• Text Lang: ja
• Data Source:
  • JaLC
  • Crossref
  • CiNii Articles
• Abstract License Flag: Disallowed