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A ‘Before and After’ Study of the Effects of Land Drainage Works on Fish Stocks in the Upper Reaches of a Lowland River
Author(s) -
Swales Stephen
Publication year - 1982
Publication title -
aquaculture research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.646
H-Index - 89
eISSN - 1365-2109
pISSN - 1355-557X
DOI - 10.1111/j.1365-2109.1982.tb00038.x
Subject(s) - drainage , standing crop , biology , population dynamics of fisheries , fish <actinopterygii> , fishery , period (music) , population density , habitat , hydrology (agriculture) , population , ecology , biomass (ecology) , physics , demography , geotechnical engineering , sociology , acoustics , engineering
Fish stocks at a site in the upstream reaches of the River Soar, a lowland river in Leicestershire, showed a marked alteration following river channel works associated with a land drainage improvement scheme. The density and standing crop of all ‘large‐sized’ fish species present showed reductions of 15–100% between a 6‐month pre‐drainage period and a 3‐month post‐drainage period. The density and standing crop of the total population were reduced from means of 0.160 fish m −2 and 39.0 g m −2 during the pre‐drainage period to means of 0.048 fish m −2 and 9.6 g m −2 during the post‐drainage period, reductions of 70% and 76%, respectively. It is suggested that modifications to physical features of fish habitat, particularly the elimination of in stream cover, were largely responsible for the decreased fish abundance.