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Title: Regional juvenile salmonid monitoring programme : annual report 1992
Author: National Rivers Authority Welsh Region
Document Type: Monograph
The programme of juvenile salmonid stock monitoring was continued in 1992, the eighth year in succession that such a study has been carried out. The data collected is used to form baseline information on the status of juvenile stocks at both a catchment and regional level and can be used to monitor any changes to environmental factors both natural and man-made. As a consequence of the large number of catchments in the Welsh Region (over 50) covering 20,000 km of rivers and streams and given limited resources, not all catchments can be sampled in one year. Therefore, whilst several large 'key' catchments are sampled on an annual basis the smaller catchments are sampled on a rolling programme. Three electrofishing sampling techniques were employed during the period July to September, these being; 1) a catch depletion population estimate on an area of water enclosed by nets - quantitative sampling, 2) a one-catch density on an un-netted site - semi-quantitative site, 3) a five minute sample on an un-netted riffle - 5 minute riffle sample. The method used at each site depends upon the resources available, the level of accuracy required and the nature of the site. For example 5 minute riffle sampling is usually undertaken in main rivers where the use of enclosing nets is impractical.
Publisher: National Rivers Authority
Publication Date: 1993
Publication Place: Cardiff
Subject Keywords: Fishery managementSalmon fisheriesTroutJuvenilesStock assessmentMonitoringAnnual reports
Geographic Keywords: Wales
Taxonomic Keywords: Salmonidae
Extent: n.p. [269]
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