Freshwater Bullhead Survey Data in Wales

Quality Control

Method steps

1. Relevant species abundance data was extracted from the overall spreadsheet supplied with the RoC Report. Where quantitative and semi-quantitative surveys were carried out on the same site at the same time then the semi-quantitative data has not been extracted (as this is a subset of the quantitative data). Historical data for 2001 - 2003: Data was collated from the North Wales Fisheries Monitoring Programme of 2001. A limited number of sites (approximately 12) are fished on an annual basis to obtain information and detect trends within the fish populations and catches. Bullhead populations were also recorded as part of the Dee Stock Assessment Programme on a selection of sites in 2004 and as part of work on the Eel Monitoring Programme at 3 sites in the Dee Catchment for 2004. All sites were surveyed using the electric fishing equipment in accordance with protocols described in the Environment Agency - Electric Fishing Theory and Practice Manual (1988). Two methodologies were employed either quantitative temporal data for sites surveyed annually or semi-quantitative spatial data for sites surveyed every 5 years. Three fishing runs were used for quantitative surveys and one for semi-quantitative surveys.