A comparison of catchment based salmonid habitat survey techniques in three river systems in Northern Ireland

Three survey techniques, a fully quantitative, multivariate study; a shorter or truncated fully quantitative method and a Geographical Information System (GIS) based, semi-quantitative, survey technique, were developed to assess in-river salmonid habitats on a catchment wide basis. These methods were tested and compared on three river systems in Northern Ireland: the Blackwater, the Bush and the Main. The research indicated that the fully quantitative method generated an accurate habitat database but required a high investment in time and resources to complete. The truncated survey approach often produced an inaccurate habitat database. The semi-quantitative technique generated a more accurate habitat dataset with greater productivity and efficiency for the resources invested in the survey.