Any lamprey surveys needs to be preceded by a lamprey habitat survey, to allow surveys sites to be picked in advanced. This is probably the most important part of the sure, as it will determine which sites you will end up sampling. Optimal habitat for juvenile lampreys would be areas where several square meters of stable fine sediment overlain with a layer of fine organic detritus occur. These areas are also likely to be be shaded and occur in slow flowing stretches of a river.
Sub-optimal habitat would include areas characterised by patchy shallow covering of fine sediment interspersed among coarse gravel. Unsuitable habitat areas include areas where the substrate was dominated by rock and had little or no sediment. Areas of a river which have been recently dredged would also have to be classified as being sub-optimal habitat. The presence of potential spawning habitat in the channel was also noted and defined as the upper limits of riffles where cobbles and pebbles area present. Lampreys often spawn in the same areas as salmon (sea lampreys and river lampreys) and brown trout (brook lampreys), with lamprey spawning often occurring in areas downstream of barriers to migration (i,e, artificial weirs, natural waterfalls etc.). Advance habitat surveys provide an estimate of the linear extent of optimal and sub-optimal habitat for each survey stretch (measured as m of habitat per km of river bank).
Detailed habitat information is recorded at each sub-site, including the following methdologies:
Also, for further information please do not hesitate to contact us.