Migratie door een temporele migratiezone en habitatgebruik van vissen in de Itterbeek

Migration by means of temporal migration zones and use of fish habitat in the Itterbeek In the past many water mills had an area that was flooded in periods of high water so that temporal fish migration was possible. The recreation of such temporal migration zones (TMZs) seems a potentially effective measure to restore both fish migration and cultural heritage and landscape values within stream systems in a costeffective manner. This article discusses a telemetry study that was performed in a Dutch lowland stream in 2011 in order to investigate fish migration in TMZs. The study also mapped migration and habitat use downstream of the TMZ. For this study passive integrated transponders (PITs) were inserted into the abdominal cavities of 209 fish larger than 10 cm belonging to 15 different species. This method allowed us to gather information on migration as well as habitat use. Fish migration was observed from the first spring after the construction of the TMZs. Migration occurred mainly during two peaks of the discharge periods. Rheofile species such as chub, gudgeon and loach were most commonly observed. However, the majority of individuals with transmitters turned out to be sedentary and showed little inclination to migrate. Different species had a clear preference for certain types of habitat. Chub and gudgeon preferred the faster flowing sections of streams, but perch had a preference for the structured meandering parts and deep bowls, while bream was mainly found in slowly flowing silty sections and deeper parts. Also two pumpkinseed sunfish used the TMZ to migrate upstream. This indicates the high risk of further spread of this invasive exotic species for our country.