Report on Harmonisation of freshwater biological methods

ut comparisons have been made with sampling performed during the night,indicating that the abundance, frequency and size of species caught vary greatlybetween day and night. Additional techniques of fish sampling in non-wadable riversinclude seining (used in straight canals with width less than 30 m), fyke nets (inconnection between main channel and backwaters), and control of fish pass and sportangler catches.France139. Electric fishing is the usual method of fish sampling employed nation-wide.The preferred season for sampling is autumn, but sampling in small and mediumsizedwadable rivers is also performed in late spring and summer.140. In streams, fishing is conducted over the whole river width, moving fromdownstream to upstream. The sampling area is delimited by two stop nets. During onepassage (or more), several anodes depending on the river width) are moved in thewater and followed by hand-nets (4mm-mesh size) for collecting fishes. Each anode isgenerally followed by 2 hand with suitable vessels for transporting fish.141. In wadable rivers, several sampling protocols have been successively tested:the first one was implemented in 1981. The procedure consisted of “continuous banksampling”, the second protocol used is “point abundance sampling” (Persat and Copp,1990) and the third protocol was introduced in 1995 and derives from Pouilly (1994)and Capra (1995) and is called “ambience sampling”.Germany142. A standardised German river monitoring system has never been establisheddue to the special situation in Germany where inland fisheries is under theresponsibility of Federal States. Each Federal State has its own river monitoringprogrammes and maintains their own database. Only for some large rivers as Rhine orElbe are fish monitoring systems coordinated by the affected Federal States orcountries. For example, the Federal State of Baden-Wuerttemberg use the followsampling procedures:143. In wadable rivers, electric fishing is performed using a DC 1,5-7 KW electricgenerator. For a given site, the sampling area is at least 100 m in small headwaterstreams and increases with increasing size and habitat complexity of the sampled98