Benefits Provided by Freshwater Fish Standard Sampling in Management

Standard sampling of fish assemblages in lakes and streams is an important part of environmental monitoring programs, including monitoring of large-scale management to mitigate negative effects of anthropogenic acidification. We give examples of benefits provided by use of two European standard methods, i.e. sampling of fish with electricity (EN 14011:2003) and sampling of fish with multi-mesh gillnets (EN 14757:2005). In the 21th century these methods were increasingly used as a basis for assessing ecological status, according to the EU Water framework directive (2000/60/EC). Both standard methods were more or less consistent with procedures already used in Swedish monitoring programs for a decade or longer. Benefits of large-scale sampling, in space and time, with standard methods further rely on quality assured data in nationally managed and publically accessible data bases. We present use of the National Register of Survey test-fishing (NORS) and the Swedish Electrofishing Register (SERS). A recent evaluation showed the importance of long-term liming (1982-2012) of acidified streams and rivers, for slowly achieving positive effects on fish populations and assemblages on a national scale. Preliminary results of a similar evaluation of long-term liming of acidified lakes will also be presented.