Report on Harmonisation of freshwater biological methods

iverin order to obtain a representative sample. One passage is performed. Stop netsare not usually used, but are used in some specific cases. The preferred season forelectric fishing extends from late summer to early autumn.144. In non-wadable rivers, electric fishing is performed from a boat, usually by 4persons, with a 7 KW DC generator. The representative method is used.Greece145. In Greece, there is no nation-wide system of fish data collection, and,therefore, there are no nationally standardised sampling methods. The collection offish data allowing the evaluation of the type and magnitude of impacts on the aquaticenvironment has never been a sampling objective. As a consequence, samplingtechniques have not been appropriately standardised for purposes of water qualityassessments.146. Although samples have been collected with a variety of fishing techniques(gill nets, seine netting, fyke nets, fry nets, fish pass control, etc.), electric fishing hasalways been a basic component of all riverine investigations. Data exclusively fromwadable rivers, collected in spring if the investigation is targeted to aspects ofreproduction and early life stages and in late summer or autumn if the target is thestudy of human impacts and threats to endangered species. DC electric generators(300-600 V) are used. The usual sampling practice is one person operating the anodeproceeds upstream (sampling stretches of 40-100 m) and one or two other personswith hand-nets follow behind. One passage is performed, and no stop nets are used.Lithuania147. Several sampling gears are currently used in Lithuania. The most extensivelyused method is electric fishing, representing 88% of the sampling sites, 54% bywading and 34% from a boat. Other methods include stationary gill netting, and theuse of drift and dragnets.148. In wadable rivers, electric fishing is performed with a 600 V PDC battery,usually involving 3 persons of whom one operates the anode. The sampling intensitydepends on the river size. Usually, one site per 10 km length river segment isinvestigated, with the sampling site covering 100-200 m. For each site, 1-3 passagesare performed (in most cases 2 passages) and no stop nets are used. The preferred99