Report on Harmonisation of freshwater biological methods

density. The age structure or size structure is determined in all but three countries:Poland, Finland and UK.Table 6. Fish sampling and metrics used in different countries within the GIGs..GIG/CountrySampling method Composition metric Quantity metric Age/ size structureALPINEIT net fishing species composition YATDEPLgillnets, electrofishing,hydroacoustics (Gassner, H.and J. Wanzenböck, 1999)catch statistic of professionalfishermen and sport fishing;test-fishinginformation from anglers;historical dataLT selective fish-net, length - 5m,porosity - 14, 18, 22, 25, 36,40, 50, 60 mmEENLGBDEselectiv fish-net, 5m length,porosity - 14, 18, 22, 25, 36,40, 50, 60 mm; Lundgrenmulti-mesh nylonmonofilament gillnetsLundgren type gillnets; trawls(10x1,5 m), mesh 12 mm.hydroacoustics - survey carriedout using a portableechosounder operating at200kHz. Central arm had 10transects with a total length of1935mPoint electro fishing accordingto EN 14011,along transectlines; multimesh gillnetsaccording to Swedish standardnative speciescaught speciesBALTICoccurrence of the fishtaxa on the basis ofanglers' informationor catches; indicatortaxanumber of speciescaptured fishes aresorted by mesh sizeand species, measuredby the total length,number of speciespiscivor./planktivorandpiscivor./omnivor.ratiosCENTRALspecies listsno data available forindividual speciesYmetric tons per year Yabundance inunits/ha andbiomass in kg/haNYabundance in Yunits/ha, biomass inkg/ha, CPUEtotal biomass andspecies share oftotal biomass,CPUEfish density at -50db and fishdensity at -56 dBspecies composition relative abundanceand estimate ofbiomass, CPUEage distribution,size structureMEDITERRANEANES Trammel net, RFAI Method species determination size compositionFI prEN 14757 Water quality –sampling of fish with gillnets;Nordic gillnets in littoral,profundal and pelagic.NORDICnative species,species compositionNYCPUE, number and Yweight66