Report on Harmonisation of freshwater biological methods
Report on Harmonisation of freshwater biological methods
Report on Harmonisation of freshwater biological methods
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26. The sampling frequency is variable generally 2-12 times per year (Fig. 25), withsummer and autumn as the most comm<strong>on</strong> sampling seas<strong>on</strong>s (Fig. 26).Sampling frequencyNOMECEBAAT12-67-12+12AL0 20 40 60 80 100Figure 25. Fish sampling frequency in the GIGs.Sampling period%80706050403020100AL AT BA CE ME NOWhole yearVegetati<strong>on</strong> periodIce free periodWinterSpringSummerAutumnFigure 26. Fish sampling frequency in the GIGs.27. Table 6 describes the sampling <strong>methods</strong> and metrics for fishes. It shows a widenumber <strong>of</strong> sampling approaches and metrics. A total <strong>of</strong> 13 countries are samplingfishes in lakes using a total <strong>of</strong> 7 different approaches, either al<strong>on</strong>e or in combinati<strong>on</strong>,that are used for gathering the informati<strong>on</strong>: net fishing (gillnets and trammel net),electr<strong>of</strong>ishing, hydroacoustics, catch statistics, informati<strong>on</strong> from anglers and historicdata. The majority <strong>of</strong> the countries determine species compositi<strong>on</strong>, some the nativespecies and or functi<strong>on</strong>al group ratios. Fish abundance is determined as total biomass,relative biomass (CPUE), either for the whole fish community per species, and as65