EIFAC experiments on pelagic fish stock assessment by acoustic methods in Lake Tegel.
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The intention of this exercise was to compare assessments of the fish stock in a shallow lake (x = 6 m) using single- and multi-beam hydroacoustic methods as well as mark-recapture. The experiment included sampling with trawl, seine, and gill-nets. The overall fish population of the pelagic (surface layer excluded) was estimated using single-beam and dual-beam echo sounder (5 % level) to 226 000 – 682 000 fish (> 3 cm) and 195 000 – 425 000 fish (> 2 cm), respectively. The mark-recapture expe riment - which was not confined to the pelagic population - suggested a stock of 554 000 – 736 000 fish (> 13, 11, 16 cm) of three species, bream, white bream, and roach (Abramis brama, Blicca björkna, and Rutilus rutilus) which represent about 84 % of the commercial catch