[The harvestable part of narrow-clawed crayfish population produce in Svetlogorsk reservoir]
2005
Alekhnovich, A.V. | Kulesh, V.F.(The National Academy of Sciences, Minsk (Belarus). Institute of Zoology)
Biological characteristic of Svetlogorsk reservoir is examined. It has been found that macrofit biomass varies from 2-3kg/square m to at least 10kg/square m of raw substance. The total number of zooplankton with the dominating Ceriodaphina pulhella, Bosmina longirostris species in June was 148 800 species/square m. The most varied group is hironomid, dragonfly larvas and molluscum. The quantity of narrow-clawed crayfish was estimated in various habitats. The quantity of crayfish in shoaling water of the gulf was on the average 0,2 individual/square m, in minor shoaling water -1,85 individual/square m, in the depths it varied from 2,3 to 4,3 individual/square m. So the average quantity of crayfish in the reservoir is o,6+-0,85 individual/square m. If the total reservoir area is 300 hectare, the harvestable part of crayfish population will be approximately 1 800 000 individuals. The harvestable part of narrow-clawed crayfish population produce was estimated. Harvestable crayfish are species from 2+ till 5+ yeas old. The major harvestable crayfish species are 3+years old. The total produce of harvestable part of narrow-clawed crayfish population in Svetlogorsk reservoir is 25,5 632,8kg (26,5tons) every year, which corresponds to 85,6kg/hectare. Annual somatic produce of harvesting part of narrow-clawed crayfish population in Svetlogorsk reservoir us almost twice more productive than noble crayfish population in Lithuania and is practically compared with one of the most crayfish-productive lakes in Belarus - Oltush. Harvest comprises 20% of the produce. Annual P/B (the relation of production to biomass) somatic produce coefficient of male and female equals 0,58 and 0,47 corespondingly, the average P/B of harvesting part of the population is 0,53
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