Individual and population-level food consumption by cyprinids and percids in a mesotrophic lake Tolonen KT, Karjalainen J, Staff S, Leppä M. Individual and population-K. T. Tolonen, J. Karjalainen, level food consumption by cyprinids and percids in a mesotrophic lake.
S. Staff, M. LeppäAbstract -Mesotrophic Lake Pohjalampi in eastern Finland was fished intensively from 1992 to 1996. In 1996, the biomasses of the dominant fish species, roach and bream, were reduced to 14% and 6%, respectively, of that in 1992. The total biomass of percids was, however, unchanged or slightly increased. The proportion of benthic invertebrates in the total food of the fish decreased from 57% to 36% during the study period, whereas the proportion of zooplankton increased from 31% to 56%. At the same time the number of young planktivorous fish increased. Thus, the main object of fish predation turned from benthic invertebrates to zooplankton due to change in fish population structure. At the beginning percids; mesotrophic lake; biomanipulation of the study the amount of detritus eaten by cyprinids was about 620 kg ¡ ha ª1 ¡ year ª1 , but this decreased by 82% due to the intensive fish-