Aspects of the ecology of bream, Abramis brama (L.), in a gravel pit lake and the effects of reducing the population density.
Abstract
The growth of bream, Abramis brama (L.), in a gravel pit lake was considered to be good in 1982/1983 (Lx=66.5 cm, K=0.105). The adult bream population was dominated by the 1973 and 1976 year-classes. These year classes still formed most of the spawning population in 1987, but had grown very little (<2 cm) in the previous 5 years. In November 1987, 158 kg ha-1 of bream were removed from this lake and in 1988 the remaining bream population showed an increase in growth (mean length by 2.7 cm and mean weight by 0.5 kg) and condition (1.87 in 1987 to 2.09 in 1988) in one growing season. This additional growth of an ageing stunted bream population is considered to be the result of an increased food supply after reducing the fish density.