Growth rate and condition of common bream (Abramis brama) from the Iskar Reservoir in Bulgaria

Abstract

The paper determines two basic parameters of the bream population from the Iskar Reservoir: age structure and
growth rate. Material was collected in the fall, spring, and summer months from 2012 to 2016. A total of 174 bream
specimens were caught. The analysis of this sample found that 10 age groups were represented. Fish weight from age
groups was approximately as follows: from age group 1 – 5 g; 2 – 32 g; 3 – 108 g; 4 – 218 g; 5 – 265 g; 6 – 374 g; 7 – 534 g; 8
– 651 g; 9 – 867 g; 10 – > 1,000 g. The back calculated standard length was as follows: year 1 – 55 mm; 2 – 108 mm;
3 – 161 mm; 4 – 205 mm.; 5 – 230 mm; 6 – 252 mm; 7 – 286 mm; 8 – 296 mm; 9 – 340 mm; 10 – 367 mm. The findings
support the conclusion that the linear growth rate of bream from Iskar Reservoir is slower than that of fish from the
Danube River basin. Some of the reasons that explain this difference include the dam’s high altitude and the
mountainous climate of the surrounding area, which mean the fish growth period is shorter.