Age and Growth of the European Bitterling Rhodeus amarus (Cyprinidae, Actinopterygii), in the Uday and Perevod Rivers (Dnipro basin, Ukraine)

Abstract

Age and growth of the European bitterling were investigated in the Uday River and the Perevod River at the National Nature Park "Pyriatynsky" (Poltava region, Ukraine) in 2017–19. The studied population of the European bitterling was represented by five age groups (0+ to 4+). Age was determined by counting annuli on scales. Scale annuli were visible and often displayed as irregularities in circuli in the centrolateral part of the scales. Fish standard length varied from 14 to 51 mm, weight – from 0.09 to 2.5 g. The length-weight relationship was W=0.00005*TL2.78; W♂=0.00048*TL2.18; W♀=0.00028*TL2.32 for both sexes, males and females, respectively. The sex ratio was 1:1.26. The most abundant group in the samples from the Uday River were young-of-the-years, in the samples from the Perevod River – 1+ fish. As for mature specimens, 3+ fish predominated in both samples. The fastest relative growth was during the second year of life.

Keywords

• bitterling
• scale
• length-weight relationship