Growth, Diet and Fatty Acid Composition of Gibel Carp Carassius Gibelio in Lake Shira, a Brackish Water Body in Southern Siberia

Abstract

For the first time the presence of gibel carp Carassius gibelio has been detected in the brackish meromictic Lake Shira (Southern Siberia, Republic of Khakassia). Lake Shira has been continuously studied since the late 19th century, and it has been considered so far that there is no ichthyofauna in the lake. This work investigates the growth and population characteristics, as well as food spectra and fatty acid composition of C. gibelio specimen at different ages that were fished out in the summers of 2007 and 2008. The water salinity at the fishing point was 15 g l-1. The food spectrum of one- and two-year old C. gibelio was dominated by diatomic, green and blue-green algae, while four- to sixyear old species had an increased share of copepods, beetles and chironomids in their food spectrum, and beginning from the age of six years the amphipods Gammarus lacustris consisted significant part of gibel carp diet. Thus, it was shown that C. gibelio is a carnivore with regard to the population of amphipods Gammarus lacustris, which have been regarded so far as the upper link in the trophic cascade of Lake Shira. One of the possible reasons for appearance of fish is the decreased water salinity caused by rising of the lake level. In the recent years, the level of Lake Shira exceeded all the values that had been registered since the late 19th century, and the lakes salinity decreased correspondingly to its smallest value for the whole period of observation.

Keywords

• Carassius gibelio
• brackish lake
• food spectrum
• fatty acids