|Book of abstracts, 22nd International Biophysics Symposium, Sveti Stefan, Serbia and Montenegro, 9th-14th October 2004, W2:P6
CHANGES OF STERLET (ACIPENSER RUTHENUS L.) POPULATION AGE STRUCTURE IN THE DANUBE RIVER DURING LAST HALF OF TWENTIETH CENTURY
Lenhardt§, M., Cvijanovic‡,G. Kolarevic‡, J., Jaric‡, I. and Cakic§, P.
‡Centre for Multidisciplinary Studies, Kneza Viseslava 1, 11000 Belgrade, Serbia and Montenegro
§Institute for Biological Research, 29 Novembra 142, 11000 Belgrade, Serbia and Montenegro
Sterlet (Acipenser ruthenus L.) is considered as endangered species in most parts of its distribution. In Serbia and Montenegro it is considered as species with low risk of endangerment, which could be partly explained with deficiency of available data, concerning state of its populations. Last survey, considering this problem, was performed more than a forty years ago. Therefore, analysis of age structure and its changes was performed on 467 specimens, obtained on 1173 river kilometer of the Danube River. Age was determined using pectoral – fin spine sections according to Stevenson & Secor method. All specimens were in age classes between 0+ and 2+. Around 89% of analyzed species belongs to the youngest age group, 10.5% were 1+ and only 0.2% were 2+ sterlet specimens. Aquired results were compared with earlier findings from mid sixties of the last century. Results indicated drastic change in sterlet age structure, and significant shift from older to younger age classes. These changes could be caused by different impacts, such as over-exploitation, river regulation and pollution. Decrease in number of adult and mature specimens, which indicates deterioration of sterlet population, should be sufficient reason for revision of sterlet status in national legislative.