Age Composition and Growth Rate of the Spawning Part of the Population of Pontic shad Alosa immaculata (Bennett, 1835) in the Bulgarian Sector of Danube River

D. ROZDINA, G. RAIKOVA-PETROVA and P. MIRTCHEVA
Sofia University, Faculty of Biology, Department of Common and Applied Hydrobiology, BG – 1164 Sofia, Bulgaria

Abstract

ROZDINA, D., G. RAIKOVA-PETROVA and P. MIRTCHEVA, 2013. Age composition and growth rate of the spawning part of the population of pontic shad Alosa immaculata (Bennett, 1835) in the Bulgarian sector of Danube River. Bulg. J. Agric. Sci., Supplement 1: 118–125

 

The age structure and the growth ratе of the population of Pontic shad Alosa immaculata (Bennet, 1835) in the Bulgarian sector of the Danube River are studied. The catchments have been done in April 2010 and April 2012 during the spawning migration of the species. Altogether 239 specimens have been examined. The age of the individuals varied between II and V. The most abundant are II and III age groups representing 53.2% and 37.9% of the spawning part of the population respectively. The standard length ranged from 15.4 cm to 37 cm and the weight ranged from 37 g to 351 g. The equation representing the relation between the standard length and the scale radius in the population is L = 0.3955S – 0.996; r = 0.8. The length – weight relationship is described by the equation W = 0.0234L2.7315, r = 0.95. The von Bertalanffy`s length and weight growth equations are Lt = 35.749 [1 – e-0.493209 (t-0.34115)] and Wt = 436.228 [1 – e-0.319987 (t – 1.04376)]2.7315 respectively.

Key words: Pontic shad, Alosa immaculata, Danube River, age, growth
Abbreviations: NAFA – National Agency of Fisheries and aquaculture

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