The length-mass relationship of chub in five Croatian rivers was investigated. According to that relationship the rivers were divided into three groups. During their first years in the warm rivers of the Pannonian valley (Lonja and Bednja), the chub have high condition factor which comes down to an average (1.21+0.10 and 1.29+0.10) when the entire life is taken into consideration. For that reason its allometric factor b is lower than 3 (2.875 and 2.872). Long vegetation period of these rivers ensures the best CF as well as the best growth in length.
The chub from the Kupa and Dobra rivers that flow down the mountain slopes, were slower in growth up to the fourth year, when they reached CF around 1.2. Likewise, their average values of condition factor were 1.10ą0.10 and 1.08+0.17 and their allometric b factor was higher than 3 (3.240 and 3.369 respectively).
The worst conditions for both - length and mass growth of chub were in the river Lika. Being cooler and oligotrophic mountainous river, the average CF value was 0.99+0.08 and b factor was 2.670.
The length-mass relationship of the five chub populations investigated are a precise reflection of the overall environmental conditions of the rivers they inhabit.

growth; chub; length-mass relationship; Leuciscus; Croatia

Published by University of Zagreb, Faculty of Agriculture, Zagreb, CROATIA
Sponsored by Ministry Science and Education of the Republic of Croatia