engleski

The growth of five populations of chub (Leuciscus cephalus) in the Danube river basin of Croatia

Data on chub growth in Croatia was collected from five locations: the Bednja river, the Lika river, middle section of the Dobra river and the upper sections of the Lonja and Kupa rivers. In every source of the data the age was determined on the number of year rings formed on the scales and the length was presented as the mean sizes in different age-groups. The growth of chub during the first eight years of its life was the lowest in the upper Kupa river and the Lika river. Both rivers are situated in the mountainous part of Croatia where climate is less than moderate and vegetation period is shorter. The water is clean and the amount of nutrients is low. However, the chub of the upper Kupa river expressed positive allometric growth, due to the higher amount of invertebrates. The Dobra river is situated in the same part of the country, but in this analysis the middle section was used. The climate is milder there, water quality is still good and chub expressed very balanced growth in both - length and mass. The remaining two rivers, the Bednja and the Lonja, are situated in the Croatian portion of Pannonian valley, where the climate is warmer, vegetation period longer and the water usually reacher in nutrients. The phi-primes of Croatian chub varies between 5,49 and 5,90. This values are similar to the one calculated from the British data (5,90).

growth; populations; chub; Leuciscus cephalus; Danube; Croatia

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