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• The relationship between silver crucian carp (Carassius auratus gibelio bloch) and fish poulations of natural waters

  30-36

  Péter Bársony

  Csaba Vinginder

  Views:

  136

  The fisheries management on inland waters is very complicated. Often the unclear propriety rights make the normal management difficult, and other times the stocking of the waters is problematic. In the last hundred years a lot of new fish species have been introduced to Hungary. Lot of them have found their place in the Hungarian fishfauna, till others have caused big problems for the fish farmers, and the anglers too. The biggest problem was caused by the topmouth gudgeon (Pseudorasbora parva Schlegel, 1842) brown bullhead (Ictalurus nebulosus LeSueur, 1819) and the silver crucian carp (Carassius auratus gibelio Bloch, 1782). In this article I show what kind of problems were caused by the silver crucian carp, because it seems that this fish is the most harmful.The damage caused by silver crucian carpposesa complex question. To get into the ponds and rivers, the crucian carps occupy the territory form the native fishspeciesandthesilvercrucian carp competes with these fishes for food, too.The silver crucian carphasa special reproduction method and because of this the speciesis expand rapidly. The silver crucian carp is able to reproduce with other cyprinids, and because the female silver crucian carps are triploids every fingerlings will be silver crucian carp.This fish is a vectorfora lot of diseases, which can easily spread over for other species.

• The effect of silver crucian carp (Carassius auratus gibelio Bloch) on the yields and the production value of common carp (Cyprius carpio) fingerlings

  5-10

  Péter Bársony

  László Pócsi

  András Szabó

  Views:

  114

  During the last few years, the spread of the silver crucian carp has caused significant problems in pond fish culture. One of the main challenges of successful fish production in fishponds, is to rid ponds of the silver crucian carp. The nature of the damage caused by silver crucian carp is a complex question. To get into the ponds, the crucian carps occupy the territory before the common carp, and competes for food with common carp. The silver crucian carp has a less favorable food coefficient than the common carp, and it’s value is also lower. Therefore, the income of the fish farm decreases. In the course of the experiment, carp fry were stocked in 5 nursing ponds at the same stocking rate, with different (0,- 50-, 100-, 150-, 200%) stocking rates of silver crucian carp fry, respectively. At the end of the experiment, the yield/hectar and the production values were calculated. The experiment proved that the presence of the silver crucian carp in the fishponds causes lower yields and production values.

• Study of the Interaction Between Common Carp (Cyprinus carpio) and Silver Crucian Carp (Carassius auratus gibelio Bloch)

  9-12

  Péter Bársony

  László Pócsi

  András Szabó

  Views:

  132

  Some of the main questions in the fish farming are the good manuring and the success of the feeding. For the best result is very important that only those fishes take place in the fishponds what we want. It seems to be easy but difficult to do. One of the main challenges of the successful fish production in fishponds, is to rid ponds of the silver crucian carp. In the course of the experiment, carp fry were stocked in 5 nursing ponds at the same stocking rate, with different (0-, 50-, 100-, 150-, 200%) stocking rates of silver crucian carp fry, respectively. During the rearing season, weekly test fishings were made to control the growth of the fishes. At the end of the experiment, the yield/hectar and the growth rates were calculated. The experiment proved that the presence of the silver crucian carp in the fishponds causes lower growth rates and productivity in common carp. In the control pond (without silver crucian carp), the average weight of the common carp was 25 g and the yield/hectar was over 900 kg, while in the pond with the most silver crucian carp, the average weight of the common carp was 9 g and the yield/hectar was only 158 kg.

• Study of the Interaction Between Common Carp (Cyprinus carpio L.) and Silver Crucian Carp (Carassius auratus gibelio B.)

  16-19

  Péter Bársony

  László Pócsi

  András Szabó

  Views:

  141

  During the last few years, the spread of the silver crucian carp caused significant problems in pond fish culture. One of the main challenges of the successful fish production in fishponds, is to rid ponds of the silver crucian carp. In the course of the experiment, carp fry were stocked in 5 nursing ponds at the same stocking rate, with different (0-, 50-, 100-, 150-, 200%) stocking rates of silver crucian carp fry, respectively. During the breeding season, weekly test fishings were made to examine the growth of the fishes. At the end of the experiment, the yield/hectar and the growth rates were calculated. The experiment proved that the presence of the silver crucian carp in the fishponds causes lower productivity and growth rates in common carp. In the control pond (with no silver crucian carp), the average weight of the common carp was over 20 g and the yield/hectar was over 700 kg, while in the pond with the most silver crucian carp, the average weight of the common carp was 4.5 g and the yield/hectar was only 123 kg.