Impact of stocking common carp (Cyprinus carpio) on production in some selected beels in Gazipur district, Bangladesh

The present study was conducted in three seasonal beels in Gacha union under Gazipur sadar upazila in Gazipur district during the period from June 2015 to January 2016. The objectives of the study were to evaluate the impact of stocking common carp on the abundance and biodiversity of native fish species in seasonal beels. Three seasonal beels such as Baroholai, Makhna and Buridha which were connected with Turag River through different canals were selected to implement the study. Baroholai and Makhna beel were stocked with common carp fingerlings at 2500 per hectare. Buridha beel served as control. Necessary data were collected from the fishermen and lease holders of the concern beel through using structured questionnaire by survey method. A total of 42-43 species of fishes were recorded from stocked beel as against of 43 species in control beel. Shanon- Weiner diversity index averaged 2.58 in stocked beel as opposed to 2.68 for control beel. The studied beel had medium richness in terms of biodiversity and faunal abundances. Per hectare fish production was 522-577kg in stocked beels as compared to 365kg in control beel. Cyprinidae was the most abundant group contributing to the bulk of fishery yield. Surface feeder took a lead over other groups of fishes in stocked beel as opposed to bottom feeder in case of control beel. Bottom dwelling small catfishes seems to be affected in presence of common carp in the stocked beels. Control beel harboured increased number and quantity of catfishes. Fish productions in the seasonal beels were profitable. Per hectare total cost of fish production averaged tk 34976.67 as against of total gross return of tk 92683.67. Benefit cost ratio (BCR) was found to be 2.57-3.42 in stocked beel and 2.01 in control beel. Further researches are needed to precisely determine the possible consequences of stocking common carp in seasonal beels.