Abstract
Impact of carp stocking on species diversity, yield and recruitment of non-stocked indigenous fish species (NIFS) in two series of oxbow lakes under carp fingerling stocking-induced aquaculture with a series of control sites in southwest Bangladesh is documented. Fishers' catch analyses, active sampling, spawning observation and maturation study made the data base. The study reveals a negative impact of multiple stocking of carp at relatively high stocking density and no virtual impact for moderate stocking on the target species. The investigation results altogether 81 freshwater fish species representing 12 orders, 27 families and 50 genera under Osteichthyes class over all the control and culture series lakes. The study also records 6 prawn species. The systematic position and nomenclature including scientific, local (Bangla) and comprehensive English names are furnished. In addition, the endeavour reveals a cyprinoid barb, Puntius parrah Day (1865): Cyprinidae and a centropomid glass perch, Parambassis thomasi (Day, 1870): Centropomidae as their new ranges of distribution. to Bangladesh. The study records 8 exotic fish species in the studied lakes including alien species intrusion of two freshwater fish species (Oreochromis niloticus and Hypophthalmichthys molitrix) in the control sites. The study estimates mean annual catch and yield of the lakes through systematic catch analyses of the commercial fishers over a period of 26 months. The study estimates mean annual yield as 809 kg/ha in series 1 (776 kg/ha in Bukbhara and 1010 kg/ha in Kannyadaha), 1747 kg/ha in series 2 (2041 kg/ha in Nasti and 1114 kg/ha in Marufdia) while 696 kg/ha in control series (625 kg/ha in Rajganj and 825 kg/ha in Kapotakkhya). The study monitors selected maturity parameters and corresponding reproductive indices with somatic condition index of ten representative NIFS on recruitment. The study reviews present status of oxbow lake aquaculture in Bangladesh. New terms, tools, techniques and ideas are incorporated. Trophic levels of fish in oxbow lakes are projected through trophic level concept of Lindeman (1942) with new fish groupings. The study also points out tips for the sustainable management of non-stocked indigenous fish species (NIFS) in Bangladesh.