Integrated cage-pond carp farming for increased aquaculture production
The study investigated the potential for increasing carp (Cyprinus carpio L.) production in temperate climates without expanding farming area and simultaneously reducing wastewater discharge in intensive fish production using an in-pond cage system. An earthen pond with a stocking density of 209.3 kg per ha-1 and four cages stocked with 8.12 kg m-2 (A1 and A2) and 2.61 kgm-2 (B1 and B2) were monitored. The gross yield from the cages was 27.09 kgm-2 (A1), 24.3 kgm-2 (A2), 10.09 kgm-2 (B1), and 9.73 kgm-2 (B2). The fish in the pond had the highest specific growth rate (SGR) at 0.98%, and the feed conversion ratio (FCR) was above 3 for all the cages. The cages provided a high enough nutrient load to enable a net fish production of about 450 kg ha-1 in the pond. Ineffective feed utilization affected the production performance in the cages. Thanks to the high yield obtained in the pond, the overall return on the investment was 16%, which rendered production profitable.