an enterprise using ponds both for raising fish and for fattening ducks. The leading sector on a fish-and-duck farm is fish raising. The ranging of ducks is possible only if certain established rules and standards are observed.
Ducks fertilize the ponds with their droppings, thereby increasing the natural feed base for the fish (zooplankton and midge larvae). They improve the pond by loosening the bottom and eating surface and underwater vegetation. They also destroy fish pests and competitors for food. The ducks feed on mollusks, insect larvae, tadpoles, and small frogs—animals that the carp (the principal fish raised in ponds) virtually does not use. The ducks also destroy rough fish, thereby raising the natural fish productivity of the ponds by an average of 40 percent. In addition, ducks kept in fish ponds grow more rapidly than other ducks, consuming almost 1½ times less concentrated feed per unit of weight increase. The lower feed requirements reduce the cost of duck meat by 15–20 percent.
Duck raising is advisable only on ponds having a density of 200–250 ducklings per hectare of water surface for standing ponds or 500–600 ducklings per hectare for flowing ponds. The year-old carp are released in the ponds 15 to 20 days before the ponds are stocked with ducks. Ducks and carp can also be raised together in bogs.
Fish-and-duck farms have been developed in many European countries, including Hungary, the German Democratic Republic, and Czechoslovakia.
REFERENCESCherfas, B. I., and G. A. Zernyshko. Vygul utok v karpovykh prudovykh khoziaistvakh. Moscow, 1946.
Shpet, G. I., and N. I. Kharitonova. “Vliianie vygula utok na povyshenie ryboproduktivnosti krupnykh karpovykh prudov.” Rybnoe khoziaistvo, issue 2, 1965.
A. S. VAVILKIN