Growth, yield, dressout, and net returns of bighead carp Hypophthalmichthys nobilis stocked at three densities in fertilized earthen ponds

Bighead carp Hypophthalmichthys nobilis have been raised in the United Stat es for two decades and sold through the livehaul market, but their profitab ility in monoculture has not been evaluated. Three studies were conducted i n 0.10-ha earthen ponds to evaluate the effect of bighead carp stocking den sity on growth, yield, dressout yield, and net returns. Initially, bighead carp (average weight of 0.36 kg) were stocked at rates of 500, 320, or 130 fish/ha with three replicates of each treatment. Stocking rates for 2-yr-ol d fish (average weight of 2.45 kg) were reduced to 320, 220, or 130 fish/ha in the second year. Net yields of bighead carp stocked at 500 fish/ha (963 kg/ha) were significantly higher (P < 0.05) than net yields at the 320 fis h/ha density (771 kg/ha), and these were significantly greater (P < 0.05) t han net yields at 130 fish/ha (369 kg/ha) in the first growing season. Net yields in the second growing season were not significantly different (P > 0 .05) among densities. There were no significant differences (P > 0.05) amon g treatments in yearly growth which ranged from 11-17 g/d in the first and from 6-13 gld in the second growing season. Dressout percentages for whole- dressed, steak, shank fillet, and shank fillets with white meat only did no t differ with stocking density (P > 0.05). Enterprise and partial budget an alysis indicated that monoculture of bighead carp in fertilized ponds is pr ofitable only in the short run at average livehaul market prices, because r evenues exceeded variable but not fixed costs. The negative net returns, wh en all costs were accounted for, indicated that it is not profitable to con struct ponds solely for monoculture of bighead carp.