Research Highlights - ARS Aquaculture Systems Research Unit

Aquaculture/Fisheries Center Research Highlights

ARS Aquaculture Systems Research Unit

Use of Threadfin Shad as a Forage Fish in Catfish Production Ponds
Bart Green

A pond study was conducted to determine if channel catfish feeding frequency could be reduced to once every three days compared to daily in ponds co-stocked with threadfin shad. Catfish in multiple-batch culture were fed daily or every third day with 32% protein feed. Ponds within each feeding rate were stocked with threadfin shad. Stocking shad did not substitute for feeding. Feeding catfish every third day resulted in 67% less stocker yield, 62% less feed used, 43% smaller fish, 88% of stockers weighing less than 1.5 lb/fish at harvest, and all with an FCR similar to that for catfish fed on a daily basis.
Growth of Stocker Channel Catfish at Three Stocking Rates
Bart Green and Carole Engle

Stocker channel catfish (0.53 lb) were stocked at 3,500, 4,500, or 5,500/acre in single-batch culture for a 163-d production cycle. Net yield of catfish increased linearly with increased stocking rate, while mean size at harvest decreased linearly with stocking rate. Fish average weight ranged from 1.6-2.2 lb at harvest. At harvest, 8% of the population was less than 1.5 lb/fish for the low stocking rate, and 21% of fish weighed less than 1.5 lb/fish for the high stocking rate.
Amending Freshwater for Production of Litopenaeus vannamei in Earthen Ponds
Bart Green

A study was conducted to determine whether freshwater could be amended with key ions to permit successful culture of Pacific white shrimp (Litopenaeus vannamei) and to determine whether stocking a PL25 shrimp compared to a PL 15 shrimp would permit two crops per growing season. Freshwater can be amended with Na, Cl, K, Mg, and SO4 to culture Pacific white shrimp successfully. However, stocking PL25 shrimp fails to yield two marketable crops during the May-September growing season. Ponds stocked with PL15 shrimp had a mean gross yield of 3,449 kg/ha after 125 d of culture. At harvest, shrimp averaged 19.3 g/shrimp. The first crop of PL25 shrimp, harvested after 55 d, yielded a mean of 976 kg/ha of 5.5-g average weight shrimp. The second crop of PL25 shrimp yielded a mean of 2,463 kg/ha after 63 d of culture. Shrimp averaged 9.0 g/shrimp. For the season, the total yield from ponds stocked with PL25 shrimp averaged 3,419 kg/ha. Stocking PL25 shrimp does not appear to be an economically viable strategy.