Freshwater Prawns in Georgia

1. Freshwater Prawns in Georgia Gary J. Burtle Animal & Dairy Science The University of Georgia

2. Freshwater Prawns • Machrobrachium rosenbergii • An exotic shrimp from Malaysia • Tropical • Lives in freshwater for part of its life-cycle

3. U. S. Prawn Culture • Of interest for over 25 years. • Limited by the availability of seed stock. • Cultured in Texas, Kentucky, Mississippi, South Carolina, recently in Georgia. • Average production 500 to 800 pounds per acre. • Maximum production about 2,500 lb/A with structure and higher stocking densities.

4. Reasons for Caution when Considering Prawn Production • More difficult to raise than catfish • High prices are a temporary effect of a niche market • Product quality is unique to freshwater prawns • Tail is only 40% of total weight • Juveniles are very expensive

5. Prawn Production in Ponds • Prepare pond for stocking (early April in Georgia) • Stock 10,000 to 30,000 juveniles per acre • Fertilize for first 30 days • Feed a sinking feed during months 2-4 • Monitor and control oxygen and pH • Use narrow ponds less than 2 acres in size • Harvest before water falls below 60 degrees

6. Preparing Ponds for Stocking Prawns • Drain, dry, disinfect • Fill quickly within 14 days of stocking • Fill with filtered pond water if possible • When using well water, be certain of zooplankton abundance before stocking • Stock grass carp for weed control (20 or more per acre) • Install structure (horizontal is better than vertical placement)

7. Prawn Pond with Structure

8. Proper Sized Juvenile Prawns • 60 day old, 95/oz • 28-35 day old, 250 to 280 per oz • Uniform size very important • Careful handling and stocking are essential to juvenile survival • Avoid overcrowding

9. Feeding Prawns • Start with cottonseed meal and N-P-K • Use sinking catfish feed for 500 to 800 lb/A • Use shrimp diet for possibly higher yields • Monitor zooplankton with net during first month • Feed over entire pond area • Estimate feed rate based on prawn samples

10. Water Quality in Prawn Ponds • Aerate continuously. • Keep oxygen above 3.0 ppm. • Monitor pH twice each day. • Flush with water to keep below 9.0. • Possibly add gypsum to lower pH (1,000 to 2,000 pounds per acre added as needed). • Keep water deeper than 3 ft to prevent wading bird predation.

11. Prawn Harvesting

12. Harvest Procedure • Seine most of prawns with water at 1/2 depth • Use 1/2 inch mesh seine, grade with bar grader (63/64 inch spacing) • Consider partial harvest one month before end of season • Final harvest requires pond draining

13. Prawn Marketing • Entirely up the the individual producer • Local sales of fresh prawn limits the volume of the market in Georgia • Rural locations will usually get lower prices than urban areas • Entire harvest must be sold within a few days • Removing heads constitutes processing

14. Economic Sketch • Breakeven at 1,000 lb/A is about $5.00 per pound • Juveniles cost $1,500 to $3,000 per acre • Feed costs $300 to $550 per acre • Aeration costs $200 to $400 per acre • Labor cost $800 to $1,200 per acre • Variable cost total$2,800 to $5,100 per acre