WARM-FRESHWATER AQUACROPS [objectives]

1. WARM-FRESHWATER AQUACROPS[objectives] • Describe general environmental requirements for warm-freshwater species • Discuss the production of catfish, crawfish, prawns, tilapia, striped bass, and other finfish species

2. GENERAL REQUIREMENTS FOR WARM-FRESHWATER SPECIES • Temperature range of 70o to 90o F. • Species grown in tanks in greenhouses where the water can be kept warm year-round are not affected by seasonal changes

3. PRINCIPLES OF SPECIES SELECTION • Select only a species adapted to the production system to be used. • Bryant HS already had greenhouses before we decided to grow redclaw crawfish • Therefore we could control both the air and water temperatures to grow this tropical species year-round

4. CATFISH • Catfish production leads all freshwater aquacrop production in the U.S. • Predominant species are the channel catfish, blue catfish, and white catfish • Genetically improved and hybrid catfish are increasingly being grown

5. CHANNEL CATFISH

6. BLUE CATFISH

7. WHITE CATFISH

8. HYBRID CATFISH

9. ENVIRONMENT REQUIRED • Optimum temperature 75 – 85o F • Stop feeding when temperature is above 95o F or below 60o F • Will grow in ponds, streams, raceways, or other water facilities • Dissolved oxygen kept above 4 mg/L • pH range 6.3 – 7.5

10. SEEDSTOCK • Natural spawning – cavity spawners; lay eggs in hollow logs and stumps • Farm spawning – use spawning containers such as milk cans, boxes, etc.

11. SEEDSTOCK • Hatching – either hatch naturally or in hatchery • Needs moving water (not flowing) at temperature of 75 – 85o F • Hatching occurs in 6 – 10 days • Newly-hatched fry live off egg sac for several days • Fine meal feed is used for next several weeks

12. HATCHING CATFISH

13. CULTURE, STOCKING, AND FEEDING CATFISH • Stocked as 5 – 8-inch fingerlings • Stocking rates vary from 2000 – 5000 per acre • Typically fed floating feed that is 28 to 32% protein • Should be fed 1 – 2 times daily • Fingerlings are fed 10% of body weight daily, fish under one pound need 3% daily, and fish over one pound need 2% daily

14. STOCKING AND FEEDING

15. HARVESTING CATFISH

16. MARKETING CATFISH • Broodfish may be sold to hatchery operators • Hatcheries produce eggs, fry, and fingerlings • Grow-out farmers stock ponds with fingerlings and grow them as food • Recreational fee-lake operators buy from growers to stock out their ponds

17. CRAWFISH

18. ANATOMY

19. MOLTING (ECDYSIS) • Crawfish have hard shell which must be shed to grow • Calcium is extracted from shell and stored in glands while molting • After shedding old shell, body uptakes water and expands 20% • New shell hardens within 12 hours • Crawfish molts about 12 times before it reaches maturity

20. MOLTING

21. REQUIRED ENVIRONMENT • Naturally found in shallow, weedy swamps and ponds • Prefer water temps between 65 to 85oF • Dormant below 45oF • Range of pH 5.8 to 8.2 • Redclaw are tropical and die at temps below 50oF

22. CRAWFISH PONDS

23. SEEDSTOCK • Burrowing – crawfish dig holes (burrows) for shelter and reproduction • Mating – male deposits sperm packet on female in late spring (redclaws can mate up to 3 times annually) • Hatching – eggs (200 – 800) are attached to underside of abdomen and hatch in 14 – 21 days (30 – 40 days for redclaw)

24. GRAVID RED SWAMP CRAWFISH

25. GRAVID REDCLAW

26. FEEDING • Crawfish are omnivorous and feed mainly on detritus (decaying bits of plants and animals) • Red swamp crawfish forage on rice stubble • Commercial crawfish feeds are often used as supplemental feed

27. DISEASES AND PREDATORS • Very few diseases cause problems with crawfish (bacterial and fungal) • Crawfish can be infested with zebra mussels • Common predators are trash fish, birds, raccoons, frogs, snakes, turtles, and water beetles

28. DISEASES AND PREDATORS

29. HARVESTING AND MARKETING • Red swamps are harvested in winter and spring with baited traps • Crawfish are sold alive for boiling or tails may be peeled and frozen • New market niches are developing for softshell crawfish

30. HARVESTING AND MARKETING

31. FRESHWATER PRAWNS River prawn Macrobrachium rosenbergii Tiger prawn Panaeus esculentaus Pacific white shrimp Panaeus vannemai Grown in low salinity water (<5 ppt) Water temps 75 to 85oF Grown in earthen ponds outdoors and lined ponds in greenhouses

32. Macrobrachium Tiger prawn Shrimp farm Pacific white shrimp

33. SEEDSTOCK • Females produce about 28,000 eggs per ounce • Eggs hatch in 20-21 days and must be fed plankton • Larvae swim upside down and backwards • Reach postlarvae stage (stocking size) in 15 to 45 days

34. Nauplius Zoea Mysis

35. TILAPIA • Most widely raised warm-freshwater fish in the world • Tilapia first cultured 4000 years ago in Africa • Most common species cultured include Java, Zanzibar, blue, and Nile tilapia (all four are mouth-brooders)

36. Java Zanzibar Nile Blue

37. CULTURE • Tilapia are tropical and must be kept above 50oF (80 to 90oF is ideal) • Tolerate low oxygen, high ammonia, and other conditions that would be lethal to many species of fish. • Spawning is easy; the problem is usually overpopulation • Tilapia naturally feed on plants, insects, detritus, and plankton

38. STRIPED BASS

39. CULTURE • Can grow in freshwater, brackish water, or saltwater (most commercial production in freshwater) • Grow best at 77 to 88oF (survive down to 40oF) • Specialized hatcheries needed for seedstock production • Stocked 1000 to 4000 per acre • Need feed 35 to 45% protein

40. OTHER FINFISH bluegill redear warmouth