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Life history

Life history. Broodstock Spawning and care Fertilization methods Egg development and hatching Stages of development Methods of incubation Fry rearing Fingerling stage Growout stage Harvest, transport and processing. Life history considerations . Channel Catfish Broodfish

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Life history

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  1. Life history • Broodstock • Spawning and care • Fertilization methods • Egg development and hatching • Stages of development • Methods of incubation • Fry rearing • Fingerling stage • Growout stage • Harvest, transport and processing

  2. Life history considerations • Channel Catfish • Broodfish • In nature may grow in excess of 20kg • Average size used in culture? • 0.9 – 4.5 Kg

  3. Channel Catfish • Spawning • Late spring and summer • Manipulation of spawning time • Sorting of sexes (Often difficult) During spawning • Female – • Male –

  4. Channel Catfish • Use of Hormones • May use before putting in pond or pens • Human chorionic gonadotropin • Acetone-dried carp pituitary

  5. Channel Catfish • Pond spawning (natural) • Must provide nest (Container) • Broodfish • 60-375 fish/hectare • Eggs (2 options) • Leave to hatch (male guards nest) • Nests • Inspect about 3X/wk

  6. Channel Catfish • Pen spawning • Used at some operations • Advantages • removal of fish after spawning • Success is dependant on ability to select fish

  7. Channel Catfish • Aquarium/tank spawning • Provides greatest degree of control • Hormones required

  8. Channel Catfish • Egg development and hatching • 5 to 10 days (optimum temp. – 26C) • Deposited as an adhesive mass • If removed to hatchery • Hatch in trough (aeration – paddle wheel) • Hatching jars - • survival rates (80-90%)

  9. Channel Catfish • Fry stocking (yolk sac absorbed at about 1 wk) • Treat ponds before stocking • If fry hatched in troughs • Move to raceway or pond • Grow to harvest

  10. Tilapia • Almost all mouthbreeders • Advantages • multiple spawnings • Disadvantages • female has reduced growth – reproduction energy

  11. Trout and Salmon • Broodfish • Quality • 3-5 yrs (commercial production) • 2 yrs – small eggs in most cases – low fertilization rates: may strip eggs and return to growth cycle • If wild caught or captured (dictates size) • Separate male and females • Males are more aggressive

  12. Trout and Salmon • Spawning methods • Handstripping • Expel eggs by pressure to abdomen • Abdominal incision • Fish Killed • Belly opened over container • Remaining eggs are shaken loose

  13. Trout and Salmon • Spawning methods • Air Spawning • 18 g needle and compressor

  14. Trout and Salmon • Egg quality/ripeness • Check fish prior to spawning • Feel for “free” or loose eggs • limit water, feces, dirt, or debris

  15. Trout and Salmon • Fertilization methods • Dry method • In container – ovarian fluid passes through: collected for virology • Wet method • Fertilization rates are usually lower

  16. Trout and Salmon • Fertilization methods • Delayed fertilization • 4-6 females spawned • milt from multiple males • “broken eggs”

  17. Trout and Salmon • Egg stages • Water hardening • increase uptake as egg contacts FW • Disinfection can be done – decrease vertical transmission risks • Can be done in bucket, trays, or incubator

  18. Trout and Salmon • Egg stages • Sensitive stage “Green eggs” • Eyed stage • Eyes visible to hatching • “shocking” occurs – • count (% eyed/fertilized) • disease certifications

  19. Trout and Salmon • Enumeration and sorting • Weight method • 100 egg sample – get average weight • Drain water off eggs – lot wt. • Displacement method • 50 eggs • calculate # eggs/volume of water displaced • Mechanical method

  20. Trout and Salmon • Egg disinfection • When received from other facilities or at water hardening • Do not treat within 5 days of hatch

  21. Trout and Salmon • Egg transportation • transport female prior to spawning • Should use extender • after WH stage – • Best survival

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