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Life history Broodstock –Spawning and care –Fertilization methods Egg development and hatching –Stages of development –Methods of incubation Fry rearing.

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Presentation on theme: "Life history Broodstock –Spawning and care –Fertilization methods Egg development and hatching –Stages of development –Methods of incubation Fry rearing."— Presentation transcript:

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 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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