life history broodstock –spawning and care –fertilization methods egg development and hatching...

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

• In nature may grow in excess of 20kg• Average size used in culture?

– 0.9 – 4.5 Kg» »

Channel Catfish

• Spawning– Late spring and summer– Manipulation of spawning time

••

– Sorting of sexes (Often difficult)During spawning

– Female – – Male –

»

Channel Catfish

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

• •

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

Channel Catfish

• Pen spawning– Used at some operations– Advantages

• • • removal of fish after spawning•

– Success is dependant on ability to select fish

Channel Catfish

• Aquarium/tank spawning– Provides greatest degree of control

• •

– Hormones required •

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%)

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•

Tilapia

• Almost all mouthbreeders– – –

• Advantages– multiple spawnings–

• Disadvantages– – female has reduced growth – reproduction

energy

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

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

Trout and Salmon

• Spawning methods– Air Spawning

• • 18 g needle and compressor•

–

Trout and Salmon

• Egg quality/ripeness– Check fish prior to spawning

• • Feel for “free” or loose eggs

– limit water, feces, dirt, or debris•

Trout and Salmon

• Fertilization methods– Dry method

• In container – ovarian fluid passes through: collected for virology

• – Wet method

• • Fertilization rates are usually lower

Trout and Salmon

• Fertilization methods– Delayed fertilization

• 4-6 females spawned• milt from multiple males

–

• “broken eggs”•

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•

Trout and Salmon

• Egg stages– Sensitive stage “Green eggs”

• •

– Eyed stage• Eyes visible to hatching• “shocking” occurs –

• • count (% eyed/fertilized)• • disease certifications

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• •

Trout and Salmon

• Egg disinfection– When received from other facilities

or at water hardening– – – Do not treat within 5 days of hatch

Trout and Salmon

• Egg transportation – transport female prior to spawning –

• • Should use extender

– after WH stage – –

• Best survival•