General Concepts in Fish Reproduction

1
General Concepts in Fish Reproduction
2
General Considerations

• Natural habitat of species
• Body size and first parity
• Annual vs. multiple spawning
• Eggs are hardest to produce
• Hormone treatments

3
Reproductive Strategies

• Maximize survival of eggs and fry
• natural habitat vs. man-made
• Ultimate Factors
• food supply
• absence of predators
• water quality

4
Reproductive Strategies

• Ultimate Factors
• Proximate Factors
• environmental cues
• anticipate future spawning

5
Day Length and Temperature
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Reproductive Strategies

• Synchronous
• All eggs are spawned and the fish dies
• (What fish have we seen that fits this?)

7
Reproductive Strategies

• Synchronous
• All eggs are spawned and the fish dies
• Group Synchronous
• Multiple spawning and seasonal spawners
• (Any examples?)

8
Reproductive Strategies

• Synchronous
• All eggs are spawned and the fish dies
• Group Synchronous
• Multiple spawning and seasonal spawners
• Asynchronous
• Multiple and daily spawning
• All oocyte development stages present

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Stages of Reproduction

• Stage 1 Oocyte development
• Gonadotropin independent
• Body size dependent

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Stages of Reproduction

• Stage 1 Oocyte development
• Stage 2 Vitellogenesis
• Egg yolk production
• High nutritional demand
• Longest phase

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Stages of Reproduction

• Stage 1 Oocyte development
• Stage 2 Vitellogenesis
• Stage 3 Oocyte maturation
• Germinal vesicle migration
• Resumption of meiosis
• Water uptake

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Stages of Reproduction

• Stage 1 Oocyte development
• Stage 2 Vitellogenesis
• Stage 3 Oocyte maturation
• Stage 4 Spawning
• Optimum environment
• Mating behaviors

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Stages of Reproduction

• Stage 1 Oocyte development
• Stage 2 Vitellogenesis
• Stage 3 Oocyte maturation
• Stage 4 Spawning
• Stage 5 Recovery
• Restore body condition
• New oocyte development

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Stages of Reproduction

• Stage 1 Oocyte development
• Stage 2 Vitellogenesis
• Stage 3 Oocyte maturation
• Stage 4 Spawning
• Stage 5 Recovery

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Spawning

• Release of eggs and milt
• Fertilization
• Simulate natural environment
• Dry stripping
• Hormone induction

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Spawning

• Simulate natural environment
• Milk cans
• Ammo boxes
• Floating nests
• Fiber mats

17
Spawning

• Dry Stripping
• Express eggs and milt
• Mix together
• Add water
• Activate eggs and milt
• closure of micropyle
• Silting
• MS222 is toxic to eggs and milt!

18
Spawning

• Induced Spawning
• Stage 3 Oocyte maturation
• Egg Sampling
• Egg size
• Yolk clarity
• Oil globules

19
Spawning

• Hormone Injection
• Carp Pituitary Extract
• Human Chorionic Gonadotropin
• Single or multiple injection
• Stage 3 complete in 12 - 48 h
• Natural Environment or Dry Stripping

20
Conclusions

• Reproductive strategies are variable
• Aquaculturist provides proximate and ultimate
  factors
• Early stages critical for egg viability
• Hormone treatments induce egg maturation