General Concepts in Fish Reproduction Christopher A. Bidwell Department of Animal Sciences Purdue University.

General Concepts in Fish General Concepts in Fish ReproductionReproduction

Christopher A. BidwellChristopher A. Bidwell

Department of Animal SciencesDepartment of Animal Sciences

Purdue UniversityPurdue University

General ConsiderationsGeneral Considerations

• Natural habitat of speciesNatural habitat of species

• Body size and first parityBody size and first parity

• Annual vs. multiple spawningAnnual vs. multiple spawning

• Eggs are hardest to produce Eggs are hardest to produce

• Hormone treatmentsHormone treatments

Reproductive StrategiesReproductive Strategies

• Maximize survival of eggs and fryMaximize survival of eggs and fry- natural habitat- natural habitat

• Ultimate FactorsUltimate Factors- food supply- food supply- absence of predators - absence of predators - water quality- water quality

Reproductive StrategiesReproductive Strategies

• Ultimate FactorsUltimate Factors

• Proximate FactorsProximate Factors

- environmental cues- environmental cues

- anticipate future spawning- anticipate future spawning

Day Length and Day Length and TemperatureTemperature

-5

0

5

10

15

20

25

1-May

1-Jun

1-Jul 1-Aug

1-Sep

1-Oct

1-Nov

1-Dec

1-Jan

1-Feb

1-Mar

1-Apr

Water Temperature (C)

Day Length (h)

Reproductive StrategiesReproductive Strategies

Synchronous Synchronous – All eggs are spawned and the fish diesAll eggs are spawned and the fish dies

Reproductive StrategiesReproductive Strategies

Synchronous Synchronous – All eggs are spawned and the fish diesAll eggs are spawned and the fish dies

Group Synchronous Group Synchronous –Multiple spawning and seasonal spawnersMultiple spawning and seasonal spawners

Reproductive StrategiesReproductive Strategies

Synchronous Synchronous – All eggs are spawned and the fish diesAll eggs are spawned and the fish dies

Group Synchronous Group Synchronous – Multiple spawning and seasonal spawnersMultiple spawning and seasonal spawners

AsynchronousAsynchronous– Multiple and daily spawningMultiple and daily spawning

– All oocyte development stages presentAll oocyte development stages present

Stages of ReproductionStages of Reproduction

• Stage 1Stage 1 Oocyte (immature egg) Oocyte (immature egg) development development

- Gonadotropin independent- Gonadotropin independent

- Body size dependent- Body size dependent

Stages of ReproductionStages of Reproduction

• Stage 1Stage 1 Oocyte developmentOocyte development

• Stage 2Stage 2 Vitellogenesis Vitellogenesis

- Egg yolk production- Egg yolk production

- High nutritional demand- High nutritional demand

- Longest phase- Longest phase

Stages of ReproductionStages of Reproduction

• Stage 1Stage 1 Oocyte developmentOocyte development

• Stage 2Stage 2 VitellogenesisVitellogenesis

• Stage 3Stage 3 Oocyte maturationOocyte maturation

- Germinal vesicle (nucleus) migration- Germinal vesicle (nucleus) migration

- Resumption of meiosis (cell division)- Resumption of meiosis (cell division)

- Water uptake- Water uptake

Stages of ReproductionStages of Reproduction

• Stage 1Stage 1 Oocyte developmentOocyte development

• Stage 2Stage 2 VitellogenesisVitellogenesis

• Stage 3Stage 3 Oocyte maturationOocyte maturation

• Stage 4Stage 4 SpawningSpawning

- Optimum environment- Optimum environment

- Mating behaviors- Mating behaviors

Stages of ReproductionStages of Reproduction

• Stage 1Stage 1 Oocyte developmentOocyte development

• Stage 2Stage 2 VitellogenesisVitellogenesis

• Stage 3Stage 3 Oocyte maturationOocyte maturation

• Stage 4Stage 4 SpawningSpawning

• Stage 5Stage 5 RecoveryRecovery

- Restore body condition- Restore body condition

•- New oocyte development- New oocyte development

Stages of ReproductionStages of Reproduction

• Stage 1Stage 1 Oocyte developmentOocyte development

• Stage 2Stage 2 VitellogenesisVitellogenesis

• Stage 3Stage 3 Oocyte maturationOocyte maturation

• Stage 4Stage 4 SpawningSpawning

• Stage 5Stage 5 RecoveryRecovery

SpawningSpawning

• Release of eggs and miltRelease of eggs and milt- Fertilization- Fertilization

• Simulate natural environmentSimulate natural environment

• Dry strippingDry stripping

• Hormone inductionHormone induction

SpawningSpawning

• Simulate natural environmentSimulate natural environment

- Milk cans- Milk cans

•- Ammo boxes- Ammo boxes

•- Floating nests- Floating nests

•- Fiber mats- Fiber mats

SpawningSpawning

• Dry StrippingDry Stripping

- Express eggs and milt- Express eggs and milt- Mix together- Mix together- Add water - Add water

activate eggs and miltactivate eggs and miltclosure of micropyleclosure of micropyle

- Silting- Silting

• MS222 is toxic to eggs and milt!MS222 is toxic to eggs and milt!

Induced Spawning?Induced Spawning?• Produce hybrids that are different from the parent species;Produce hybrids that are different from the parent species;

• Produce sterile polyploid fish(for example, sterile triploid Produce sterile polyploid fish(for example, sterile triploid grass carp for aquatic weed control);grass carp for aquatic weed control);

• Synchronize reproduction of large numbers of fish for Synchronize reproduction of large numbers of fish for simultaneous spawningsimultaneous spawning

• Produce fry outside the normal spawning seasonProduce fry outside the normal spawning season

SpawningSpawning

• Induced SpawningInduced Spawning

- Stage 3 Oocyte maturation- Stage 3 Oocyte maturation

- Egg Sampling- Egg SamplingEgg sizeEgg sizeYolk clarityYolk clarityOil globulesOil globules

SpawningSpawning

• Hormone InjectionHormone Injection

- Carp Pituitary Extract- Carp Pituitary Extract- Human Chorionic Gonadotropin- Human Chorionic Gonadotropin

• Single or multiple injectionSingle or multiple injection

- Stage 3 complete in 12 - 48 h- Stage 3 complete in 12 - 48 h

• Natural Environment or Dry StrippingNatural Environment or Dry Stripping

ConclusionsConclusions

• Reproductive strategies are variableReproductive strategies are variable

• Aquaculturist provides proximate and Aquaculturist provides proximate and ultimate factorsultimate factors

• Early stages critical for egg viabilityEarly stages critical for egg viability

• Hormone treatments induce egg maturationHormone treatments induce egg maturation