General Concepts in Fish General Concepts in Fish ReproductionReproduction

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 produceEggs are hardest to produce

• Hormone treatmentsHormone treatments

Reproductive StrategiesReproductive Strategies

• Maximize survival of eggs and fryMaximize survival of eggs and fry– natural habitat vs. man-madenatural habitat vs. man-made

• Ultimate FactorsUltimate Factors– food supplyfood supply– absence of predatorsabsence of predators– water qualitywater quality

Reproductive StrategiesReproductive Strategies

• Ultimate FactorsUltimate Factors

• Proximate Factors Proximate Factors – environmental cuesenvironmental cues– anticipate future spawninganticipate future spawning

Day Length and Day Length and TemperatureTemperature

-5

0

5

10

15

20

25

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

(What fish have we seen that fits this?)(What fish have we seen that fits this?)

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

(Any examples?)(Any examples?)

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 developmentOocyte development– Gonadotropin independentGonadotropin independent– Body size dependentBody size dependent

Stages of ReproductionStages of Reproduction

• Stage 1Stage 1 Oocyte developmentOocyte development

• Stage 2Stage 2 VitellogenesisVitellogenesis– Egg yolk productionEgg yolk production– High nutritional demandHigh nutritional demand– Longest phaseLongest phase

Stages of ReproductionStages of Reproduction

• Stage 1Stage 1 Oocyte developmentOocyte development

• Stage 2Stage 2 VitellogenesisVitellogenesis

• Stage 3Stage 3 Oocyte maturationOocyte maturation– Germinal vesicle migrationGerminal vesicle migration– Resumption of meiosisResumption of meiosis– Water uptakeWater 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 environmentOptimum environment– Mating behaviorsMating 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 conditionRestore body condition– New oocyte developmentNew 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– FertilizationFertilization

• Simulate natural environmentSimulate natural environment

• Dry strippingDry stripping

• Hormone inductionHormone induction

SpawningSpawning

• Simulate natural environmentSimulate natural environment– Milk cansMilk cans– Ammo boxesAmmo boxes– Floating nestsFloating nests– Fiber matsFiber mats

SpawningSpawning

• Dry StrippingDry Stripping– Express eggs and miltExpress eggs and milt– Mix togetherMix together– Add waterAdd water

• Activate eggs and miltActivate eggs and milt closure of micropyleclosure of micropyle

– SiltingSilting

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

SpawningSpawning

• Induced SpawningInduced Spawning– Stage 3 Oocyte maturationStage 3 Oocyte maturation– Egg SamplingEgg Sampling

• Egg sizeEgg size• Yolk clarityYolk clarity• Oil globulesOil globules

SpawningSpawning

• Hormone InjectionHormone Injection– Carp Pituitary ExtractCarp Pituitary Extract– Human Chorionic GonadotropinHuman Chorionic Gonadotropin

• Single or multiple injectionSingle or multiple injection– Stage 3 complete in 12 - 48 hStage 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 Hormone treatments induce egg maturationmaturation