Transcript General Concepts in Fish Reproduction General Considerations • • • • • Natural habitat of species Body size and first parity Annual vs.

General Concepts in Fish
Reproduction
General Considerations
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Natural habitat of species
Body size and first parity
Annual vs. multiple spawning
Eggs are hardest to produce
Hormone treatments
Reproductive Strategies
• Maximize survival of eggs and fry
– natural habitat vs. man-made
• Ultimate Factors
– food supply
– absence of predators
– water quality
Reproductive Strategies
• Ultimate Factors
• Proximate Factors
– environmental cues
– anticipate future spawning
1M
15 ay
-M
ay
1Ju
15 n
-J
un
1Ju
15 l
-J
u
1- l
Au
15 g
-A
u
1- g
Se
15 p
-S
ep
1O
15 ct
-O
c
1- t
N
15 ov
-N
o
1- v
D
e
15 c
-D
ec
1Ja
15 n
-J
an
1Fe
15 b
-F
eb
1M
15 ar
-M
ar
1Ap
15 r
-A
pr
Day Length and
Temperature
25
20
10
Water Temperature (C)
15
Day Length (h)
5
0
-5
Reproductive Strategies
• Synchronous
– All eggs are spawned and the fish dies
(What fish have we seen that fits this?)
Reproductive Strategies
• Synchronous
– All eggs are spawned and the fish dies
• Group Synchronous
– Multiple spawning and seasonal spawners
(Any examples?)
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
Stages of Reproduction
• Stage 1 Oocyte development
– Gonadotropin independent
– Body size dependent
Stages of Reproduction
• Stage 1 Oocyte development
• Stage 2 Vitellogenesis
– Egg yolk production
– High nutritional demand
– Longest phase
Stages of Reproduction
• Stage 1 Oocyte development
• Stage 2 Vitellogenesis
• Stage 3 Oocyte maturation
– Germinal vesicle migration
– Resumption of meiosis
– Water uptake
Stages of Reproduction
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Stage 1 Oocyte development
Stage 2 Vitellogenesis
Stage 3 Oocyte maturation
Stage 4 Spawning
– Optimum environment
– Mating behaviors
Stages of Reproduction
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Stage 1 Oocyte development
Stage 2 Vitellogenesis
Stage 3 Oocyte maturation
Stage 4 Spawning
Stage 5 Recovery
– Restore body condition
– New oocyte development
Stages of Reproduction
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Stage 1 Oocyte development
Stage 2 Vitellogenesis
Stage 3 Oocyte maturation
Stage 4 Spawning
Stage 5 Recovery
Spawning
• Release of eggs and milt
– Fertilization
• Simulate natural environment
• Dry stripping
• Hormone induction
Spawning
• Simulate natural environment
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Milk cans
Ammo boxes
Floating nests
Fiber mats
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!
Spawning
• Induced Spawning
– Stage 3 Oocyte maturation
– Egg Sampling
• Egg size
• Yolk clarity
• Oil globules
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
Conclusions
• Reproductive strategies are variable
• Aquaculturist provides proximate and
ultimate factors
• Early stages critical for egg viability
• Hormone treatments induce egg
maturation