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AqTech > Topic 4F > Flashcards

Topic 4F Flashcards

1
Q

Define fecundity

A

The no. of eggs ripened by aquatic species during a spawning season/event
- Fecundity inversely proportional to amount of parental care

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2
Q

Define gametogenesis

A

Production of gametes or creation of haploid sex cells via meiosis

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3
Q

Oogenesis

A

Egg production in females

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4
Q

Spermatogenesis

A

Sperm production in males; sperm + semen = milt

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5
Q

Steps of oogenesis

A
  1. Follicle development
  2. Yolk vesicle formation
  3. Vitellogenesis (true yolk formation)
  4. Envelope formation
  5. Maturation
  6. Ovulation
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6
Q

Steps of spermatogenesis

A
  1. Mitosis proliferation
  2. Meiosis
  3. Spermiogenesis
  4. Spermiation
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7
Q

When identifying fish reproductive biology, have to determine:

A
  1. Proportion of stock that is reproductively mature
  2. Size/age at first maturity
  3. Current reproductive status
  4. Nature of reproductive cycle for particular population/species
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8
Q

List the methods of determining reproductive bio/sexual maturity

A
  1. Gross anatomical criteria (visually examine gonads)

2. Gonadal somatic index (compare gonad size to fish size)

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9
Q

List the type of reproduction with relation to fecundity

A

Oviparous (least fecund)
Ovoviviparous
Viviparous (most fecund)

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10
Q

Gonadal somatic index (GSI)

A

[Gonad mass/body mass (including gonad)] x 100

- NO UNIT

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11
Q

What affects fecundity (besides reproduction type)

A
  • size of fish

- nutritional status of female

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12
Q

List the types of fecundity

A
  1. Absolute fecundity
  2. Relative fecundity
  3. Population fecundity
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13
Q

Absolute fecundity

A

No. of ripe eggs in one spawning season/year

- Varies due to age, length, weight, species

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14
Q

Relative fecundity

A

No. of eggs produced in a season per somatic weight of fish (eggs/gram)

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15
Q

Population fecundity

A

No. of eggs pawned by population in one season

  • Sum of fecundities of all females
  • (Expected fecundity of an average female} x (no. of breeding females in the pop.)
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16
Q

Size of eggs

A
  • Negative correlation b/w egg size & env. conditions

- Low fecundity = larger eggs (larger yolks)

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17
Q

State the factors that affect reproduction (broad)

A
  1. Endogenous hormone signals –> physiological factor, hormone signals
  2. Exogenous factors –> ecological factor
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18
Q

List the exogenous factors affecting reproduction

A
  1. Temperature
  2. Photoperiod
  3. Tides
  4. Water depth
  5. Substrate type
  6. Salinity
19
Q

Temperature (exogenous factor)

A
  • Most crucial
  • Controls maturation & spawning
  • Within narrow temperature range
  • Limiting factor during some gametogenesis stages
  • Determines sex of fish
20
Q

Photoperiod (exogenous factor)

A
  • Influences thyroid gland, migratory activity & gonadal development
  • Highly associated with endogenous rhythm
21
Q

Water depth (exogenous factor)

A
  • Spawn at one depth, live in diff depths during other times
22
Q

Substrate type (exogenous factor)

A

Related to type of breeding strategies (spawning on diff substrates)

23
Q

Salinity (exogenous factor)

A

Various degrees of mixing, precipitation, freshwater runoff may alter spawning habits, change spawning sites due to salinity change

24
Q

Tides (exogenous factor)

A
  • May spawn on daily/monthly tidal cycle or on a diel cycle

- usually after spring tides

25
Q

Endogenous factors

A
  • endogenous rhythm controls activities of reproduction –> migration + timing of repro, morpholigcal changes, start courtship behaviour
  • via hormones & nerves (aka neuroendocrine factor)
  • Influenced by ecological factors –> e.g. photoperiod, temp, salinity (e.g. ↓ duration of photoperiod = ↑ melatonin = ↓ gonadotropin prod. = ↓ gonadal activity
26
Q

Hormone/enzyme produced by pituitary gland + function (fish reproduction)

A
  1. Gonadotropins –> e.g. FSH, LH, Gonadotropin release hormones + Gonadotropin release inhibiting factor
    - Controls gametogenesis
    - Production of sperm/eggs
  2. Steroids –> e.g. 11α-ketotestosterone
    - controls vitellogenesis (yolk formation) & spawning
27
Q

Hormone/enzyme produced by liver + function (fish reproduction)

A

Insulin-like growth factors (e.g. Igf1)

  • Regulates growth
  • Gonad development
28
Q

Hormone/enzyme produced by pineal gland + function (fish reproduction)

A

Melatonin

  • Regulates gonadotropins
  • Mediates photoperiodic effect sin the pituitary
29
Q

Hormone/enzyme produced by bones + function (fish reproduction)

A

Arginine-vasotocine

- Influence LH release & interfere with production of gonadotropin release hormones

30
Q

Hormones/enzymes produced by optic gland + function (crustacean reproduction)

A
  1. Gonadotropins
    - Stimulate gonad development
  2. Gonad-inhibiting hormone
    - Inhibits vitellogenesis
  3. Moult-inhibiting hormone (MIH)
    - Inhibits MIH
31
Q

Hormone/enzyme produced by cerebral ganglia + function (mollusc reproduction)

A

Caudodorsal cell hormone (CDCH)

  • Induce ovulation
  • Stimulate egg formation
  • Induce egg-laying behaviour
32
Q

List the organ/gland that produces hormones/enzymes that affects reproduction (fish, crustacean, mollusc)

A

Fish

  1. Pituitary gland
  2. Liver
  3. Pineal gland
  4. Bones

Crustacean
1. Optic gland

Mollusc
1. Cerebral ganglia

33
Q

Artificial reproduction

A
  • Process to fertilise eggs with sperm out of natural reproduction timing
  • Done by manipulating environmental conditions (exo factors) or injection of hormones (endo factors)
34
Q

Benefits/function of artificial production

A
  1. ↑ frequency of production
  2. ↑ survival rate of embryos
  3. Control batch production
35
Q

Before conducting artificial reproduction:

A
  1. Ensure broodstock is well fed & recovered after last spawning
  2. Ensure optimal water quality parameters 3. separation of males/females whenever possible (diet different)
  3. Ensure broodstock ready –> gonads mature
  4. Ensure optimal water quality parameters
36
Q

During female finfish reproductive cycle

A
  • Presence of bloated belly
  • ↑ed aggression
  • Livebearers (e.g. guppy) have obvious gravid spot
37
Q

Once reached maturity (male finfish)

A
  • Stores sperm
38
Q

Artificial reproduction in fish

A
  • Do not reproduce as well in captive breeding –> stress-induced environment –> ↓es reproductive behaviour & oogenesis
  • Stimulation of env. conditions required –> enhancement of diet + control water quality
  • Hormonal injection/physical handling at later stage –> stimulate spawning
  • Physical handling: stripping (female) & milting (male)
  • Eggs & sperm mixed gently in container
39
Q

Artificial reproduction in molluscs

A
  • Sacrifice indiv. to observe maturity of gonads –> extraction of gametes to view under microscope
  • Mainly influenced by temp
  • -> ↑er temp = ↑ somatic & gametogenic growth; drop in temp = encourage spawning
40
Q

Artificial spawning methods (mollusc)

A
  1. Temperature exposure
  2. Aerial exposure
    (1. + 2. = stimulate intertidal conditions)
  3. Chemical treatment
41
Q

Ablation (artificial reproduction in crustaceans)

A
  • Removal of one eyestalk, synchronise with lunar cycle
  • X Organ Sinus Gland (XOSG) –> found in eyestalk; contains moult inhibiting hormone (MIH) and gonad inhibiting hormone (GIH)
  • Remove XOSG (in eyestalk) releases gonadotropins –> initiate reproduction + exhibit spawning behaviour
42
Q

Artificial insemination (Crustaceans)

A
  • Mainly shrimps
  • Removal of spermatophore from male shrimps
  • Insert into female via open thelycum
43
Q

Climate change & aquaculture

A
  • Climate change = affect salinity & temp
  • ↑/↓ in temp influence general metabolism, production; seasonality relative fecundity, no. of spawning
  • Fish observed to spawn earlier/later
  • Change in reproduction timing = affect overall ecology
  • Mismatch b/w seasonality of larvae & zooplankton (food availability)
  • High temp amplify impact of hormone-disrupting chemicals (from pollution) –> e.g. long term effects of clotrimazol (chemical), believed to disrupt hormones & interfere w sex ratio = ↓ mate search success & ↑ inbreeding potential

AqTech (11 decks)

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