Reproduction Fisheries Flashcards

1
Q

Considerations when analyzing reproduction

A

Lifespan

Onset of maturity
Early
Late

Interplay = spawning opportunities

Number and size of eggs

Number of batches/season

Relationship with size/age

Not all eggs are the same!

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2
Q

Another term for sex identification

A

gross gonadal morphology

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3
Q

Female sex identification organ

A

Ovaries

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4
Q

Male sex identification organ

A

Testes

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5
Q

Physical Characteristics of Ovaries

A

Typically yellow or orange in coloration
Granular consistency
Vascularization
Central lumen

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6
Q

Physical Characteristics of Testes

A

Typically white or off-white in coloration
Smooth consistency
No central lumen

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7
Q

How can gonads help with understanding productive cycles and/or timing?

A

Size

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8
Q

Another term for assessing maturation

A

gross gonadal condition

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9
Q

What does GSI stand for?

A

Gonadosomatic Index

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10
Q

What does Gonadosomatic Index equal?

A

Gonad weight/somatic weight

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11
Q

Somatic Weight

A

Total body muscle - everything beyond the reproductive system.

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12
Q

What are some key characteristics for assessing maturation?

A

Gonads increase in size prior to spawning season
Remain large through spawning season
Become smaller in “resting phase”

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13
Q

What are the variables used to assess maturity?

A

Length or age at first maturity

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14
Q

What percentage is a standard often used to assess a population’s maturity?

A

Length or age at 50% maturity.

Example: 50% of the population is mature at a certain length or certain age.

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15
Q

What are the two stages of Ovarian Development?

A

Sexually Immature
Sexually mature

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16
Q

What are the stages of a sexually mature fish species?

A

Immature oocytes
Oocyte maturation
Yolk production
Hydration of mature oocytes
Ovulation

17
Q

What are the stages of Oocyte Development based on American shad?

A

Primary growth

Unyolked

Partially yolked

Yolked

Hydrated

Atretic

18
Q

Male gonad phases

A

Ripe
Resting

19
Q

What are the three types of spawning strategies?

A

Synchronous spawners
Group synchronous spawners
Asynchronous spawners

20
Q

Synchronous spawners

A

(e.g., Pacific salmonids, eels)
all mature oocytes, once formed, grow and ovulate in unison
determinant fecundity

21
Q

Group synchronous spawners

A

(e.g., monkfish, cod)

at least two populations of oocytes can be distinguished at any one time

indeterminant fecundity

22
Q

Asynchronous spawners

A

(e.g., anchovies, hake)
Multiple and daily spawning
oocytes of all stages are always present without dominant populations
indeterminant fecundity

23
Q

Label the three types of spawning strategies.

A
24
Q

How can spawning strategies help us understand maturity schedules?

A

The spawning frequency could impact when 50% of the population is considered mature.

25
Q

How to determine the frequency of spawning?

A

originally modal analysis of oocyte sizes (three size classes of oocytes = three spawnings per season)

26
Q

What is the issue with oocyte size to determine the frequency of spawning?

A

Post-ovulatory follicles (POFs) remain in the ovary for a period after ovulation and can be staged by histological examination

27
Q

What was the Hunter & Goldberg analysis on the histological examination?

A

Conditioned northern anchovy to spawn

Used histological analysis to follow the fate of POFs

Could reliably stage POFs as 0 – 24 hr old, 24 – 48 hr old (evaluated with “blind” readers)

28
Q

Why does all of this matter?

A

Determines fecundity

29
Q

Fecundity

A

The number of eggs spawned in a reproductive season

30
Q

Determinate fecundity

A

The standing stock of advanced oocytes is proportional to annual fecundity (synchronous spawners)

31
Q

Indeterminate fecundity

A

The standing stock of advanced oocytes does not indicate annual fecundity (group-synchronous and asynchronous spawners)

32
Q

How to estimate the fecundity of batch spawners?

A

Fecundity = (batch size) (spawning frequency) (spawning duration)

33
Q

What is important to be aware of when assessing fecundity?

A

Not all developed eggs are necessarily spawned (atresia, resorption)