Reproduction Fisheries Continued

Question 1

Considerations when analyzing reproduction

Answer 1

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!

Question 2

Another term for sex identification

Answer 2

gross gonadal morphology

Question 3

Female sex identification organ

Answer 3

Ovaries

Question 4

Male sex identification organ

Answer 4

Testes

Question 5

Physical Characteristics of Ovaries

Answer 5

Typically yellow or orange in coloration
Granular consistency
Vascularization
Central lumen

Question 6

Physical Characteristics of Testes

Answer 6

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

Question 7

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

Answer 7

Size

Question 8

Another term for assessing maturation

Answer 8

gross gonadal condition

Question 9

What does GSI stand for?

Answer 9

Gonadosomatic Index

Question 10

What does Gonadosomatic Index equal?

Answer 10

Gonad weight/somatic weight

Question 11

Somatic Weight

Answer 11

Total body muscle - everything beyond the reproductive system.

Question 12

What are some key characteristics for assessing maturation?

Answer 12

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

Question 13

What are the variables used to assess maturity?

Answer 13

Length or age at first maturity

Question 14

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

Answer 14

Length or age at 50% maturity.

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

Question 15

What are the two stages of Ovarian Development?

Answer 15

Sexually Immature
Sexually mature

Question 16

What are the stages of a sexually mature fish species?

Answer 16

Immature oocytes
Oocyte maturation (several stages as yolk incorporated)
Vitellogenesis (yolk production)
Production in the liver
Transport to ovary
Hydration of mature oocytes
Occurs shortly before spawning
Volume considerations
Ovulation (post-ovulatory follicle)

Question 17

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

Answer 17

Primary growth
a small cell with a central nucleus;

Unyolked
all oocytes without yolk

Partially yolked
early stages of yolk deposition; some yolk granules are

Yolked
all contain many, small to large yolk globules

Hydrated
the largest oocytes

Atretic
Cell degeneration

Question 18

Male gonad phases

Answer 18

Ripe
Resting

Question 19

What are the three types of spawning strategies?

Answer 19

Synchronous spawners
Group synchronous spawners
Asynchronous spawners

Question 20

Synchronous spawners

Answer 20

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

Question 21

Group synchronous spawners

Answer 21

(e.g., monkfish, cod)
at least two populations of oocytes can be distinguished at any one time: a population of larger oocytes (the ‘batch’) and a population of smaller, more heterogeneous oocytes from which subsequent batches are recruited
indeterminant fecundity

Question 22

Asynchronous spawners

Answer 22

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

Question 23

Label the three types of spawning strategies.

Answer 23

Question 24

How can spawning strategies help us understand maturity schedules?

Answer 24

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

Question 25

How to determine the frequency of spawning?

Answer 25

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

Question 26

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

Answer 26

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

Question 27

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

Answer 27

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)

Question 28

Why does all of this matter?

Answer 28

Determines fecundity

Question 29

Fecundity

Answer 29

The number of eggs spawned in a reproductive season

Question 30

Determinate fecundity

Answer 30

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

Question 31

Indeterminate fecundity

Answer 31

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

Question 32

How to estimate the fecundity of batch spawners?

Answer 32

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

Question 33

What is important to be aware of when assessing fecundity?

Answer 33

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