Last Pack

Question 1

What treatment would you use for hormonal sex reversal? What are the problems with this method?

Answer 1

Methyl Testosterone - only in food

• poor market acceptance
• must treat all production fish
• obtain fry less than 10 days from hatch

Question 2

what are the four ways of controlling reproduction?

Answer 2

• monosex culture
• early cropping of single year class
• predator stocking
• cage culture

Question 3

What are the 6 methods of creating a monosex culture?

what is the desired result?

Answer 3

-manual sexing
-hybrids
-hormonal sex reversal
-GMT tilapia
-triploids
-high temperature incubation
» all boys no girls «

Question 4

5 ways to sex an oreochromis

Answer 4

• males longer pointed dorsal and anal fins
• more developed jaws in males
• color at breeding
• males larger
• location of urogenital openings

Question 5

what are the 3 advantages of hybrids?

Answer 5

• do not treat all production fish
• less expensive (labor, material)
• better market

Question 6

problems for triploiding tilapia

Answer 6

• females still in stock - slow growers
• must shock minutes post fertilization
• hand stripping
• apply heat shock from 27* to 42*C post fertilization for 3 minutes
• causes high mortalities

Question 7

what is the trade name of YY supermales?

Answer 7

GMT -
genetically male tilapia
guarunteed male tilapia

Question 8

2 methods of creating GMT. what percentage of monomales do you wind up with?

Answer 8

i) androgenesis: 1/2 yy 1/2 xx

ii) hormonal monosexing: 1/4xx 1/2 xy 1/4yy

Question 9

list one observation which could be made microscopically that would indicate a newly developing oocyte has entered prophase 1 of meiosis

Answer 9

presence of lipid droplets

Question 10

Name 2 chromosome manipulation techniques which require application o pressure or temperature shock to suppress the first cleavage division of embryonic development

Answer 10

gynogenesis
androgenesis
tetraploids

Question 11

twice during oogenesis, meiosis stops while other developments occur. what two events trigger the resumption of meiosis after these arrests?

Answer 11

vitelogenesis finished, fertilization

Question 12

what is the main reason for producing tetraploid fish?

Answer 12

to create triploid in the future

Question 13

what two fish organs are responsible for synthesis of the phospholipoprotein referred to as vitellogenesis?

Answer 13

liver, gonads

Question 14

at any temperature, why does oogenesis take longer in large fish eggs compared to small eggs?

Answer 14

larger eggs = more time of deposition of the yolk in eggs

Question 15

what would you observe in the ovary of a fish that displays asynchronous oogenesis?

Answer 15

eggs at all different stages of development

Question 16

what hormone serves fish as the gonadotropic hormone releasing hormone inhibitory factor?

Answer 16

dopamine

Question 17

what chemical can be used to competitively bind to estrogen receptors, to eliminate estrogen’s negative feedback on recrudescence, when inducing spawning in fish?

Answer 17

tomoxfine

Question 18

what is the main environmental cue that triggers recrudescence in temperate zone fish?

Answer 18

photoperiod

Question 19

what organ secretes melatonin?

Answer 19

pineal gland

Question 20

name two compounds which can be combined with reproductive hormones to produce a slow release, injectable pellet for induction of recrudescence in fish?

Answer 20

cellulose, coconut oil, polymers, cholesterol

Question 21

when during oogenesis are circulating gonadotropin concentrations higher in fish?

Answer 21

just before ovulation

Question 22

pelagophiles scatter non-adhesive eggs in open water. what characteristic of the egg controls their density and determines their depth of incubation?

Answer 22

oil content

Question 23

give an example of an auxilary respiratory structure that might be found on a larval fish from a low oxygen environment?

Answer 23

external gills, fin folds

Question 24

what environmental incubation problem is overcome by the many species of fish which build bubble nests?

Answer 24

low O2

Question 25

what cichlid subfamily do the genera oreochromis and sartherodon belong to?

Answer 25

pseudocrenilabinae

Question 26

what sex ratio should be sued in a tilapia spawning tank for intensive recirculation culture?

Answer 26

1:1

Question 27

list 2 methods by which aquaculturists in countries with limited technology are able to control unwanted reproduction in tilapia ponds

Answer 27

predator stocking
cage culture
hand sexing

Question 28

list 3 disadvantages of hormonal sex reversal in the culture of tilapia

Answer 28

a) illegal
b) must treat all fish
c) expensive
d) timing is critical
e) expensive

Question 29

What would be an acceptable range of protein concentration in a pelleted tilapia brood food?

Answer 29

25-35% higher protein = less fry

Question 30

at which stage of meiosis are fish eggs normally fertilized?

Answer 30

metaphase 2

Question 31

if homozygous female tetraploid fish (i.e.: XXXX) are bred with hormonally masculinized homozygous male fish (ie XX) what is the sex and sex chromosome compliment of the fry?

Answer 31

sex: female

sex chrmosome: 3x

Question 32

what purpose might an upwardly curved tail on a fish larvae serve?

Answer 32

to help the larvae to stay in the water column ‘near surface’.

Question 33

which two genera of the cichlid tribe tilapiini feed largely on phytoplankton?

Answer 33

oreochromis

sartherodon

Question 34

what two morphological characteristics of the digestive system would identify as largely vegetarian evolved to eat frequent meals?

Answer 34

small stomach

long intestine

Question 35

what are the results of high temperature incubation? at what temp and for how long?

Answer 35

many perish, but it increases the proportion of males by a lot.
bring fish up to 36* over 2 hours. maintain 36* for 10 days. decrease to 28* over 2 days

Question 36

what is a subsistence method of monosex culture?

Answer 36

early cropping of single year class;

high density stocking of heavily fertilized water

Question 37

what are the stocking ratios from tilapia:predators?

Answer 37

10:1 - 250:1

Question 38

hapa

Answer 38

asian cage name

Question 39

what subfamily is tilapia in? what tribe?

Answer 39

Pseudocrenilabrinae

tilapiini