Fish Reproduction

are female ovaries paired?

Yes

Description of female ovaries

Large, yellowish in color, granular in texture

how much weight are fish ovaries during reproductive periods ?

30-70% body weight

what is sexual dimorphism

changes in size or shape between males and females in a species.

what is dichromatism

changes in color between males and females in a species

do all fish have sexual dimorphism and dichromatism ?

No, many lack sexual dimorphism and dichromatism

are male testes smooth or rough?

Smooth

are testes a white or dark structure

white structure

How much body weight are testes during the reproductive periods?

12% of body weight

Where does sperm (milt) in fish like salmon exit through?

the abdominal pore

where do chondrichthyes store sperm?

sperm stored in seminal vesicle

Do teleosts have a sperm duct?

Yes

how many tubercles do male creek chubsuckers have on both sides of their head?

three

when are tubercles present on males?

during the breeding season

do females have tubercles?

No, females do not have tubercles.

What are tubercles made of?

Keratin

what are tubercles used for?

species recognition, fighting, and defense of nests

what are the 4 stages of the development of fish embryos called?

1. cleavage

2. blastula

3. epiboly

4. gastrula

what is cleavage? (referring to the development of fish embryos)

Early cell division that occurs in a fertilized egg

what is blastula? (referring to the development of fish embryos)

Early stage of development in embryo that forms a hollow ball of cells.

what is epiboly? (referring to the development of fish embryos)

spreading and thinning of ectoderm and movement of the mesoderm and endoderm layers to the inside. Begins after the blastula stage is complete

what is Gastrula? (referring to the development of fish embryos)

refers to the formation of the gut

R-seleion is a selective strategy that farvors:___,___,___

1. The production of large numbers of offspring with low survival rates

2. Short-life span which means smaller organism

3. little care for offspring once egg is fertilized

Example of an R-selection fish

Danios. They are egg scatterers that provide no parental care and produce many eggs

K-selection is a selective strategy that favors:___,___,___

1. The production of few offspring with high survival rates

2. longer life spend which means bigger organisms

3. long term parental care for offspring or born at a larger size

Example of K-selection fish?

Bonnethead sharks.

what are the 5 major stages of development for Fry?

1. Embryonic

2. larval

3. juveniles

4. adult

5. senescent

what is the saltasional theory?

when development proceeds gradually until an abrupt change in behavior occurs once the threshold is reached .

What is the alternative theory?

entire process is gradual and stages are arbitrary

what is the embryonic period?

when the developing individual is entirely dependent on nutrition provided by the mother. yolk sac or placenta-like connection in viviparous fish.

Embryonic period into three pieces: _____

1. cleavage egg

2. embryo

3. free embryo

what is the free embryo stage?

embry no longer curled, more fish like, but still reliant on yolk sac or mother for nutrition

when does the larval period begin?

when the fish is able to catch food

when does the larval period end ?

when the axial skeleton forms

how long can the larval period last in marine fish?

two weeks - months

In marine pelagic larvae: mortality is ______(high or low). Also, its a time of ______

High; larval dispersal

in fry, are juveniles organs fully formed and have mature ganoids??

yes, organs are fully formed; no, ganoids are not mature yet

Where do sturgeons hatch?

In freshwater rivers

When do sturgeons head to sea?

head to sea as sub-adults

why do sturgeon return to frshwater?

To spawn and reproduce

how long can sturgeons live for?

can live up to 60 years

are sturgeon K-selection or R-selection?

K-selection

where do catadromous spend most of their life?

in freshwater

why do catadromous migrate to salt water?

to spawn and reproduce.

What is the best known examples of a catadromous fish?

eels

Do catadromous fish eat while in saltwater?

normally, no they do not

Are all eels catadromous?

No, some eels from the pacific or atlantic ocean never enter freshwater

saltwater reared = high or low levels of strontium?

high levels of strontium

freshwater reared = high or low levels of strontium?

low levels of strontium

where do european flounders usually travel in to?

estuaries and river

Where are juvenile european flounders common?

estuaries or rivers (low salinity)

why do adult european flounders leave freshwater in the fall?

To spawn in saltwater.

are european flounders nektonic or planktonic?

planktonic (drifts around freely, in this case, towards the shore)

Where do thin lipped grey mullets migrate to feed?

freshwater habitats

when do thin lipped grey mullets spawn?

they spawn in large groups during the summer and early fall

Where do thin lipped grey mullets spawn?

saltwater and further offshore

are thin lipped grey mullets K-selection or R-selection

K-selection

Where do adult thin lipped grey mullets thrive?

in low salinity water

what are non-gaurders

fish that do not protect their eggs and young after spawning

what are the 2 categories of non-gaurders

1. scatter eggs unhidden (open substrate spawners)

2. Behaviorally hide eggs (brood spawners)

in what position do non-gaurders typically breed?

in large groups with no structure

What are Gaurders

they guard embryo until it hatches and sometimes care for larval stages

do guarders lack structure?

No, gaurders have courtship and territorial behavior

example of a gaurder fish

freshwater angelfish will pair off, defend egg site, and attack intruders

except among cichlids, who are embryos gaurded by? (Male or female)

Usually Male

what do bearers do?

fish bearers carry their embryos and sometimes their young around with them

What is an adaptation that external bearers have?

Short-term attachment of embryos to the adult mouth brooders

Examples of external bearers

sea catfish, cichlids, pipefish, and seahorses.

what are internal bearers ?

females carry embryo and/or young internally. they produce a small amount of active offspring.

examples of internal bearers

guppies and sharks

in aquaculture, what happens after eggs are produce at one facility?

the eggs then get shipped to another for hatching and grow-out.

how are eggs shipped?

on ice in shipping boxes and gradually brought up to room temperature

what is hatching dependent on for rainbow trout?

temperature

attributes of hatching rainbow trout in 55F :

hatching 3 weeks post fertilization or 4-7 days of being received as eyed eggs

attributes of hatching rainbow trout in 45F:

hatching 7 weeks of post fertilization

what do suppliers and hatcheries use to disinfect eggs

iodine

methods that eggs could be counted in

1. Von Bayer Method V-trough

2. Electronic egg encounter

3. displacement method

what are trays used for in aqualture/ hatcheries?

used to house a large amount of eggs. they are transferred before hatching.

can upwelling incubators be used for eggs?

yes

how much are trout fed per day for the first 2-3 weeks?

10% of their body weight

how often are trout fed ?

every 15 minutes is ideal

what is the recommended stocking density for shipping?

1 pound of fish per cubic foot

can fish be vaccinated?

depending on the species