ROLE OF ENVIRONMENT ON FISH REPRODUCTION

PRESENTTED TO:

TINCY VARGHESESCIENTISTS FNBP DIVISIONICAR-CIFE,MUMBAI PRESENTTED BY:

DIGANTA CHETIA

FPBMA6-06

A PRESENTATION ON

Introduction Environmental factors Photoperiod Temperature Rainfall The polyhouse techniques Conclusion.

OUT LINES

The environment is the surrounding or conditions in which a parson, animal or a plant lives or operate.

INTRODUCTION

The environmental factor or ecological factor

or eco-factor is any factor that influences living organisms.

Divided into 2 parts:Abiotic factor: temperature,

photoperiod, pH, rainfall, salinity etc.

Biotic factor: predator, parasitism etc.

ENVIRONMENTAL FACTOR

Photoperiod

Pineal organ in melatonin rhythm

Photoperiodic signals transduces by melatonin

Hypothalamic (preoptic anterior) pituitary gonadal axis

Control reproductive timing by neuroendocrine signals

PHOTOPERIOD

Regulate the production of sexual steroid and growth factor in the gonad

In spring and early summer spawners the gonadal recrudescence is often stimulated by long photoperiod with warm water temperature (Htun-Hun 1977).

Increasing photoperiod leads fast gonadal development.

Greater stimulation of vitellogenesis increased with photoperiod (Scott 1979).

Maximum response in terms of percentage of fish attaining sexual maturity occurred when there are 14 to 16 hours of light cycle.

Increasing day length/photoperiod may be the

most important cue for triggering the start of yolk production and incorporation into the developing gonad.

Water temperature is probably the major

environmental cue for the bath initiation and termination of the spawning season.

Control the melatonin production. Melatonin is the first signal of fish

reproduction.

TEMPERATURE

Temperature have direct action

on

Gametogenesis (Lofts et. al., 1968) Pituitary gonadotropin secretion

(Brelon and Billard 1977) Metabolic clearance of hormone

(Peter 1981) Responsiveness of liver to estrogen

in the production of vitellogenesis (Yaron et. al., 1980)

Responsiveness of gonad to hormonal stimulation (Jalabert et. al., 1977)

In O. latipes long photoperiod fail to stimulate

gonadal recrudescence at temperature below 10 degree C. (Yoshioka 1970).

Low temperature favor the formation of primary spermatocytes (meiotic phase), but higher temperature promote spermatogonial proliferation and spermiation (Ahson 1960).

In case of marsh killifish (Fundulus confluentus) low temperature promote the early phase of oocyte growth ( Harrington 1959).

In rainbow trout low temperature important to ovulation, otherwise the ova survive only a short time ( Billard and Breton 1977).

In gulf croaker (B. icistia) ovulation and oocyte

hydration is influenced by water temperature above 17 degree C.

Rise in temperature is also implicated in the spawning.

Stimulate the species for spawning by

Developing petrichor (dilution of electrolytes like chloride)

Lowering the temperature Increasing oxygen content Changes in pH

RAINFALL

Species that has been reported to spawn in

relation to rainfall or flood is

C. garipinus (Bruton 1979) H. fossilis ( Sundararaj and Vasal 1976) IMC (Sinha et. al., 1974) Puntius spp. (Lake 1967) Tor unicolor (Beumen 1979)

The polyhouse techniques

First established in FRC, AAU Jorhat by Dr. Bibha Chetia

Made up of UV stabilized LDPE film.

If specific environmental requirement are not met than the fish will not spawn and the gonadel component become atresic degenerates and be reabsorbed.

CONCLUSION

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