Environments Manipulationon Spawning Process

Sapto AndriyonoDepartemen Kelautan, FPK

Universitas Airlangga2013

Out Line

• Suhu (Thermal)

• Stimulasi Cahaya (Light Stimulation)

• Bahan Kimia (Chemical)

Spawning?

• Spawning refers to the release of unfertilized planktonic eggs by female fish, which is the reproductive pattern for most marine fishes.

• The eggs are fertilized shortly after release by males. Some fishes also deposit unfertilized eggs in nests where they are fertilized and develop.

There are three primary factors that influence the events leading up to spawning:

• nutritional state of the female,

• physiological factors (hormones), and

• ecological factors.

important to spawning are:

• temperature,

• photoperiod,

• tides,

• latitude,

• water depth,

• substrate type,

• salinity, and

• exposure.

Findings of several studies have demonstrated that

• variety of environmental factors such as photoperiod, temperature, rainfall, salinity;

• Biological parameters such as nutritional status and size of fish species; and

• Farm management techniques such as feeding rate and stocking density are significant in the timing of reproductive activities of some seasonal fish

Thermal

• Mempengaruhi faktor lingkungan lainnya

• Metabolisme tubuh

• Pada suhu 24oC - 6 kali lebih tinggidibanding 5oC

• Pada suhu optimum: pengambilan makanan, laju pertumbuhan, dan laju metabolisme

Thermal Reproduksi

• Perkembangan gonad suhu, makanan, cahaya dan musim

• Kematangan gonad suhu, makanan, hormonal

Peran suhu

• Laju pengeluaran GtH

• Respon pituitari pada GnRH

• Gonad Binding GtH

• Sintesis dan katabolisme steroid

• Merangsang GtH dalam proses pemecahanfolikel

• Goldfish pada suhu 20oC - GtH meningkatdalam darah

• Pada suhu <20oC ovari berkembang tetapitdk ovulasi

• Pada suhu >20oC merangsang ovulasi

Tipe ikan melahirkan

• Waktu melahirkan semakin singkat

• Pada suhu 18oC 18-22 hari

• Suhu 20oC 4-12 hari

• Hal ini dikarenakan memacu kerja enzimechorionasemelunakkan

photoperiod and periodicity

• The daylength (photoperiod), in some cases at least, is thought to influence the thyroid gland and through this the fishes’ migratory activity, which is related to gondal development (maturation).

• In high latitudes, spawning is usually associated with a definite photoperiod (and temperature), which dictates seasonal pulses of primary production in temperate regions to assure survival of larvae.

• In low latitudes, where there is little variation in daylength, temperature, and food production, other factors may be important such as timing with the monsoons, competition for spawning sites, living space, or food selection.

• Reproductive periodicity among fishes varies from having a short annual reproductive period to being almost continuous.

• Thus tropical fishes spawn nearly continuously, whereas subarctic fishes spawn predictably during the same few weeks each year.

• Generally, in species that spawn as daylengthincreases, spawning occurs earlier in the year in lower latitudes than at higher latitudes.

• In species that spawn as daylength decreases, spawning takes place earlier in the year at higher latitudes than at lower latitudes.

Photo (Cahaya)

• In the tilapia species, Ridha et al. (1998) found a positive effect of photoperiod manipulation on seed production in Oreochromis spilurus.

• Results of Biswas et al. (2005) suggested that photoperiod manipulation can be used to arrest the spawning problems in Nile tilapia (Oreochromis niloticus).

• Puckhaber (1992) worked on the Lake Manzalapopulation and applied a 6L:18D photoperiod manipulation for 28 days.

• the present study demonstrated that the timing of spawning activity in Nile tilapia can be modified by a combination of stocking density and photoperiod manipulation.

• Tropical tilapia are territorial species, exhibit a strong social hierarchy and need daily light cycle and space for their reproductive activities.

• Transferring the fish into the single compartments with enough holding space and ambient photoperiod might have broken up the social hierarchies to induce the large number of spawns in the experimental group.

• Stocking density and photoperiod technique as an effective tool in controlling spawning of farmed stocks of Nile tilapia

• Ridha and Cruz (2000) reported poorer quality of eggs (yolk sac and swim-up fry) from groups treated with combination of light intensity and photoperiod of 500 lux/18 h, 500 lux/15 h and 500 lux/12 h.

• A reduced seed kg/female/day was observed by Ridha et al. (1998) in the 29°C/13 h temperature / light duration treatment compared to the ambient condition.

• Biswas et al. (2005) obtained poorer egg quality and low fecundity in fish exposed to the 6L:6D photoperiod manipulation.

• However, no loss in egg quality such as survival of eggs and fry was experienced with the stocking density and photoperiod manipulation in the present work.

• Further investigation in this study demonstrated that plasma estradiol-17β (E2) concentration may have played an important role in relation to the effect of stocking density and photoperiod treatments on the spawning activity of female Nile tilapia.

• Consistent with Biswas (2005), this present study found that plasma estradiol-17β levels in the experimental group were low immediately after the first spawning.

• The low levels in turn may have retarded the ovarian growth due to reduced vitellogenesis(Foo and Lam, 1993).

Pheromones

• Bombykol, a fatty acid derivative that is the sex pheromone of the silkworm

• Bombykol, a 16 carbon alkohol with two sites of unsaturation, possesses a highly distinctive structure which should contribute considerably to the specificity of the signal

• Vertebrates secrete sex pheromones from gladsdistributed throughout the body, the location of which appear to be somethimes correlated with the mating behaviours of the pheromone producers.

• Male sea lampreys (Petromyzon marinus) discharge sex pheromones as urinary products that elicit a strong response in spawning-run females

• Female goldfish secrete steroidal sex hormones of presumed ovarian origin

• Many fish species spawn during the rainy season in nature. By simulating the rainy season in aquaria, difficult-to-spawn species can be induced to spawn. Rains affect the water chemistry, the water height, and the water temperature.

• In order to simulate rainy conditions, the tank level should be reduced to half its normal height. Each day add 5% of the tank volume. The water added should be very soft and slightly cooler than the tank temperature.

• To simulate the rain, use a drip system or spray bar for several hours a day and simulate storms by flashing light in a dark room. Thunder can be created by playing a recording of a storm, a recording of music with bass.

• This process will stimulate some hard-to-spawn species, but not all.

• Many species will respond to just one altered water condition, such as a series of water changes with soft water replacement, or a decrease in the water temperature.

Vocabulary

Mating Gestation

Spawning Hatching

Fertilization Breed

Incubation time Brood

Review

Source

• http://repository.seafdec.org.ph/bitstream/handle/10862/564/bspcfp_p001-053.pdf

• Hand writing.

• submit on 16 March 2015

• Explained the Fig 1, Fig 2, Fig 3, Fig 4

• One person only explaining one Figure

TERIMA KASIH