A Blue Revolution manifesting Ultra-Sonography in Pisciculture

Techniques of Induced Breeding –

1. Removal of Glands: are removed either by, foramen magnum (removing vertebral parts adhering to skull), and dissecting head (used in exceptional cases);

• Preservation of Glands: it can be preserved in 100% Ethyl Alcohol; Acetone for Temperate Countries; Glycerin is also a preservative agent;

• Preparation of Gland Extract: volume of gland should commensurate with the total quantity of fish to be breed. The Gland is dried in air by using blotting paper, followed by the Gland is taken in tissue homogeniser with little amount of distilled water. It is of utmost importance that the correct dilution rate is 0.2 ml / kg of body weight of the fish. Finally, the pituitary extract is then centrifuged and only the supernatant solution is used for injection;

• Selection of Brooders: The brooders must be healthy enough and ripe within 02 – 04 years of age, and preferably 01 – 05 kg’s of body weight;

• Injecting the Brooders: Determination of the correct dosage of pituitary extract to the breeders is very important and depends upon the size and state of maturity of the recipient (breeders) as well as upon the state of maturity of the donor for the glands. It is mention-worthy that males are not administered the preliminary dose. The female is given a preliminary dose of 02 – 03 mg / kg of body weight. The second dose is administered on the female after a gap of 06 hours to the proportion of 05 – 08 mg / kg of body weight. The male is then given the first dose of injection with female @ 2-3mg / kg of body weight.

The pituitary extract is administered into the body of breeders by means of hypodermic syringe either intra muscular or intra peritoneal.  The dose may be depending upon the maturity of fish, age, sex and also the environmental conditions. For intra muscular injection the fish is laid on its side while held in hand net and the needle is inserted either in the caudal peduncle or in the shoulder. For intra peritoneal the injections are given in the bases of paired pectoral fins.

• Spawning: takes place within 03 – 06 hours following the second dose. The factors conducive for a successful spawning are:

• Climate – 24°C to 31°C with cloudy days and rainy periods. Light drizzling following heavy rains is ideal. In absence of rain artificial showers are used.  
• Water – Flowing water is preferred.  
• Turbidity – 100 ppm to 1000 ppm.
• Light – It is known to bring that light may help in early maturation and spawning of fish.

A successful induced breeding results in the spawn of fertilised eggs. The fertilised eggs are like pearls, transparent, whereas the unfertilised eggs are opaque or whitish.

Why is Hilsa Fish conserved and propagated through circular cage culture in the Ganges:

While conducting a research study, it became evitable that there was no significant difference between upstream and downstream of the Farakka Barrage, while assessing the seasonal water quality parameters.  However, “Tenualosa ilisha” were recorded only in downstream of the barrage showing physical hindrance posed by the Farakka barrage on their migration. “Tenualosa ilisha” population showed a steep decline in stretches above the Farakka Barrage. To increase the fish population, 27173 Hilsa brood fish were ranched in upstream of Farakka Barrage.

With the objective of developing captive breeding and rearing protocols of Hilsa, a pond rearing facility had been developed with the primary objective of stocking fingerlings with an average size of 22.84 ±1.56 gram. In this endeavour, breeding on boat was performed, together with ICAR-CIFA, Rahara, at Godakhali utilising wild Hilsa brood fishes. This yielded a huge number of spawns which are being reared in grow-out pond of ICAR-CIFA facility at Rahara.

To set up a greater number of experimental ponds for rearing, Hilsa pond rearing facility (0.4 hectare) has been established at Kolaghat, West Bengal. The pond has been stocked with fingerlings of the size 22.84 ± 1.56 grams collected from river Roopnarayan and also local ponds. Fishes are regularly fed with Hilsa Plus twice a day. Mass culture facilities for Chlorella and mixed zooplankton (small aquatic invertebrates less than 2 mm long, including copepods, cladocerans, and rotifers, living in the water columns of lakes or slow-moving streams) have been developed at pond site and are supplemented in the pond on weekly basis.

When the quality of the plankton in the water deteriorates, a mixture of Mustard Cake (Sorshe Khol), Almond Peel Crush Powder (Badam Khol), and other minerals is used to improvise the water quality. It is of omnipotent importance that Mustard Cake hinder the growth of Virus, Nematodes as well as various other microorganisms, while Almond Peel Crush Powder or Badam Khol is Vitamin E enriched, a good source of antioxidant, anti-microbial, anti-viral, photoprotective and prebiotic activities of plants.

Two separate experiments have been conducted with Chlorella vulgaris to standardise its optimum growth conditions. The water quality parameters of Hilsa pond are monitored at regular intervals to maintain a uniform environmental condition for the stocked Hilsa.

The most astonishing characteristic of this project is somewhat unbelievable to many Hilsa Lovers. Till now we knew that a Hilsa Fish succumbs immediately to its catchment; but the scientific team of ICAR-CIFRI has made ‘an impossible’ happen ‘Possible’. To ascertain the maturity of the Hilsa Fish, it is first made UNCONSCIOUS, followed by an ULTRA SONOGRAPHY determining the maturity, and then the Hilsa Fish is turned CONSCIOUS before letting it go to the water. It is considered to be a miniature adoption of the century old Coronary Angiography Bypass Surgery.

During recent monitoring, a fish of 689 g (43.6 cm) was recorded at Kolaghat, which is gained during rearing of 3 years. This attainment of size is the highest reported from any such attempt in India. The growth of pond-reared Hilsa is better than that of open water revealing that there is a possibility of aquaculture of Hilsa. Water quality is almost freshwater with salinity of about 0.4 – 0.5 ppt and conductivity of about 800 – 1000 µS/cm. Water is alkaline (pH 7.4-7.5) with sufficient dissolved oxygen (7.4-7.5 mg/l).

As per the scientific team of ICAR-CIFRI, it is not too far that the prospects of a successful captive Hilsa culture would enable humanity to feed on the Hilsa, as and when we want.

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