FISH FARMING (SHRIMP AND CATLA)

Fish farming or pisciculture involves raising fish commercially in tanks or enclosures such as fish ponds, usually for food. It is the principal form of aquaculture, while other methods may fall under mariculture. A facility that releases juvenile fish into the wild for recreational fishing or to supplement a species’ natural numbers is generally referred to as a fish hatchery. Worldwide, the most important fish species produced in fish farming are carp, tilapia, salmon, and catfish.

Demand is increasing for fish and fish protein, which has resulted in widespread overfishing in wild fisheries. China provides 62% of the world’s farmed fish. As of 2016, more than 50% of seafood was produced by aquaculture.

Farming carnivorous fish, such as salmon, does not always reduce pressure on wild fisheries. Carnivorous farmed fish are usually fed fishmeal and fish oil extracted from wild forage fish. The 2008 global returns for fish farming recorded by the FAO totaled 33.8 million tonnes worth about $US 60 billion.

SHRIMPS:-

Arthropoda, class Crustacea, subclass Malacostraca, order Decapods, suborder Macrura)

A considerable part of the fisheries in India is constituted by the crustaceans, such as shrimps, shrimps and lobsters. shrimps and shrimps, which belong to the group Natantia, are similar in appearance; shrimps, however, are smaller in size. Lobsters are robust, heavily aromoured creatures; they are exclusively marine and are included under the group Reptantia. All the three decapods have elongated bodies divisible into two easily recognizable parts, viz. The cephalothorax and the abdomen. The cephalothorax is formed by the fusion of the head and thorax, and is made up of not less than thirteen segments, five in the head and eight in the thorax. The abdomen is composed of six distinct segments with a tail piece or telson behind the last segment. Each of these segments generaally carries a single pair of appendages, which are useful in the normal functioning of the body. Head appendages are two parirs of antennae, sensory in function, and a pair of mandibles and two pairs of maxillae, used in capturing and masticating food. Thorax possesses three pairs of maxillipedes, probably used for holding the prey, and five pairs of walking legs for crawling. Abdominal appendages are adapted for swimming. Sexes are separate and the reproductive organs are mainly situated in the cephalothorax.

Penaeus Fabr:- The rostrum is serrated on both the edges; a gill is attached to the body wall on the last thoracic somite; exopodites are present on all or all but the last pair of thoracic legs. Larges shrimps caught from the Indian seas belong to this genus.

P. indicus

BENG.:- Chapda chingri;

MAL.- Vella-chemmeen naran- chemmeen.

The body is somewhate laterally compressed an when alive the shrimp is rather white and translucer with a large number of brown, grey of green dot over the carapace and abdomen. The antennae an tips of the appendages are pink. It is fairly large in size, growing to about 20 cm. in length, and occur commonly along the entire coast-line of the country in coastal waters, estuaries, coastal lakes and back waters.

M. affinis

MAL. Kazhadnthan-chemmeen.

The rostrum is curved in this species, and the last pair of thoracic legs in both sexes, when stretched forwards, project beyond the tips of the antennal scale. In respect of size and a few other characters it resembles M. monoceros (Fabr.), described below. It occurs along both the coasts, but is not very common in the backwates and estuaries.

M. brevicornis

BENG. Dhanbone Chingri.

The rostrum in this species is shot, rarely reaching to the middle of the second joint of the antennular peduncle. Fully grown forms rarely exceed 13 cm. in length. It is the commonest penaeid species of West Bengal, found in vast numbers in the inundated paddy dield during the rainy season. It is foud, though in smaller numbers, on the Bombay coast also.

P.Stylifera

MAL. – Karikkadi-chemmeen.

It is characteristically reddish brown in colour. The presence of a number of small spines on either side of the pointed extremity of the telson further distinguishes this species from others. Adult shrimps reach a length of about 13 cm. Its distribution is mainly on the west coast, and it is caught in large numbers along the Kerala coast during December-May. A variety of this species, viz. coromandelica Alcock, with two spines on each side of the telson, has also been recorded from various places along the east coast.

P.styliferus

BENG. – Ghora chingri.

This species inhabits both marine and brackish waters and contributes substantially to the shrimp fishery of the Gangetic delta and the Bombay coast. It seldom exceeds 5 cm. in length.

P.tenuipes (Henderson)

This species is easily recognizable by the long and slender fourth and fifth pairs of walking legs. Its habitat is similar to that of P. styliferus and it is caught in large numbers off the Bombay coast.

M.malcolmsonii is very common in the Chilka lake in Orissa, Hooghly estuary, Godavari, and Ganga towards the close of the monsoon and is mainly a freshwater species tolerating brackish water. During this period, mostly the gravid female shrimps are caught. They do not exceed 23 cm. in length.