In this article we will discuss about the meaning and important species of prawns.
Meaning of Prawns:
The terms “shrimps” and “prawns” have been used interchangeably and the terminology varies from nation to nation. However, they are closely related belonging to crustaceans of the families Penaeidae and Palaemonidae. The standardisation of the terms was one of the agenda at the “Prawn Symposium” of the Indo-Pacific Fisheries Council held at Tokyo in 1955.
The decision arrived at was that; ‘prawn’ should be applied to the Penaeids, Pandalids and Palemonids and the word ‘shrimp’ to the smaller varieties belonging to other families. However, in aquaculture literature (T.V.R. Pillay, 2005) prawns are referred to as freshwater forms of Palaemonids and shrimps for the rest, particularly for marine forms.
Prawns are the larger variety and are freshwater and brackish water inhabitants. Shrimps are smaller marine forms. Prawn and shrimps are tasty and highly nutritive, containing vitamins A and D. They are palatable due to the presence of glycogen and free amino acids, with low fat content in their muscles.
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Culture of these crustaceans has been an age old practice in ponds and paddy-fields in the form of extensive culture. Intensive and semi-intensive culture of these forms has been a recent technological advancement of aquaculture.
This sort of culture was triggered by increased market demand in recent years coupled with inadequacy of the capture fishery landings to meet the demand. In fact, shrimps and prawns have become high-value commodities, mainly because of their export market. Due to the prospects associated with exports, private sectors with support of the government have resorted to such culture practices.
Important Species of Prawns:
There are about 150 species of freshwater prawns all over the world, of which only 40 species are found distributed in the rivers, reservoirs and estuaries of India. Some important species are Macrobrachium rosenbergii, M. malcolmsonii, M. idae, M. mirabile, M. rude, M. lamarrei, M. scabriculum, M. villosimanum and M. birmanicum choprai.
Among these, M. rosenbergii, the giant freshwater prawn, has been found to be most suitable for culture, owing to its faster growth rate, higher tolerance to wider range of salinity and temperature, and less cannibalistic tendency.
Among the Penaeus species, the important ones cultured in Asia are tiger shrimp Penaeus monodon, the Indian or white shrimp Penaeus indicus [Fig. 8.3(a)], the banana shrimp Penaeus merguiensis [Fig. 8.3(b)], the green tiger or bear shrimp Penaeus semisulcatus [Fig.8.3(c)], the oriental shrimp Penaeus orientalis and the Kuruma shrimp Penaeus japonicus [Fig.8.3(d)].
The species cultured in Taiwan is the red tailed shrimp Penaeus penicillatus. Among the Metapenaeus shrimp species cultured in several Asian countries are M. monoceros, M. dob- soni, M. affinis, M. brevicornis and M. ensis.
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Some important shrimp species of economic value, also cultured outside Asia, are the Kuruma shrimp Penaeus japonicus [Fig. 8.3(d)], the white leg shrimp Penaeus vannamei [Fig. 8.3(e)], the blue shrimp Penaeus stylirostris, the Mediterranean shrimp (triple-grooved shrimp) Penaeus kerathurus, Penaeus notialis, the brown shrimp Penaeus aztecus, pink shrimp Penaeus duorarum, etc.
Prawn and Shrimp, due to their high growth rate (marketable size can be attained by 3 to 6 months), are most suitable for culture. They also have high tolerance to operational stress, omnivorous feeding habit and are of high economic value.
The only pitfall in their culture is collection of seed and this hindrance has been removed by the introduction of induced breeding technique and hatchery operations. In India, M. rosenbergii and P. mondon, due to their large size are most suitable for culture in freshwater and brackish water, respectively. The Indian white shrimp P. indicus is the next preferred species for culture.