Introduction

THE WORDS ‘PRAWN’ AND ‘SHRIMP’ are often used synonymously. Actual use is geographically dependent. For example, animals of the genus Macrobrachium are referred to as freshwater prawns in Australia and freshwater shrimp in the United States of America (USA). In its statistical data, FAO refers to the genus Macrobrachium as freshwater prawns but also uses the word prawn for many species of marine shrimp, including the banana prawn (Fenneropenaeus merguiensis), the giant tiger prawn (Penaeus monodon) and the kuruma prawn (Marsupenaeus japonicus) (FAO 2001).

This manual is intended to be a practical guide to the farming of freshwater prawns and is meant primarily for extension, rather than research workers. Its contents are a synthesis of practical experience and published information. The manual also has some relevance for the enhancement of freshwater prawn fisheries, since this requires the provision of hatchery-reared animals for stocking purposes. The introduction of M. rosenbergii and related species into reservoirs and the enhancement of existing capture fisheries has had some current success, notably in Brazil, India and Thailand. Further developments will require hatchery-reared postlarvae (PL) and juveniles for stocking purposes. Although the new manual is primarily concerned with aquaculture, parts of it (particularly the sections on broodstock, hatchery management and marketing) are also relevant to the enhancement of freshwater prawn fisheries. Further reading on the topic of capture fisheries and enhancement is available in New, Singholka and Kutty (2000). Those interested in the science that supports freshwater prawn farming can find a comprehensive review in New and Valenti (2000).

Although several species of freshwater prawns are currently being cultured, this manual deals exclusively with the farming of the major commercial species (Macrobrachium rosenbergii), which is indigenous to South and Southeast Asia, parts of Oceania and some Pacific islands. M. rosenbergii has been imported into many other tropical and subtropical areas of the world and is the species most favoured for farming purposes.
The use of the words ‘freshwater prawns’ and ‘prawns’ in this manual, except where otherwise specifically qualified, refers to M. rosenbergii. This species remains by far the major subject of cultivation because a global market for it evolved during the 1990s and is currently being further developed. Other species of Macrobrachium are now also being farmed, mainly for domestic consumption, and modifications of the techniques described in this manual can be derived to support this development. Such modifications need to take account of the different environmental requirements of the other species, especially in the larval stages. Reference to the culture of other Macrobrachium spp. is contained in Kutty, Herman and Le Menn (2000).
In the previous FAO manual on this topic, the hatchery and pond-rearing techniques described were generally based on those applied in freshwater prawn culture in Thailand in the early 1980s. Only one system of culture, namely the operation of flow-through hatcheries followed by monoculture in ponds, was fully described. This manual broadens the scope by drawing on experience in recirculation hatcheries and monoculture from other countries, notably Brazil and the USA, and by stressing the opportunities for alternative systems of grow-out, including polyculture and integrated culture After a brief section on the biology of M. rosenbergii, the manual deals with the selection of sites for hatchery and grow-out facilities. It then covers the maintenance of broodstock and the management of the hatchery, nursery and grow-out phases. Following a section on harvesting and the post-harvest handling of market-sized prawns, the manual includes a section on marketing, an important topic that was not covered in the previous document. The text of the manual concludes with some references to financial matters and a short bibliography for further reading. Several other important topics, such as the preparation of feed for freshwater prawn larvae, and a glossary, are provided in the annexes.
General background information, which should be useful for extension workers and students is provided in the introduction and in Chapter 1. Chapters 2-8 (especially sections 3-6) and the annexes contain the main technical content of the manual, which is of direct relevance for farmers as well as students and extension workers. The different audiences addressed by various parts of the manual are reflected by the writing style chosen for each section. As far as possible, the technical sections that are specific to the hatchery and growout management of freshwater prawns (especially the material presented in text ‘Boxes’ are written in ‘cookbook’ English, whereas more ‘scientific’ language is used in Chapter 1 and some of the annexes, for example.
The author and the FAO Fisheries Department hope that you will find the manual useful and stimulating, and would welcome constructive criticism, so that the manual may be improved in future editions.