Origins of modern freshwater prawn culture

Freshwater prawns have been reared in captivity, either through introducing wild-caught juveniles or by trapping them, along with other crustaceans (e.g. Penaeus spp. and Metapenaeus spp.) and fish, in tidal ponds and paddy fields, for example in the Indian sub-continent and Malaysia (Wickins 1976), from time immemorial. However, modern aquaculture of this species has its origins in the early 1960s. Ling & Costello (1979) and Ling (1977) recalled that experiments on the rearing of prawn larvae had been conducted by fisheries biologists all over the world but had been unsuccessful before then. In 1961 the first major milestone was achieved at the Marine Fisheries Research Institute in Penang, Malaysia, when the Food and Agriculture Organization (FAO) expert Shao-Wen Ling (Fig. 1.1) discovered that freshwater prawn (M. rosenbergii) larvae required brackish conditions for survival.

Dr Ling's poignant description of his first experiments (Ling 1977), which included his observations that successful mating (rather than the previously observed cannibalism) occurred when the females underwent a pre-mating moult, is part of the folk-lore of aquaculture. This pioneer then discovered, through trial and error, that the addition of salt or soy sauce proved a key to larval survival: freshwater prawn larvae need brackishwater to survive beyond 5 days.

This had not been realised before because the mature adult prawns had been collected in totally freshwater, sometimes up to 100 miles (160 km) distant from the sea. This observation quickly led to the rearing of larvae through all their developmental stages in 1962, as first described by Ling & Merican (1961), and the production of sufficient juvenile prawns to initiate grow-out experiments in ponds in 1963 (Ling & Costello 1979). News of this success spread rapidly and generated worldwide interest in freshwater prawn culture. Within 10 years, research and development projects had commenced in most Asian countries, as well as in Europe, the Americas and Africa.

While Ling's discoveries were fundamental, it was the work of another pioneer, Takuji Fujimura (Fig. 1.2) that made the commercial development of freshwater prawn culture possible. This was the second major milestone in the history of freshwater prawn farming. Fujimura's research in Hawaii commenced in 1965, with the introduction ofbroodstock of M. rosenbergii from Malaysia (Ling & Costello 1979). Lee (1979) provided a detailed account of the early days of prawn farming in Hawaii. Within 3 years, the activities of Fujimura and his team in the Anuenue Fisheries Research Center in Honolulu resulted in the development of mass-rearing techniques for commercial-scale hatchery production ofprawn postlarvae (PL) (Fujimura & Okamoto 1972). Following the ready availability of PL for stocking, grow-out experiments spawned commercial farms in Hawaii and elsewhere throughout the 1970s. In Asia, both Thailand and Taiwan (Chen 1976) were initiating what has since become a significant industry in both countries.

Further details about the life of Shao-Wen Ling (Chew 1990) and Takuji Fujimura (Wong & Brock 1991), who both died in 1990, were given in tributes published by the World Aquaculture Society (WAS). The WAS had granted honorary life membership of the Society to these two 'fathers' of freshwater prawn farming, in 1974 to Shao-Wen Ling and in 1979 to Takuji Fujimura.

Fig. 1.1 Shao-Wen Ling, who first completed the life cycle of Macrobrachium rosenbergil. (Reproduced from Chew 1990; copyright 1990 with permission of the World Aquaculture Society)

Based on the success of the Hawaiian hatchery and grow-out research and commercial experiences, broodstock were introduced, both from Southeast Asia and from Hawaii, into many countries where M. rosenbergii was not indigenous. Introductions occurred notably in North, Central and South America, but also in Africa, and even (for experimental environmentally controlled culture in temperate regions) in Europe. For example, in Florida around 1970, Paul Mulvihill and his son Michael became the first to raise freshwater prawns commercially in continental USA (Rosenberry 2007). Takuji Fujimura himself played a key role in many of these international developments, not only in arranging the supply of broodstock but also, more significantly still, by providing training in the technology his team had developed. This essential education was provided both in Hawaii and through the consultancy work conducted by Fujimura around the globe during the 1970s and 1980s.

Some examples of initial introductions of M. rosenbergii are provided in Table 1.1. Though multiple introductions have occurred in some countries, usually from farm pond or research sources, much ofthe prawn culture in countries where M. rosenbergii is not indigenous was originally based on a very small initial broodstock. This made the industry in those countries vulnerable to genetic degradation, a phenomenon which has been observed in several countries (Chapter 17). The huge industry in China has recognised this danger and regularly introduces new broodstock from abroad. Genetic degradation has also been observed in countries where this species is indigenous but brood-

Fig. 1.2 Takuji Fujimura (second from the left), who pioneered the large-scale hatchery production of Macrobrachium rosenbergil. (Reproduced from Wong & Brock, 1991; copyright 1991 with permission of the World Aquaculture Society.)

stock are obtained only from grow-out ponds, rather than the capture fisheries.

The third important milestone in the history offreshwa-ter prawn farming occurred when the United Nations Development Programme (UNDP) decided to fund an FAO-executed project, named 'Expansion of Freshwater Prawn Farming', in Thailand. This project built on the existing work of the Thai Department of Fisheries, led by Som-sak Singholka and his team at the Chacheongsao Fisheries Station in Bangpakong, Chonburi. The work of the project was initiated by Somsak Singholka, with the help of Takuji Fujimura (Fujimura 1978), and a visiting FAO project manager, Herminio Rabanal, in 1978. Following

Table 1.1 Examples of introductions of giant river prawns (M. rosenbergii) for farming purposes.

Country where introduced

Date

Source

Reference

Argentina

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