Macrobrachium Rosenbergii (De Man, 1879)

Food and Agriculture Organization of the United Nations Fisheries and for a world without hunger Aquaculture Department Cultured Aquatic Species Information Programme Macrobrachium rosenbergii (De Man, 1879) I. Identity V. Status And Trends a. Biological Features VI. Main Issues b. Images Gallery a. Responsible Aquaculture Practices II. Profile VII. References a. Historical Background a. Related Links b. Main Producer Countries c. Habitat And Biology III. Production a. Production Cycle b. Production Systems c. Diseases And Control Measures IV. Statistics a. Production Statistics b. Market And Trade Identity Macrobrachium rosenbergii De Man, 1879 [Palaemonidae] FAO Names: En - Giant river prawn, Fr - Bouquet géant, Es - Langostino de río View FAO FishFinder Species fact sheet Biological features Males can reach total length of 320 mm; females 250 mm. Body usually greenish to brownish grey, sometimes more bluish, darker in larger specimens. Antennae often blue; chelipeds blue or orange. 14 somites within cephalothorax covered by large dorsal shield (carapace); carapace smooth and hard. Rostrum long, normally reaching beyond antennal scale, slender and somewhat sigmoid; distal part curved somewhat upward; 11-14 dorsal and 8-10 ventral teeth. Cephalon contains eyes, antennulae, antennae, mandibles, maxillulae, and maxillae. Eyes stalked, except in first larval stage. Thorax contains three pairs of maxillipeds, used as mouthparts, and five pairs of pereiopods (true legs). First two pairs of pereiopods chelate; each pair of chelipeds equal in size. Second chelipeds bear numerous spinules; robust; slender; may be excessively long; FAO Fisheries and Aquaculture Department chelipeds equal in size. Second chelipeds bear numerous spinules; robust; slender; may be excessively long; mobile finger covered with dense, though rather short pubescence. Abdomen has 6 somites, each with pair of ventral pleopods (swimmerets). Swimmerets of sixth abdominal somite stiff and hard and, with the median telson, serve as the tailfan. Eleven distinct larval stages. Images gallery Large male [Photo: Deborah Ismael] Large wild-caught males [Photo: Methil Narayanan Kutty] BC, OC and SM prawns [Photo: Assaf Barki] Berried females [Photo: Takuji Fujimura] Profile Historical background Although reared in captivity from time immemorial, modern farming of this species originated in the early 1960s when FAO expert Shao-Wen Ling, working in Malaysia, found that freshwater prawn (Macrobrachium rosenbergii) larvae required brackish conditions for survival. This discovery led to larval rearing on an experimental basis. By 1972 the Hawaiian team led by Takuji Fujimura had developed mass rearing techniques for commercial-scale hatchery production of prawn postlarvae (PL). This development spawned the first commercial farms in Hawaii and elsewhere. Both Thailand and Taiwan Province of China became pioneers in FAO Fisheries and Aquaculture Department modern giant river prawn culture. The introduction of broodstock, initially from Hawaii and Thailand, into non-indigenous areas around the world began in the 1970s. The first major FAO project designed to expand the culture of this species began in 1978 in Thailand. Since then, giant river prawn culture has developed in every continent, particularly in Asia and the Americas. Global production had increased to over 200 000 tonnes/yr by 2002 (including production in Viet Nam). Furthermore, there is considerable production of other freshwater prawn species, notably M. nipponense that does not appear in official statistics. Main producer countries Main producer countries of Macrobrachium rosenbergii (FAO Fishery Statistics, 2006) Note: Viet Nam is also a major producer of farmed M. rosenbergii; this is not illustrated on this map because Viet Nam includes its production within the category 'freshwater prawns, shrimps nei' (not elsewhere included) when making data returns to FAO. Habitat and biology This species lives in tropical freshwater environments influenced by adjacent brackishwater areas. It is often found in extremely turbid conditions. Gravid females migrate downstream into estuaries, where eggs hatch as free-swimming larvae in brackishwater.Before metamorphosis into postlarvae (PL), the planktonic larvae pass through several zoeal stages. After metamorphosis, PL assume a more benthic life style and begin to migrate upstream towards freshwater. Larvae swim actively tail first, ventral side uppermost. From PL onwards prawns swim forwards, dorsal side uppermost. From metamorphosis onwards prawns can also walk, not only on the sub-stratum but also over damp areas including stones by river edges, up vertical surfaces (small waterfalls, weirs, etc.) and across land. Larvae mostly consume zooplankton (mainly minute crustaceans), very small worms, and larval stages of other crustaceans. Postlarvae and adults are omnivorous, eating algae, aquatic plants, molluscs, aquatic insects, worms, and other crustaceans. Males and females have different growth rates and males exhibit heterogenous individual growth (HIG); these are vitally important factors in grow-out management. Three distinct male morphotypes (and a number of intermediary types) exist: small male (SM), orange claw males (OC), and blue claw males (BC). The normal male developmental pathway is SM → OC → BC. BC males have extremely long second pereiopods; those of OC males are golden coloured; SM have small, slim, almost translucent claws. The type and behaviour of the males affects the growth rates of other prawns. The transition from rapidly growing OC to the slowly growing BC morphotype follows a "leapfrog" growth pattern. An OC metamorphoses into a BC only after it has become larger than the largest BC in its vicinity. The presence of this new BC male then delays the transition of the next OC to the BC morphotype, causing it to attain a larger size following its metamorphosis. BC males dominate OC males, regardless of their size, and suppress the growth of SM. Production Production cycle FAO Fisheries and Aquaculture Department Production cycle Production cycle of Macrobrachium rosenbergii Production systems Seed supply When required for hatchery use, female broodstock are usually obtained from grow-out ponds but also sometimes from capture fisheries. Normally, "berried" (egg-carrying) females are only used once. Commercial farms in tropical regions do not normally maintain captive broodstock for breeding purposes but adults are over-wintered indoors in temperate regions in order to stock ponds with PL as early as possible in the short grow-out season. The typical male to female ratio in broodstock holding systems is 1-2 BC males or 2-3 OC males per 20 females, at a total stocking density of 1 prawn per 40 litres. Within a few hours of copulation, fertilization occurs externally, as the eggs are transferred to the brood chamber beneath the abdomen. The eggs remain adhered to the female during embryonic development, which lasts about 3 weeks. At hatching, free- swimming zoeae are produced. Between 5 000 and 100 000 eggs are carried, depending on the size of the berried female. Eggs are orange until 2-3 days before hatching, when they become grey-black. Some seed (PL; juveniles) is obtained from the capture fishery where M. rosenbergii is indigenous, typically in the Indian sub-continent, but most is now hatchery-reared. First stage zoeae are just under 2 mm long and grow, through 11 larval stages, to almost 8 mm at metamorphosis into PL. Individual metamorphosis can be achieved in as little as 16 days but usually takes much longer, depending on environmental conditions. In commercial hatcheries, most larvae metamorphose by day 32-35 at the optimum temperature (28-31 °C). Larval rearing typically occurs in 12‰ brackishwater, and hatcheries are either flow-through (where a proportion of the rearing water is regularly replaced) or recirculating (where a variety of systems involving physical and biological filters are used to minimise water use). Either type of hatchery may be inland or coastal. Inland hatcheries produce brackishwater by mixing freshwater with seawater transported from the coast, brine trucked from salt pans, or artificial seawater. Some flow-through hatcheries use a "greenwater" system, which involves fertilization to encourage the growth of phytoplankton (mainly Chlorella spp.), which is believed to improve FAO Fisheries and Aquaculture Department water quality and increase larval survival; others operate a "clearwater" regime. Feeding systems vary widely but typically include brine shrimp (Artemia salina) fed several times per day at first, reducing to a single daily feed by larval stage 10. Prepared feed (usually an egg custard containing mussel or fish flesh, squid, or other ingredients) is introduced at stage 3 and its feeding frequency is increased towards metamorphosis. Some hatcheries are integrated with nursery and grow-out facilities. Nursery Although some farmers stock grow-out ponds with young PL, many either purchase larger juveniles or rear PL in their own nursery ponds before transfer to grow-out ponds. In temperate areas with a limited grow-out season, environmentally controlled indoor nurseries are used to increase animal size before stocking outdoors as soon as temperatures become high enough. Indoor nurseries are stocked at 1 000-2 000 PL/m³, depending on whether substrates are used or not. Outdoor nurseries may be stocked with newly metamorphosed PL or with juveniles from an indoor nursery. Typically, stocking rates are 1 000/m²

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