by
Herminio R. Rabanal
Private Consultant (Aquaculture)
and
V. Soesanto
Chief Technical Adviser
ASEAN/UNDP/FAO Regional Small-Scale Coastal
Fisheries Development Project
The freshwater macrouran species are usually referred to as “prawns” as distinguished from “shrimps”, the term used for the salt water forms. Most of these prawns are caridean crustaceans belonging to the family Palaemonidae. The now famous giant freshwater prawn, Macrobrachium rosenbergii, is a good example of this group. It composes an important fishery in many natural freshwater bodies in several tropical and sub-tropical countries all over the world. Within recent years controlled hatching and grow out culture of marketable forms of this species have rapidly expanded in many countries and is still growing. This species has a fine delicate flavor and commands good market price in local markets as well as in foreign trade in both developing as well as in developed countries of the world.
The status of the fishery and culture of various Macrobrachium species are summarized in Table 1. The table shows the status of the natural fishery and culture of different prawn species in different countries in the world as well as the specific bodies of waters where they occur and whenever possible data on production from natural areas. In the case of their culture, the type of culture system as well as the production if known are also summarized.
There are certain species that are of relatively higher economic importance because they grow to bigger sizes (length of 20 to 30 cm and weight of 200 to 300 grams). These are specially true, to those species that are hardy and adaptable to culture with their flesh having a delicate flavor. In Asia and the Pacific the Macrobrachium rosenbergii better known as the giant Malaysian prawn is the major species. Because artificial hatching of this species has been achieved, it has been also introduced in many countries as an object of culture operations. Another species, M. malcolmsonii, is also big species that is common in South Asia in India, Bangladesh and adjacent countries. In Australia M. australianse is the common species but M. rosenbergii has been introduced because of its larger size and superior qualities. Macrobrachium acanthurus and M. carcinus are common in the West Indies and some Latin American and North American countries. Other important species in the American continent include M. americanum, M. brasiliense, M. tenellum and M. surinamicum. In Chile another prawn species belonging to a related genus Cryphiops caementarius has a natural fishery and is also used for culture.
In countries where economic prawn species exist a fishery for those species usually occur in the major rivers of these countries. Because of the habit of many prawn species of migrating into brackish waters for spawning, such rivers connected with the sea compose favourable habitats of these prawn species. For example prawn fishery of major importance exist in the Mekong River System within Kampuchea and Viet Nam; Irrawaddy River System in Burma; the Musi River System in Sumatra and in the big rivers of the Kalimantan Provinces of Indonesia; and the rivers of Thailand flowing into the Gulf of Thailand. In Thailand also the Songkhla Lake-outlet river-complex has a consequential Macrobrachium fishery.
The development of the technique to hatch Macrobrachium rosenbergii under controlled conditions as well as the nursery rearing of the larvae and post-larval stages of this species has greatly stimulated the expansion of the culture of this species of prawns. The summary of the status of the fishery and culture of Palaemonidae species are summarized in Table 1. The situation in the Americas are summarized in Table 2. It should be noted that except for Cryphiops caementarius which is used in fresh and brackish water culture in Chile and Peru the attempts on the culture of other species in the Americas are merely laboratory and experimental cultures. However, recent introduction of Macrobrachium rosenbergii in Hawaii, California, Florida, Texas, South Carolina and Georgia has lead to the development of giant prawn culture of commercial scale specially in Hawaii and Florida. Culture in commercial scale is also practiced in Thailand, Malaysia, Indonesia and Taiwan in China.
For purposes of this discussion, the major areas of production in the different region of the world are divided into: (1) Asia and the Pacific, (2) North and Latin America, and (3) Europe and Africa, It appears from data available that Asia and the Pacific is the center of production of prawns, the Americas follow and little is actually known of the European and African situation.
Burma is a well known producer of wild stock of several species of freshwater prawn mainly the giant prawn, M. rosenbergii. It is estimated that the country produces 2 000 mt from its big river systems specially in the Irrawaddy River. Most of this is exported to nearby Thailand where it is consumed locally or re-exported to other countries. Tests on hatchery operations have been successful in the country but due to the presence of wild stocks there is no urgency for culture at present.
Thailand leads in the culture and wild stock production of the giant prawn. Even during the 70's some 2 000 to 6 000 mt of prawns were being produced annually both from natural waters and part through culture. In 1979 the prawn hatcheries in the country produced about 32 million postlarvae used for grow out rearing. In 1983 the production of freshwater prawns was 5 900 mt of which about 50 percent consists of the giant prawn. This production was valued at 421 million Baht ($19 million). For aquaculture about 18.5 million prawn juveniles were produced from hatcheries for cultures. It is estimated that about 250 mt of the above production is through culture from over 200 prawn farms in the country.
The giant prawn was introduced in Taiwan in 1971 and the technique for hatching and grow out culture were quickly adopted into the country with great success. Close to 20 million juveniles are being produced from hatcheries yearly and production of marketable sizes increased from 2 mt in 1976 to 65 mt in 1979 from 30 farms totalling 165 ha. Presently there is adequate stock from hatcheries and the production from grow out farms continue to increase as market is available.
There are a number of species of freshwater prawns in India of which four are of commercial importance (M. rosenbergii, M. malcolmsonii, M. villosimanus and M. mirabile), The first two are larger in size and are more desired. In 1979 the annual production amounted to about 350 mt for M. rosenbergii, 4 mt for M. malcolmsonii, 20 mt for M. villosimanus; and 125 mt for M. mirabile. Although hatcheries and grow out culture are on trial, there is no information on production from this source.
In Bangladesh the big rivers in that country has a natural fishery for prawn which is being exploited. It is observed however that the building of the Dakatia Dam in the upper stretches of the Ganges in India has resulted in some adverse effects in the natural stock of prawns within Bangladesh. Culture operations have been started but production is still small.
This country has large natural resource for the giant prawn and other prawn species in most of its major rivers. This is true for the rivers in Sumatra, Kalimantan, Sulawesi and Java. The production of prawn from natural waters have been fluctuating from 5 000 to 7 000 mt per year of which 60–70 percent consist of the giant prawn. Culture has been started with the construction of government hatcheries and the demonstration of grow out methods. In 1983 the prawn production was valued at Rupiah 7 400 million (= US$8 million). The increase of production through culture is expanding.
The fishery of prawns in Kampuchea and Viet Nam is based on the Mekong River System which is a natural habitat for many prawn species especially the giant prawn. In Kampuchea some 100 to 200 mt of prawn is produced yearly while 1 000 to 2 000 mt is produced in Viet Nam. There is potential for culture in both countries and there is growing interest in this work but development on this is proceeding very slowly.
The technique of controlled hatching of the giant prawn was first developed in Malaysia. Since then this procedure has been widely dispersed to other countries that were interested in prawn culture. These countries established hatcheries and had successful trials in grow out culture of the species, and development is proceeding gradually. In Singapore however, the limitation of land and present government policy has slowed down development in this sector.
In Malaysian rivers production fluctuated from 25 to 200 mt per year. Two to three million juveniles are being produced in established hatcheries but in 1981 only 1.6 million was produced. These were used for pond culture, stocking natural waters and for experiments.
A fishery for the giant prawn used to occur in most of the major rivers in the country i.e. Cagayan, Agno, Pampanga, Bicol, Jalaud, Agusan and Mindanao. Fishery for this species also existed in lake/outlet river complex such that of Laguna Lake/Pasig River, Naujan Lake/Butas River, Bato Lake/Bicol River and Mainit Lake/Agusan River. Due to human population pressure, urbanization and establishment of industries the natural fishery for prawn has been declining and has now reached very low levels. There is great interest on the culture of the giant prawn but progress has been quite slow.
Production of smaller forms, namely; M. lanceifrons and M. lanchesteri is continuing in freshwater. Over 20 000 mt annual production from Laguna Lake alone for these species has been reported.
At least four commercial species inhabiting both freshwater and brackishwater have been observed to exist in Brazil. MacrObrachium acanthurus and M. carcinus are relatively large species and may be developed for culture. The other-species are M. olfersii and M. brasiliense. There is no data available on the production from natural waters. On culture there is growing interest and experimental hatching has been successful but no commercial culture has yet developed.
It has been reported that in these two countries a brackish/freshwater species, Cryphiops caementarius occur in commercial quantities in natural waters. Likewise the culture of this species has also been reported. There is no data of production tonnage or value available, however.
Commercial species occur in natural waters in this country: M. carcinus, M. olfersii and M. americanum. There is no record of production, however, on these species. Macrobrachium rosenbergii introduced for culture and commercial production by private enterprise has been reported. There is no available data on amount and value.
At least ten species of palaemonids have been observed to occur in Mexico. At least four are commercially exploited along rivers along the Pacific coast (M. americanum, M. acanthurus, M. carcinus and M. tenellum). Yearly production varied from 200 mt to 700 mt between 1970 to 1979. Hatchery for M. americanum and M. rosenbergii (introduced) has been successful and grow out complex are now in process of being set up.
Besides indigenous palaemonid species the giant prawn, M. rosenbergii has been introduced in the state of Hawaii, Florida, California, South Carolina, Texas and Georgia. Hatchery work and culture has been very successful especially in Hawaii and Florida and many establishments are now distributing juveniles worldwide from existing American hatcheries. Commercial production of grow out ponds have expanded in Hawaii and can further expand if market can be available.
Introduction and experimental hatching of the giant prawn has been successful in the United Kingdom. Due to lack of government support for this venture its culture was later abandoned.
In West Africa, in Ghana, natural fishery for M. vollenhovenii is in existence in the Volta River System. With the establishment of the Akosombo and Kpong Dams in this river, decimation of this fishery was feared. Biology of the species and plan for its culture have been studied. Small commercial catch is still in existence in the Volta Lake and in the river below the dam. There is no data on actual amount of production.
It is noted that indigenous local fishery for wild stock of palaemonids specially Macrobrachium rosenbergii has been in existence in many countries in the world. At the beginning, fishing was lucrative and there was adequate supply in the country where they exist but at present due to increased exploitation and better means of catching natural stocks are greatly reduced. This condition is aggravated by radical man-made changes in the environment such as pollution from population centers or from newly established industries. Likewise the building of multi-purpose dams in river systems have changed the ecology of those systems to the detriment of existing prawn species. Mine pollution and silting has also greatly reduced prawn populations. The trend toward rapid and gradual reduction of prawn fisheries from natural waters appear inevitable. Two solutions are presented: (1) by preserving and maintaining environmental quality and designating sanctuary areas as conservation measures for the natural prawn fishery arid (2) by promoting the programme for the culture of cultivable prawn species. While the first measure is good, there are instances when the idea has to be subordinated by other economic needs such as the discovery of oil resource in a prawn fishery area. The better recourse appears to be the promotion of a sound programme of prawn farming.
