3. History of introductions of Penaeid shrimp

The use of alien^[11] animal species to increase food production and income has a long history and has been an established practice since the middle of the 19th century. Controversy over the use of alien species arises from the many highly publicized and spectacular successes and failures. The FAO database of introduced aquatic species^[12] (DIAS) reports that aquaculture development has been the primary reason cited for most introductions, accounting for 40 percent of all cases. It also indicates that the number of introductions (65 percent being intentional) has increased exponentially since 1940. Most of these introductions are of fish, with only 6 percent or 191 records being of crustaceans. Such movements have been facilitated by recent advances in transport, which have made large-scale movements of many species increasingly easy. They are also directly related to the rapid global development of aquaculture and the demand for new species to culture (DIAS; Fegan et al., 2001).

3.1 Natural range of Penaeus vannamei and Penaeus stylirostris

Penaeus vannamei is native to the Pacific coast of Mexico and Central and South America as far south as Peru, in areas where water temperatures are normally over 20ºC throughout the year (Wyban and Sweeny, 1991; Rosenberry, 2002). It is not currently known whether there is one population or if isolated populations exist, although there appear to be differences between stocks from various areas under culture conditions.

Penaeus stylirostris is native to the Pacific coast of Central and South America from Mexico to Peru, occupying the same range as P. vannamei, but with higher abundance, except in Nicaragua at the peak of the range of P. vannamei (Rosenberry, 2002). It has recently been demonstrated that there are at least six morphologically and genetically distinct populations of P. stylirostris in the Gulf of California, Mexico alone (Lightner et al., 2002), raising the probability that there will be variations in their suitability for aquaculture.

3.2 Early movements for experimental culture

The first experimental movements of Penaeid shrimp began in the early 1970s when French researchers in Tahiti developed techniques for intensive breeding and rearing of various alien Penaeid species including P. japonicus, P. monodon and later P. vannamei and P. stylirostris.

In the late 1970s and 1980s, P. vannamei and P. stylirostris were transferred from their natural range on the Pacific coast of Latin America from Mexico to Peru. From here, they were introduced to the North-western Pacific coast of the Americas in the USA and Hawaii, and to the Eastern Atlantic coast from Carolina and Texas in the north through Mexico, Belize, Nicaragua, Colombia, Venezuela and on to Brazil in the south. Most of these countries now have established aquaculture of these species. Penaeus monodon and P. japonicus were also introduced in the 1980s and 1990s from Asia to various Latin American countries and the USA, including Hawaii, (where SPF populations have been established), and Ecuador and Brazil, where introductions were not successful.

Introductions of P. vannamei to Asia began in 1978/79, when it was introduced to the Philippines (FAO correspondent), and in 1988 to Mainland China (FAO correspondent). Of these first trials, only Mainland China maintained production and started an industry. In 1988, a batch of P. vannamei PL were introduced into Mainland China from the Marine Science Institute of Texas University. By 1994, the Chinese aquaculturists were producing their own PL, and commercial shrimp culture began in the late 1990s. A similar early introduction of less than 100 000 PL P. vannamei into the Philippines in 1987 from "Agromarina" in Panama was not successful (Fred Yap, per. com.) and culture of this species was suspended for another ten years (Table 2).

SPF P. stylirostris have also been experimentally introduced to many Asian countries (including Brunei, Taiwan Province of China, Myanmar, Indonesia and Singapore) from secure breeding facilities in Mexico and the USA. These introductions began in 2000, but have yet to make a major impact on the culture industries in those countries (with the exception of a small industry in Brunei), but without notable problems so far. Penaeus stylirostris was also introduced into Thailand and Mainland China in 2000, but has yet to make much impact in these countries.

3.3 Movement for commercial production

The introductions of P. vannamei to non-native areas of the Americas, the Pacific and lately to Asia, have had a significant positive effect on the production capacities of the countries involved. This is probably the first time that this has ever been recorded with cultured shrimp. However, potential negative impacts are already being reported and will be discussed further in this report.

Brazil

Due largely to an inability to breed and rear local shrimp species intensively (especially under high temperatures and low dissolved oxygen conditions), Brazil first imported P. japonicus in 1980, P. monodon in 1981 and P. vannamei and P. stylirostris in 1983, followed by P. penicillatus in 1994 (Roberto Andreatta et al., 2002; de Barros Guerrelhas, 2003). Commercial production of P. vannamei began in 1983, but it was not until 1995 that this species became predominant. This was due largely to the importation of highly productive Panamanian stocks (in 1991), the mastering of its captive maturation, fast growth, efficient food conversion and high survival rates obtainable in ponds and its good market potential in Europe and the USA.

USA

Penaeus vannamei was first imported to the USA as postlarvae from Panama in 1985 into South Carolina, USA. It has steadily risen in popularity to become the main species of shrimp farmed in North America (Sandifer et al., 1988). Penaeus monodon were also imported into South Carolina from Hawaii in 1988 and subsequently escaped and have since been captured along the Eastern Atlantic coast down to Florida, although it is still not considered to be established (McCann et al., 1996).

Six species of Penaeid shrimp (P. vannamei, P. monodon, P. stylirostris, P. japonicus, P. chinensis and P. indicus) have been introduced into Hawaii for culture and research purposes. Only P. vannamei is currently under commercial pond culture, although there still remain stocks of most species (except P. indicus which failed to clear pathogen screening and was destroyed), which are used for generation of SPF and SPR stocks for sale to other countries (Wyban, per. com.; Eldridge, 1995; Hennig et al., 2003). Most of the original stocks were brought into Hawaii between 1978 and 1985, and imports have subsequently slowed due to fears over the importation of alien viruses (Eldridge, 1995). Brock (1992) provides a list of the known shrimp viruses which were already present in Hawaii in 1992. Although individuals of P. vannamei, P. monodon, P. stylirostris and P. japonicus have escaped culture, none is known to be locally established (Brock, 1992; Eldridge, 1995).

Table 2: Importation of P. vannamei and P. stylirostris in Asian countries and the Pacific

Pacific Islands

Although there are approximately 20 indigenous species of Penaeid shrimp amongst the islands of the South Pacific and Hawaii, nine alien species have been introduced, initially into Tahiti and New Caledonia, since 1972. These include P. monodon, P. merguiensis, P. stylirostris and P. vannamei (since 1972, Table 2), Metapenaeus ensis, P. aztecus, P. japonicus and P. semisulcatus (since 1973) and P. indicus (in 1981) (Eldridge, 1995). In addition, P. stylirostris were introduced into French Polynesia (from Mexico and Panama) in 1978, into Fiji (from Hawaii) in the mid-1990s and P. vannamei were introduced to Fiji (from Hawaii) in 2002 (Ben Ponia, per. com.) (Table 2).

Of all these species, only one, P. merguiensis has so far become established in Fiji. Despite release into the wild, P. japonicus has not become established (Eldridge, 1995). Despite all the research efforts stretching back over 30 years, shrimp farming is still a very small industry in the Pacific Islands, with a total production of 2 272 metric tonnes in 2002, mostly of P. stylirostris from New Caledonia (Ben Ponia, per. com.). Constraints include limited domestic markets, transportation costs and social, economic and climatic problems (Adams et al., 2001).

Asia

The first commercial shipment of SPF P. vannamei broodstock from the Americas to Asia was from Hawaii to Taiwan Province of China in 1996 (Wyban, 2002) (Table 2). Initial successes with the maturation, larval rearing and culture of this species in Taiwan Province of China led to a huge demand for broodstock and to the first introductions of wild broodstock from many sources in Latin America in 1997. Initial production of 12 metric tonnes/ha of 12-15 g shrimp in 75 days were reported (Wyban, 2002), similar to current production levels in Thailand and Indonesia.

By mid-1998, farmers in both Mainland China and Taiwan Province of China were producing their own pond-reared broodstock. In early 1999, TSV, imported with wild broodstock from Latin America, began to cause significant (80 percent in three days) mortality of juvenile shrimp in ponds in Taiwan Province of China (Tu et al., 1999; Yu and Song, 2000). In addition, WSSV was also causing mortalities, and runt deformity syndrome (RDS) and slow growth due to Infectious Hypodermal and Haematopoietic Necrosis Virus (IHHNV) was common. These disease problems led to decreased profits and the tendency to use cheaper pond-reared broodstock, without consideration of genetic makeup or biosecurity. This led to inbreeding and increased introduction of disease through hatchery produced PL. Despite these problems, the production of P. vannamei in Taiwan Province of China (7 633 metric tonnes) in 2002 was higher than that of P. monodon (1 828 metric tonnes).

After Taiwan Province of China, Mainland China began importing SPF broodstock of P. vannamei from Hawaii in 1998 (Wyban, 2002) to augment their own production of pond-reared broodstock. Similar early successes led to huge imports of broodstock, both SPF from Hawaii and non-SPF^[13] from Taiwan Province of China, throughout 1999. The latter (and possibly their own cultured broodstock) led to similar disease problems with TSV as in Taiwan Province of China in 2000. Despite these difficulties and drawbacks, the immense human and physical resources (and demand) in Mainland China led to their emergence as the world's leading producer of shrimp, in particular P. vannamei, during this decade (Wyban, 2002). Production levels in Mainland China of P. vannamei were approximately 270 000 metric tonnes in 2002, and they are expected to rise to 300 000 metric tonnes in 2003 (more than the rest of the world combined). This amount is 71 percent of China's total expected shrimp production of 415 000 metric tonnes in 2003 (Table 3).

Table 3: Production of all shrimp and P. vannamei in some Asian countries and the Pacific

Note: Sources of this information are from country correspondents and these figures are not official. All data for 2003 are estimates

Subsequently, P. vannamei, both SPF and SPF/SPR (for TSV) from USA, and non-SPF from Latin America and Taiwan Province of China/Mainland China have been introduced into many Asian countries including the Philippines (1997), Thailand (1998), Indonesia and Viet Nam (2000), Malaysia and India (2001) and Myanmar and Bangladesh, in some cases without official approval (Fegan, 2002; Taw et al., 2002; Wyban, 2002) (Table 2).

During the last three years, due primarily to the advantages of culturing P. vannamei and problems with the growth rate of P. monodon (which was the preferred species prior to that time), P. vannamei has gained prominence across Asia and production has increased significantly until 2003, particularly in Mainland China and Thailand. In 2004 this rate of increase slowed markedly and even declining as many farmers faced low farm gate prices and uncertain market access as a result of the anti-dumping case in the USA, which is one of the major importing markets.

Although difficult to estimate (due to the privacy of information of the commercial companies involved), with five to six commercial SPF broodstock suppliers in Hawaii and one in Florida, the USA's SPF P. vannamei broodstock industry is currently worth some US$ 5 000 000/year, the vast majority of which is now being exported to Asia. This equates to a figure of some 28 000 broodstock (14 000 females) per month, translating into a possible six billion nauplius and three billion PL/month. This number is sufficient for stocking 4 000 ha/month, itself capable of producing 24 000 metric tonnes/month, or 288 000 metric tonnes/year from the USA SPF P. vannamei broodstock alone.

Penaeus stylirostris is the major shrimp species cultured in Mexico, but has been replaced or out-competed by P. vannamei in every other country in the Americas. The SPF P. stylirostris have been promoted to many Asian countries during the past three years, but this species has only had a significant impact in Brunei, which has quadrupled its production since the importation of SPF P. stylirostris in 2000. Other trials in Taiwan Province of China, Myanmar, Indonesia and Singapore have been less successful and have not yet led to commercial culture operations in these countries/region (Table 2). Thailand and Mainland China also imported non-SPF P. stylirostris in 2000, but they have yet to make an impact on the shrimp production of either country.