A wide variety of animal and plant species are produced through aquaculture: finfish; shrimp, prawns and crabs; clams, oysters and mussels; as well as seaweeds and other aquatic plants.
Aquaculture provides nearly 50 percent, or 59.4 million tonnes (2004), of the annual world fisheries production of 120 million metric tonnes. Half of all aquaculture production is finfish, a quarter is aquatic plants and the remaining quarter is made up of crustacea (such as shrimp, prawns, crabs) and molluscs such as clams, oysters and mussels.
The species with the greatest production volume in 2004 was the Pacific cupped oyster (Crassostrea gigas) with 4.4 million tonnes, followed by three species of carps – silver carp (Hypophthalmichthys molitrix), grass carp (Ctenopharyngodon idellus) and common carp (Cyprinus carpio). In terms of ISSCAAP (International Standard Statistical Classification of Aquatic Animals and Plants) groups of species, by far the most production is in the group consisting of carps and other cyprinids. In addition to the three carps already mentioned, the bighead carp (Hypophthalmichthys nobilis) and the Crucian carp (Carassius carassius) also had production over 1.9 million tonnes in 2004. The top ten ISSCAAP species groups in terms of production are listed in Table 1.
Aquatic plants
As with aquaculture, the aquaculture of aquatic plants also showed significant increases from 2002-2004. In 2004, world aquaculture production of aquatic plants was 13.9 million tonnes, worth US$ 6.8 billion, of which China produced 10.7 million tonnes, valued US$ 5.1 billion. Other major producers were the Philippines with 1 205 000 tonnes, the Republic of Korea (547 000 tonnes), Japan (484 000 tonnes), the Democratic Republic of Korea (444 000 tonnes) and Indonesia (411 000 tonnes). The main species cultivated were Japanese kelp (Laminaria japonica – 4.5 million tonnes), Wakame (Undaria pinnatifida – 2.5 million tonnes) and Nori (Porphyra tenera – 1.4 million tonnes).
Species diversification
Over 240 different cultured aquatic animal and plant species were reported in 2004. This is an increase of 20 species from the figure reported in 2002 and demonstrates the increasing diversification currently taking place in aquaculture. These 240 species represent 94 families. Moreover, the diversity of species is probably under-estimated, as 8.9 million tonnes (15.1 percent) of global aquaculture production, including an additional 20 families, was not reported to species level in 2004, and this ‘unspecified’ group is likely to include species not yet recorded as being cultured. Of aquaculture reported to FAO to the species level, the top ten species account for 61.7 percent of the production, and the top 25 species account for 86.6 percent of total aquaculture production. These are less than the corresponding figures of 68.1 percent and 91.0 percent in 2000, providing another indication that species diversification in aquaculture is increasing.
There are more species of fish cultured than other major taxonomic groups. The cyprinids, with 18.2 million tonnes valued at US$16.3 billion, emerge as the most important taxonomic family by quantity and by total value. By volume, Ostreidae (oysters) are a distant second at 4.6 million tonnes and are followed closely by Laminariaceae (kelps) at 4.5 million tonnes. As can be seen in Figure 9, crustaceans represented by penaeid shrimps and grapsid crabs have total values that are disproportionately high relative to their quantities. While the penaeid shrimps rank sixth by quantity, they rank second by value. Similarly, grapsid crabs are 18th by quantity but rank 8th by value.
| Table 1: Top ten ISSCAAP species groups for aquaculture production of aquatic animals (not including aquatic plants) for 2004 | |||
| Production | Production % of world total | Value (billion US$) | |
| Species group | (tonnes) | ||
| Carps and other cyprinids | 18 303 847 | 40.3 | 16.4 |
| Oysters | 4 603 717 | 10.1 | 2.8 |
| Clams, cockles, arkshells | 4 116 839 | 9.1 | 3.3 |
| Miscellaneous freshwater fishes | 3 739 949 | 8.3 | 6.0 |
| Shrimps, prawns | 2 476 023 | 5.5 | 9.7 |
| Salmons, trouts, smelts | 1 978 109 | 4.4 | 6.6 |
| Mussels | 1 860 249 | 4.1 | 1.0 |
| Tilapias and other cichlids | 1 822 745 | 4.0 | 2.2 |
| Scallops, pectens | 1 166 756 | 2.6 | 1.7 |
| Miscellaneous marine molluscs | 1 065 191 | 2.3 | 0.6 |
| Other species | 4 334 931 | 9.5 | 12.9 |
| Total | 45 468 356 | 100.0% | 63.4 |