CHINA

The production from the Chinese bivalve aquaculture industry in 1986 totalled 794,539 MT (FAO, 1988). Table 1 shows the most important bivalve species along with their annual culture production values from 1983 to 1986. The total production of these species in 1986 was 605,896 MT. This accounted for over 76% of the total bivalve mariculture production in 1986 (Fig. 1).

In terms of quantity, the common mussel Mytilus edulis is the most important species cultured along the coast of China. Production in 1980 amounted to 67,200 MT and 210,659 MT in 1986 with an average annual growth rate of 23%. The increase in mussel landings is mainly due to the adoption of more intensive culture systems such as the hanging culture method. Other species of mussels cultured in China are the black mussel M. crassitesta and the green mussel P. viridis.
The razor clam, Sinonovacula constricta is also an important cultured species. Landings from this species have increased steadily from 1983 to 1986 with a production of 126,175 MT and an average annual growth rate of about 13%.
Several species of edible oysters are found in Chinese coastal waters, however only Crassostrea plicatula and C. rivularis are cultured on a large commercial scale (Lovatelli, 1988). Small scale culture of C. gigas is practiced in Liaodong and Shandong peninsulas. The other two species are mainly cultured in Fujian and Zhejiang (C. plicatula) and in Guangdong (C. rivularis). Oyster production data are available from 1983 (Table 1). There has been an average annual growth rate of about 16% from 1983 to 1986 with the highest growth rate of 25% registered in 1984 to 1985.
The blood cockle Anadara granosa is one of the major cultivated species in Shandong, Zhejiang, Fujian, and Guangdong provinces. Cockle production in 1985 amounted to 83,430 MT. However, in the last decade its culture has been declining mostly because of severe changes in the conditions of the coastal mud flats. Much of the traditionally productive areas for seed rearing have been lost, which in turn has lead to a shortage of seed supply.
The ark shell. Scapharca subcrenata is also an important species cultured in China. Production output has been increasing since 1983 with the highest annual production of 24,173 MT in 1986 and an average annual growth rate of 30% since 1983.
Production of the hard clam Meretrix has been increasing since the early 1980's with a production of 41,603 MT in 1986 and an average annual growth rate of 41% since 1983. This species is broadly distributed along the coast of China in fine sand beaches.
The most important species of scallop in China is Chlamys farreri which occurs naturally in Liaodong and Shandong peninsulas. Scallop culture in China began only during the late 1970's, however it has developed rapidly. The landings of C. farreri in 1982 amounted to 1,162 MT while it increased to 23,686 MT in 1986 with an average annual growth rate of 116%. Other species of scallops cultured are C. nobilis, Pactinopecten vessoensis and Argopecten irradians.

Table 1: Annual production of commercially important shellfish in China, 1980–1986. (Values: MT).

* The production figures indicated for the mussel, scallop, razor clam are with shell-on; figures for the hard clam,ark shell and oyster are fresh meat.
A = Production value assumed as constant at year 1984.
B = Production value assumed as constant at year 1985.

Figure 1. Total annual mariculture production of the most commercially important bivalve species in China from 1983 to 1986.

Figure 2. Total production figures for the periods 1983–1984 and 1985–1986 of the major bivalve species in China.

The other important bivalve species include the pearl oyster, Pteria (Pinctada) martensis and the short-necked clam Ruditapes philippinarum. Although the artificial culture of the pearl oyster is relatively recent, considerable achievements have been made in the artificial rearing of spat, culture of adults, techniques for inducing pearl formation and the direct utilization of pearl nacreous substance. The short-necked clam occurs mainly in muddy intertidal zones along the coast of China. Although the natural stocks are abundant in some areas of the Liaodong and Shandong peninsulas and in Fujian, one major constraint to increasing the production is the limited area available for its culture.

Figure 2 shows the production figures of the most important bivalve species cultured in China for the periods 1983–1984 and 1985–1986. The cumulative output during the second period increased for all species, indicating a strong development in the industry and potential for further expansion. The production percentages of the species indicated in Table 1 from their total production for the two periods are shown in Figure 3. For some species, like A. granosa and S. constricta the percentages declined, although their absolute productive values increased, mainly because the share of C. farreri in the total output jumped from 0.8 to 3.2%.

Table 2 summarizes a number of information on the present status of mollusc culture in China. Although the seedlings for all the cultured species are obtained from the wild, artificial spat propagation for some species is becoming the major source of seed supply. The bulk of scallop spat production as well as abalone juveniles are hatchery produced. These artificial rearing techniques are relatively well developed, however for some species artificial propagation is still on a small scale.
The culture of clams in China is practiced exclusively in the bottom of intertidal areas, whereas the suspension culture method is becoming increasingly important for the culture of scallops, oysters and abalones.
Molluscs are highly valued in China and domestic consumption, especially along coastal communities, is high. However, a number of species such as scallops, abalones, hard clams, oysters and pearl oysters have well established export markets.
The culture status of all species mentioned throughout is relatively well developed, with the exception of the Japanese scallop, P. yessoensis which has been recently introduced in the country.

The major constraints to the shellfish industry in China range from limited seed supply for some species such as A. granosa and M. meretrix to limited suitable culture areas for other species such as C. plicatula, R. philippinarum and S. constricta/
There are more than ten institutes in China involved in mariculture research and most of them are carrying out some research to improve the mollusc industry.
At present considerable efforts are being channelled into artificial propagation techniques, improving on-growing practices as well as adopting new culture methods altogether.

Figure 3. Comparative production percentages of the major bivalve species cultured in China for the periods 1983– 1984 (A) and 1985–1986 (B).

Table 2: Information on status of mollusc culture in China.