TAIWAN

According to the Taiwan Fisheries Bureau year books the annual total production of shellfish in Taiwan increased steadily from the early 1970's to a highest annual production of 43,856 MT in 1978. However, it decreased to 40,537 MT in 1980 mainly due to the reduction in hard clam (Meretrix lusoria) production. In 1980 the total shellfish culture landings (37,657 MT) contributed about 93% of the total production.
Total annual shellfish culture output from 1980 to 1986 is shown in Figure 1. Production from 1980 to 1984 increased from 37,657 MT to 50,693 MT with an average annual growth rate of 8%. However, landings dropped to 37,795 MT in 1986 mainly due to the reduction in oyster (Crassostrea gigas) and hard clam production (Table 1).

A number of bivalves and gastropods are cultured on a large scale in Taiwan. Table 1 show the most important shellfish species along with their annual culture production figures from 1980 to 1986.
The Pacific oyster C. gigas is the most important shellfish cultured in Taiwan. High mortality of this species occurred in the years 1974, 1975 and 1976 resulting in the reduction of oyster production. However, due to improved culture management and spatfall forecasting techniques, the industry recovered and output increased considerably during the first half of 1980 registering the highest annual production of 29,042 MT in 1984 and a 9% average annual growth rate from 1980. Oyster and other bivalve production dropped in 1985 and 1986 probably due to adverse environmental conditions such as water pollution and bad weather.
The hard clam M. lusoria is also an important species ranked second with a highest annual production of 17,322 MT in 1984 and an average annual growth rate of 29% from 1980. Such growth rate is mainly related to the development of hatchery and nursery techniques since the late 1970's. However, lower production figures were recorded in 1985 and 1986 due to high mortality in adults, juveniles and seedling which is probably related to water pollution.
Annual production of the short-necked clam Gomphina veneriformis in 1986 amounted to 3,436 MT. The annual output of this species has been in the range of 3,500 MT mainly due to the limited supply of seed.
The blood cockle Anadara granosa is a luxurious species, with a highest annual production of 132 MT in 1973 (Ting, 1984). However, its production gradually declined to only 7 MT in 1980 mainly due to shortage of seedlings. With the introduction of hatchery practices and importation of seed production in 1985 climbed to 10 MT.
The purple clam Soletellina diphos seedlings are collected with difficulty from the sand and stocked in culture ponds. The production of this clam during the 1970's was relatively unstable, however the output increased steadily from 1980 (136 MT) to 1986 (439 MT) with an average annual growth of 27%.
The freshwater clam Corbicula fluminea occurs in fish ponds and drainage canals. Due to its great demand and the construction of large numbers of ponds the production of freshwater clam reached 1,000 MT in 1974 and 6,354 MT in 1980.

Figure 1. Total annual production of commercially important shellfish in Taiwan from 1980 to 1986.

Figure 2. Total production figures for the periods 1981–1983 and 1984–1986 of the major shellfish species in Taiwan.

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

The Pacific oyster C. gigas, along with the hard clam M. lusoria and the short-necked G. veneriformis are the most important shellfish cultured in Taiwan. Their combined culture output in 1986 was 36,816 MT which accounted for over 97% of the country's entire shellfish production from aquaculture. The production figures for the above species along with the combined production of the other species for the periods 1981–1983 and 1984–1986 are shown in Figure 2. The cumulative output during the second period increased for all species, except the short-necked clam due to the limited seed supply, as mentioned above. The production percentages of the above species from total production for the two periods are shown in Figure 3. Among all the culture species, the hard clam shows the highest production output increase compared to the total, passing from 28.1% in the period 1980–1983 to 35.7% in the period 1984–1986. Similarly the cumulative culture landings of the other minor species has increased in recent years, passing from 1.1% in 1980–1983 to 1.5% in 1984–1986.

Table 2 summarizes a number of information on the status of mollusc culture in Taiwan. Seedlings of most of the cultured species have been obtained mostly from the wild, however due to the poor and/or insufficient recruitment of certain species, hatchery techniques have been developed to ensure a steady supply of seed. Artificial seed propagation of the hard clam, purple clam and abalone are relatively well established compared to the blood cockle which is still on an experimental stage.
Most bivalve species in Taiwan are bottom-cultured. However, due to the limited availability of suitable bottom culture areas and coastal water pollution, suspension culture practices are becoming more important especially in the culture of the Pacific oyster and abalone. For the strictly bottom dwelling species, such as the clams, the limited culture ground is the major constraint to their production expansion in the country.
The consumption of most shellfish cultured in Taiwan is domestic with the small abalone H. diversicolor being the only mollusc with a strong export market.
The culture status of all the species mentioned is relatively well developed with the exception of the blood cockle, A. granosa which is still considered to be experimental.

The major constraints to Taiwan's shellfish industry is the limited supply of seedling from the wild, overfishing and water pollution. For the industry to expand in the near future, Taiwan must now increase the culture area especially in coastal areas and protect natural resources in order to ensure a reliable supply of seed. In addition, artificial propagation techniques as well as water pollution control measurements are two major topics which are receiving considerable attention.

Figure 3. Comparative production percentages of major shellfish species in Taiwan for the periods 1981–1983 (A) and 1984–1986 (B).

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