Development of mussel aquaculture in China.
Mussels are the main marine bivalves cultured in China. Mussel culture began in the 1970s and rapidly developed in the early 1980s when farmers mastered the technologies of breeding, seed collection and longline culture. Due to the low economic value of mussels compared with oyster, scallop and shrimps, the development of the industry began to slow down in the early 1990s. More than 50 species of mussels are found along the coast of China. The most important species being cultured are the blue mussel, Mytilus galloprovincialis, the green mussel Perna viridis, and the thick shell mussel Mytilus coruscus. Mussels are cultured by three basic methods: rope culture, lantern net culture, and bottom culture. Rope culture is the most popular method. In 2000, the annual yield of cultured mussels in China was 534 thousand metric tonnes, about 6% of the total shellfish production in China. To maximize the economic and ecological benefit from marine culture, polyculture of mussels and macroalgae, especially with the kelp Laminaria japonica, has been developing in the north of China since the mid 1980s. At first, farmers merely increased the culture densities of both kelp and mussels in an effort to produce as much product as possible and the results were not as good as expected. By the mid 1990s results had greatly improved because strategies were refined using information from studies on the carrying capacity of the culture sites. During the spring and fall, large numbers of juvenile mussels foul the culture facilities of other species, blocking the mesh of lantern nets used to grow scallops and cages used for fish culture. The fouling negatively influences the growth and survival of these species, and the fouling of mussels on longlines increases the weight of the lines and thus the labour cost. How to control the fouling of mussels on marine culture facilities has been and still is a challenge for scientists and farmers in China.