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Prevention of Aquaculture Pollution Using Seaweeds
- Hong Kong University Press, HKU
- Chapter
- Additional Information
Perspectives on Marine Environment Change in Hong Kong and Southern China, 1977-2001 (ed . B. Morton). Proceedings o f a n Internationa l Worksho p Reunio n Conference, Hon g Kon g 21-26 October 2001. Hong Kong: Hong Kon g University Press , 2003. PREVENTION O F AQUACULTURE POLLUTIO N USING SEAWEED S C. K . Tsen g Institute of Oceanology, Chines e Academy o f Sciences, Qingdao 266071 , Chin a ABSTRACT Marine pollution recently has become more and more serious in China. With the rapid growth and development of aquaculture, China is now the World's leading aquacultur e country. In 1999, mariculture production in China reached 9.7 million tonnes, comprising 8 million tonnes of molluscs, 1. 1 million tonnes of seaweeds and 0.6 million tonnes of fish and crustaceans. Marine pollution arising from aquacultur e activities has, however, become a more seriou s problem . Ecologica l aquacultur e growin g economi c seaweed s in conjunctio n wit h culture d animal s i s considere d t o b e a n effectiv e wa y t o reduc e pollution. Economic seaweeds such as Laminaria, Undaria, Sargassum, Gracilaria and Porphyra ar e considered t o be suitable species for ecologica l aquaculture . INTRODUCTION Mankind is now facing thre e important problems, an increasing population, a depletion of resources and a worsening environment. To control its population growth, China has implemented the national policy of birth control with a view to stablising the population in twenty to thirty years at 1.6 billion. Resources in China have been seriously depleted and lan d fo r agricultur e i s decreasin g steadily . In Novembe r 2000 , Mr . Yan g Jian , Director of the Bureau of Fisheries, China, announced that in 1999 China's aquacultur e production ha d reached 58 % of total fishery productio n an d it is now the first countr y in the world with an aquaculture production whic h exceeds that of the capture fishery . In 2000, aquaculture in Chin a advance d on e ste p more, reaching 60 % of total fisher y production. Thus, aquaculture is now an important industry i n China. A worsening environmen t i s becoming th e most important proble m i n China. O n land, tree planting has been adopted a s a policy to protect the environment. In the sea, 538 CK. TSENG several measures have been proposed. In Norway, where more than 40 thousand tonnes of salmon ar e produced an d exported annually , unused feed an d metabolic products at the bottom of the cultivation cages are sucked out and laid on the land a s fertilizer fo r crops and trees. This measure removes the nitrogenous and phosphorus pollution but it does not remove the carbon dioxide exhaled by the cultivated fish. Therefore, cultivatin g seaweeds wit h cultured fis h an d other animals is considered t o be the best method fo r preventing marin e pollution resulting from aquacultur e industries . AQUACULTURE I N CHIN A Aquaculture i n Chin a ha s a long histor y o f abou t 300 0 years . Aquacultur e starte d i n China with freshwater fish . Fish farmers at that time caught fish fingerlings fro m rivers, and grew them in ponds. After years of investigation, fish farmers finally cultivate d fou r kinds o f fish , th e Blac k carp , Gras s carp , Silve r car p an d Bi g Hea d carp . The y ar e collectively known as the 'famil y fish' . Chines e people accepted the ancient method of family fish cultivation for many years until the early 1960s . The second oldest cultivated animals ar e probabl y oyster s i n Fujia n an d Guangdon g Provinces , th e cultivatio n o f which starte d severa l hundre d year s ago . Bambo o stick s an d stone s wer e plante d i n estuaries where oysters grow (cultch) seed will naturally attach to such artificial substrat a and grow to marketable size . The planters then harvested the oysters for th e market. The seaweeds Porphyra, commonl y known as the purple laver or Zicai in Chinese and Nori i n Japanese, an d Gloiopeltis, commonl y know n a s the glueweed o r Hailo i n Chinese, were grown o n rocks in the natural habitat by cleaning th e surface a t certai n...