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由于海洋中一些经济鱼类资源日益减少,以及各国200海里捕鱼区和经济区的划定,在一定程度上限制了海洋渔业的扩展。因此,大力发展鱼类养殖业,增加水产品产量就显得十分重要。目前,世界各国对鱼类养殖业都非常重视,产量稳步上升。据联合国粮农组织预计,到2000年,鱼类养殖产量将达到400万吨,比目前产量高四五倍。 目前,国外池塘养鱼产量水平较低,鱼产量仅为100—300公斤/公顷,放养面积仅为400—500万公顷。专家们认为,提高池塘养鱼产量主要有三个措施:扩大养殖面积、强化生
The reduction of some economic fish resources in the ocean and the delineation of 200-nautical-mile fishing areas and economic zones in various countries have limited the expansion of marine fisheries to a certain extent. Therefore, to develop the fish farming industry and increase the output of aquatic products is very important. At present, all countries in the world attach great importance to fish farming and their output has steadily risen. According to the UN Food and Agriculture Organization, it is estimated that by 2000 fish farming will reach 4 million tons, four or five times higher than the current output. At present, the production level of fish ponds in foreign ponds is relatively low, with fish yields of only 100-300 kg / ha and stocking areas of only 4-5 million hectares. Experts believe that there are three main measures to improve the fish production in ponds: to expand the area for breeding and to strengthen students