目前美国的人工养鱼场越来越多,喂养的鱼不仅有淡水鱼,也有咸水海。去年,美国的养鱼场一共生产了4亿多公斤的鱼类产品,比10年前增加了3倍。据美国养鱼研究中心制订的计划,今后美国人工养鱼主要向以下三个方向发展:一是改进鱼饲料,既要低成本又能加快鱼类生长;二是培育不能繁殖的 At present, more and more artificial fish farms in the United States feed not only freshwater fish but also salty seawater. Last year, more than 400 million kilograms of fish products were produced in fish farms in the United States, a threefold increase from 10 years ago. According to the plan developed by the American Fish Research Center, in the future, artificial fish farming in the United States will mainly develop in the following three directions: First, to improve fish feed, it is necessary to reduce costs and speed up fish growth; second, to cultivate non-breeding