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根据1970年1月1日的统计,美国约有年平均水面在202公顷(3030亩)以上的水库1,20坐,总面积358万公顷(5370万亩)按大小分:202—810公顷的坐数占52%,但仅占总面积的15%;810—2,025公顷的304坐;,025—4,050公顷的130坐;4,050—10,00公顷的115坐;10,000公顷以上的75坐。970年美国水库(以面积370万公顷计)的游钓渔获量估计为9,000万公斤。鱼业管理人员常常采取某些特殊的措施来改良水体或增殖鱼类资沅以提高产量,但只有在一系列措施协调地进行时,才能获得成功。如果能够比较精确地予计各种不同的环境变量对产量的影响,就可能大大地改进管理技术。国家水库研究计划的一项主要任务,是
According to the statistics of January 1, 1970, the United States has about 1,20-seat water reservoirs with an annual average surface area above 202 hectares (3030 mu) and a total area of 3.58 million hectares (53.7 million hectares) by size: 202-810 hectares Occupying 52% of the total, but only 15% of the total area; 304 sitting on 810-2,025 hectares; 130 sittings on 025-4,050 hectares; 115 sittings on 4,050-10,00 hectares; 75 sitting sitting above 10,000 hectares. The catch of the United States reservoirs (covering 3.7 million hectares) in 970 was estimated at 90 million kilograms. Fish industry managers often take special measures to improve water quality or raise fish stocks to increase yields, but only if a series of measures are coordinated can they be successful. If you can more accurately predict the impact of different environmental variables on production, it is possible to significantly improve management techniques. One of the major tasks of the National Reservoir Research Program is