In 1993 an epidemic outburst of viral disease in 2 . 2 million mu of pond - cultured shrimp brought about a great decline in production in spite of much ameliorative measure taken to improve culture mode and culture technology 1993年，全国范围内220万亩的对虾养殖池爆发了病毒性流行病，产量大减。近几年来，尽管对养殖模式、养殖技术等进行了改革，但我国北方中国对虾的养殖仍然处于低迷状态。
Duck from mai po found in russia a first - winter female northern pintail that was trapped and ringed in the waterfowl collection at mai po nature reserve on 6 february 2002 was found shot near lake khanka near vladivostock , ussr on 5 april 2002 . the distance the duck had flown was 3 , 030 km 2002年2月6日，一头首次飞抵米埔的雌性针尾鸭在水禽养殖池被加上环志，并于2002年4月5日在俄国沃斯多克邻近的简卡湖音译附近出现，当时身上中枪，它一共飞行了3 , 030公里。
Because there are a great quantity ' s heterotrophic bacteria in the breeding pool , which will have the repulsion action to the insufficient quantity ' s nitrifier and prevent the nitrification , the situation will bring the accumulating of nitrite which is the middle substance of nitrification in water , the long term accumulated nitrite can debase fish and shrimp ' s disease - resistant and decrease the growth and even die 由于养殖池中存在大量的异养菌，受到异养性细菌排斥，本身无足够数量的硝化菌，硝化作用往往受阻，结果就会引起硝化作用的中间产物亚硝酸盐在水体内的累积、亚硝酸盐长期蓄积会使鱼虾等抗病力降低、生长受阻、严重者中毒死亡。
