It was discovered that decrease of the number offish species was caused by a lot of factors, including water conservancy facilities construction, water pollution,over-fishing and illegal fishery.

• 鱼类物种资源的减少是多种因素造成的：水坝的修建使得鱼类栖息地环境改变从而导致鱼类的种类和种群数量变化，水污染、过度捕捞和非法渔业也在一定程度上破坏了鱼类物种多样性。