Because academic research on the humpback dolphins only began five years ago, there are no records to indicate whether the total population has been decreasing year by year, but based on comprehensive reviews of overseas research and other data, environmentalists generally agree that the current population is a lot lower than in the past.
由於學界近 5 年才對白海豚有較詳盡的調查，無從比對分析族群量是否逐年減少；而早期麥寮（1991 年動工）、彰濱（1979 開工後停擺，1992 復工）、台中港工業區（1990 年代）開發時也未做相關調查，但綜合國外研究和其他數據比對下，保育界一般認為目前族群數量理應比以前「少了很多」。