To carry out their grim census, Wade and colleagues used two standard method for measuring whale populations.
为了进行他们这项严峻的普查，韦德和他的同事用了两种标准方法来测量鲸鱼数量。
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But after reports that the method was prone to human errors and fraud, officials adopted camera trapping for the first time in 2006 during the previous census.