I'm not going to speak for the Canada Border Services Agency. What I'll say is that they're using a mix of tools, including all sorts of intelligence and working with other sorts of law enforcement in different countries. In terms of detection methods, you will find a lot of these drugs, including methamphetamines, being distributed through mail systems, so they would use things like X-rays and detector dogs, etc.
There are a number of different tools that border services officers use in trying to identify illicit shipments of drugs.