In terms of systematic tracking of temporary foreign workers once they're in Canada, there is no one single mechanism that is in place to be able to track the movements of temporary foreign workers or what may happen to them. In fact, that's why we've put forward these promotional brochures for applicants to be aware of how they can help themselves, by contacting the relevant provincial authorities if they run into a difficulty.
With regard to Mexicans, I'm not aware of people coming in without proper documentation. As part of the screening process, Mexican workers don't require a visa to enter Canada, but if they intend to work, they do require a work permit, and if they intend to be here for more than six months, they need to do a medical examination.