Perhaps there is an overpopulation of seals in Canada. In the state of Wisconsin there was an overpopulation of white tailed deer and many animals were suffering from SWS (Sudden Wasting Syndrome) a parasite spread when there is an overpopulation event. The DNR flew over in helicoptors low to the ground and shot certain deer showing signs of the illness in the head or heart killing them instantly. If seal overpopulation is such an issue in Canada why doesn't the government there adopt similar methods for a more humane culling of a problem animal.
I don't know where you found this information but that is not what happened at all. The state of Wisconsin had hunters shoot ALL the deer in the areas where chronic wasting disease was found.
Exactly how a DNR guy could identify signs of chronic wasting from a helicopter is beyond me.