When entering Canada, can Canadian citizens declare another nationality without mentioning their Canadian citizenship?

Question

On the plane, someone in the family near me couldn't find their Canadian passport. She left it in Vietnam, and forgot to bring it on the plane. She said they have dual citizenship of Vietnam. Family suggested she enters Canada customs with just their Vietnam passport. But don't say anything about Canadian passport or forgetting it!

My first question, are Canadians mandated to disclose their nationality when entering Canada?

Second, what happens if Canada customs officer finds out this Vietnamese didn't disclose? What's maximum fine, penalty?

Answer 1

Officially, the government wants you to use your Canadian passport:

Canadian citizens, including dual citizens, cannot apply for an eTA to enter Canada. You will need a valid Canadian passport to board your flight to Canada.

And on another page:

Dual Canadian citizens can no longer travel to or transit through Canada by air with a non-Canadian passport. You need a valid Canadian passport to board your flight.

(That page also includes what to do if you don't have your Canadian passport and don't have time to get one before you travel.)

That said, I know a person whose Canadian passport had expired and who had a valid British passport. She applied for and got an ETA and entered as a British person without mentioning that she also was a Canadian citizen. I don't know what would have happened if immigration had become aware of her dual citizenship, and wouldn't recommend this action to anyone else.

Since everyone needs either a visitor visa or an ETA, I don't know how your plane mate got on the plane without their Canadian passport, and I don't know how they expected to be admitted.