A laymans explanation:
The Canadian Copyright Act provides copyright owners with the sole and exclusive right to reproduce, perform or publish a work. In Canada, copyright protection exists as soon as a creation comes into existence. However, in order for a creation to be eligible for this protection it must meet the definition or a "work" under the Act. A "work" will be protected under the Act if it meets three criteria:
nationality of creator
Originality means you cannot have copied someone's work. Taking the same photograph that someone else has taken is not copying. Similar works can exist provided each photographer acted independently of the other. Ideas cannot be copyrighted.
Fixation is not defined in the Act but courts have determined the works must be in some material form, capable of identification, and have more or less permanent endurance. For instance a musical work must be printed. A photograph would have to be viewable or somehow published.
Nationality means you must be Canadian, British, or from one of countries under the Berne Convention.
Copyright protection is automatic in Canada. There is no need to register it, or mark it with a copyright symbol or watermark. Adding words like "all rights reserved" means nothing. Despite this, marking your work may help others who want to use the work to find the copyright owner and obtain permission. Or in court cases, eliminate the argument that they did not know a copyright existed.
The term of a copyright lasts for the remainder of the year that the photo was taken, plus a period of fifty years.
Finally, and of importance to people who use DA, the government has no enforcement role for the Act. Individuals must generally enforce their own rights through various remedies i.e.; suing or obtaining an injunction. The limitation on civil action is three years.
Or as a last resort (or maybe your only resort) you can spam the culprit with accusations of theft and get DA to ban them.... but that doesn't remedy the copyright violation: it just makes you feel better.