A prize is not income, in general. According to the Government of Canada,
When the prize has been received as a gift, it is not included in computing income at the time of receipt. However, the recipient will be deemed to have acquired the prize at its fair market value pursuant to paragraph 69(1)(c), so that a subsequent disposition of the prize will result in a capital gain on any increase in value since the time of its acquisition. A prize can be reasonably considered to be a gift from the viewpoint of the recipient, even though chance and/or skill may have been involved in the win. Ordinarily a gift is not considered to have been made until the donee has received delivery of the gift and accepted it in a completed and irreversible transaction.
If the prize was from your employer, or you support yourself by entering and winning hackathons (I once knew a professional bridge player) it might be taxable -- you can read the rest of the page for more details on that.
Note to Americans: I am aware you pay taxes on game show winnings etc. Different countries have different tax laws.