The pup, named Hercules, is less than five days old.
Aquarium staff say when he was rescued yesterday, he was lethargic, dehydrated, underweight and in need of close medical attention.
It's not clear how the harbor seal pup became separated from his mother, but staff say it’s not uncommon, especially during summer pupping season.
So far this year, the aquarium has taken in nearly 50 harbour seal pups.
Most rescued harbour seals stay with the Marine Mammal Rescue Centre for about two months before they are released back to the wild.