Oysters

Oysters have been harvested in Canada for centuries but their farming began in the 1950s. Today, the majority of oysters sold are supplied by farmers. 
Increasingly, oyster culture has been moving to off-bottom systems that use floating rafts, buoys, and longlines to suspend the shellfish above the ocean floor. 
Multiple studies have shown individual oysters are capable of filtering up to 50 gallons of water per day, and thus oyster reefs can significantly improve water quality and clarity.