There are a variety of crabs that present a problem to the oyster industry as well, including the Mud Crab, the Rock Crab and most recently the European Green Crab. These predators cause a great deal of damage to oysters due to the great numbers of them. They gain access to the oyster by piercing the softest part of the shell – the area where which it is attached to the cultch. These predators eat a significant amount of small oysters but are unable to gain entry to shells more than 30 milimetres in length because the shells become to strong to enter.. Many oyster farmers remove crabs with traps or simply grow their young oysters out of their reach by floating them just under the surface of the water.
Other threats to oysters come in the form of “boring” predators, such as the snails. These small but effective pests actually bore tiny holes in the oyster’s shell until it is penetrated. Once the hole is made, the oyster dies and is ingested. Though they pose a small problem to the industry, they can still do significant damage if the numbers are great enough.
Another threat to the oyster comes not in the form of a sea animal, but rather a plant, known as the “Oyster Thief.” This algae attaches itself to oyster shells that are at between a half to one and a half metres deep. When the tide falls, the algae is filled with air. When the tide returns, the air-filled plant rises to the surface taking the oyster with it. The plant and the oyster are then at the mercy of the tide and current and are usually taken out to deep water where the oyster will not reproduce.
The oyster and the industry are under attack by many foes on many fronts, including pests, diseases and illegal fishing, as well as farm and industrial run-off into the streams and estuaries where the valuable resource is grown. There is a great deal of work and countless individuals involved in the continual battle to remain ahead of all the possible problems that could arise as a result of any of these pests or problems getting out of hand. It involves a balancing act that juggles and uses limited resources to do as much as possible to ensure the security and longevity of the oyster industry on Prince Edward Island.