The life cycle of the Atlantic Oyster, which is more commonly known as the Malpeque Oyster, goes from being a very active larva to the very sedentary life of a mature oyster. During the early summer, a mature female oysters can release millions of eggs and at the same time males can release an even greater number of sperm. The eggs are fertilized by sperm in the open water. These fertilized eggs develop into microscopic oyster larvae. The tiny larvae quickly develops a shell and the ability to swim and feed. They are very vulnerable at this stage. While spending about three weeks swimming and being moved around by currents and tides where most of them become the food supply for plankton-eating fish, including mature oysters. As little as one percent of the larvae live to reach the next stage of development.

At the end of the three weeks of swimming, the oyster will begin to seek a firm clean surface to attach itself and become what is known as spat. This marks the end of the oyster’s movement. For Read More

The life cycle of the Atlantic Oyster, which is more commonly known as the Malpeque Oyster, goes from being a very active larva to the very sedentary life of a mature oyster. During the early summer, a mature female oysters can release millions of eggs and at the same time males can release an even greater number of sperm. The eggs are fertilized by sperm in the open water. These fertilized eggs develop into microscopic oyster larvae. The tiny larvae quickly develops a shell and the ability to swim and feed. They are very vulnerable at this stage. While spending about three weeks swimming and being moved around by currents and tides where most of them become the food supply for plankton-eating fish, including mature oysters. As little as one percent of the larvae live to reach the next stage of development.

At the end of the three weeks of swimming, the oyster will begin to seek a firm clean surface to attach itself and become what is known as spat. This marks the end of the oyster’s movement. For the rest of its life it will remain attached to the initial material that it chose. This material is known as “Cultch.” Once the oyster finds appropriate cultch to attach to, they secrete a cement-like substance and will permanently attach themselves to whatever hard clean surface they found.


© Community Museum Association of Prince Edward Island, 2005. All rights reserved.

Drainage pipes used as spat collectors.

PEI Shellfish Museum

© PEI Shellfish Museum


Egg crates used as spat collector.

PEI Shellfish Museum

© PEI Shellfish Museum


Growth of the oyster

In PEI bays warm water temperatures trigger the release of sperm and eggs from mature oysters. Over four to six weeks, during the spawning season, the female releases millions of buoyant eggs – the male even more sperm. Fertilization takes place in open water for about three weeks. The larvae, about the size of a grain of pepper, drifts in tidal currents feeding on microscopic plankton.

While drifting it looks for something to attach to. These collectors, strung in the water during high and low tides, do very nicely but have to be removed from the water before the winter freeze up.

Community Museums Association of Prince Edward Island.

© Community Museum Association of Prince Edward Island, 2005. All rights reserved.


There are often dozens of spat that attach themselves to a small area that is suitable but as they grow, few of these will survive. As the oyster grows, so does its shell. The condition of the environment decides the shape that the oyster takes. Crowded conditions produce long narrow shells whereas open unrestricted conditions produce the higher quality round shells. Within four to six years the oyster will reach the three inches that’s required to make it a legal size for fishing.

The science and collection of spat is a huge part of the aquaculture industry and there have been many developments since the early 1900s. Modern day lease owners do their own spat collection and cultivation of their beds while much of the spat collection and growth of young oysters is done through the initiatives of the PEI Shellfish Association.

There are often dozens of spat that attach themselves to a small area that is suitable but as they grow, few of these will survive. As the oyster grows, so does its shell. The condition of the environment decides the shape that the oyster takes. Crowded conditions produce long narrow shells whereas open unrestricted conditions produce the higher quality round shells. Within four to six years the oyster will reach the three inches that’s required to make it a legal size for fishing.

The science and collection of spat is a huge part of the aquaculture industry and there have been many developments since the early 1900s. Modern day lease owners do their own spat collection and cultivation of their beds while much of the spat collection and growth of young oysters is done through the initiatives of the PEI Shellfish Association.


© Community Museum Association of Prince Edward Island, 2005. All rights reserved.

Workers preparing some equipment.

PEI Shellfish Museum

© PEI Shellfish Museum


Various shapes and colours of the Malpeque Oysters.

PEI Shellfish Museum

© PEI Shellfish Museum


Summerside harbour seen over a large deposit of oyster shells.

PEI Shellfish Museum

© PEI Shellfish Museum


Learning Objectives

The learner will:
  • describe the Oyster life cycle using terms like mature female, eggs, fertilization, larvae, growth, and fishing.

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