Rearing Oyster Seed

The larval cycle of the oyster can last between 10 to 20 days depending on the species. During these critical stages in hatchery processes, the environmental conditions in the hatchery are carefully controlled by highly skilled staff to meet the specific needs of the species being reared.

The broodstock are kept at sea and brought into the hatchery when they are needed for breeding purposes. Carefully selected broodstock are then conditioned to spawn. Once the eggs have been fertilised, they are placed in rearing tanks. The eggs need about 24 hours to be transformed into free-swimming larvae.

The larvae are placed in five-ton rearing tanks containing filtered, purified water kept at a constant temperature. They are fed microscopic algae daily. Every two or three days, the tanks are emptied, washed and disinfected. The larvae are filtered and sorted and put back into the clean tanks.

When the oyster larvae mature, suitable materials are added to the rearing tanks to encourage settlement and metamorphosis. Once the larvae have had a chance to attach firmly to the settlement material or ‘cultch’, the cultch can be placed out into the nursery system.


During this last stage in the hatchery rearing cycle, the spat is placed in upwellers and grow to approximately 4-5mm. The tanks used for spat rearing must be cleaned every day and the spat fed continuously. The nursery stage is the most demanding in terms of food requirements and rearing space.

Once developed the spat becomes ready for sale. To find out more about purchasing this high quality oyster seed please get in touch by going to our contact page.

What's on the menu

Tralee Bay Hatchery Co. grows the microalgae used to feed the broodstock and the larvae in a special lab on site. The algae room is separate from the hatchery’s other units because the culture conditions require rigorous controls. The seawater used in the production is filtered and purified beforehand. The air and water temperature must remain constant while the hatchery is in operation. The hatchery uses a modern LED lighting system to continuously expose the algae to light. Nutrient salts are added regularly to the culture medium.

Diatoms are cultured in the lab and in 12 outdoor diatom tanks capable of producing large volumes of diatom algae to support huge numbers of shellfish seed.