General Information Concerning the Terminology and Function of Equipment in the Oyster Hatchery
Picture taken from the entrance of the hatchery
My parents currently own and operate a successful twenty-something year old oyster farm which functions by buying young oyster seed, raising it to a mature oyster in suspended (enclosed) trays in the open waters of Discovery Bay, then selling the oysters to restaurants. The goal of building an oyster hatchery is to raise their own oyster seed and thus being able to supply their own farm with oyster seed and sell oyster seed to other shellfish farms.
We started off with one greenhouse in Sequim Bay, WA and several large fiberglass tanks. The general idea was to grow algae (a young oyster's favorite meal) in the big blue tanks and set up 'Upwellers' and 'Downwellers' in which we would grow oyster seed.
Screens inside an Upweller draining into a Downweller
The circular objects pictured in the white tank above are called the 'screens'. The bottom of the screens consist of a mesh that is just small enough that, when placed inside, the oyster seed will not fall out. The screens are being suspended in water inside the 'Upweller' (the white tank). The white tank drains out and into the blue tank behind it, the 'Downweller', via the filters (the white cylinder you can see at the top of the screens).
Screens holding oysters in an Upweller
Large Oyster Seed
This picture was taken from the entrance of the greenhouse. Excluding the network of pipes and pumps outside and a small office with an old microscope and a refrigerator full of shellfish diet, this picture shows pretty much everything there is to the hatchery.
There are three Upwellers on the deck to the right, and one Upweller on the small deck to the left. At the end of the summer, we added a fifth Upweller to the back of the greenhouse.
The blue tanks in the background of the picture are algae tanks. We pumped salt water from Sequim Bay through a series of three filters (to filter out barnacle larvae and other pesky little aquatic creatures) into the blue tanks. We then pumped oxygen into the tanks and let the water circulate and soak up the sunlight in order to grow algae.
The algae water we nurtured in the blue tanks was then pumped into the Downwellers. The Downwellers and Upwellers are connected via a small pump that is constantly moving water from the Downweller into the Upweller, which filters and drains back into the Downweller. As the water is being pumped from the Downweller and into the Upweller and then back into the Downweller, it passes by the oyster seed sitting in the screens suspended in the Upwellers.. As oysters are filter feeding bivalve mollusks, this is how oysters eat.
This entire process ultimately satisfies our goal of constantly circulating water and nutrients through the screens and maintaining an optimal environment for the oyster seed.