How fast oysters grow

The baby oysters remove excess nitrogen and carbon based nutrients from the water thereby improving water quality and clarity. This is actually a nitrogen and carbon negative process. Truly amazing! Oysters, like any animal, grow at different rates. So we have to separate the fast growers from the slow growers. We do this because the varying sizes of the oysters in the upweller create a compact mass with very little nooks and crannies for water to seep in and flow over the oysters.

This compaction slows the rate of growth, so we separate them out to silos with homogenous seed sizes to maximize the rate of water flow.

The oyster life cycle very much dictates the growing schedule on a farm. It takes 18 to 24 months for oysters to become adults or grow to market size, approximately 3 inches. Since growers only have a finite amount of land, they also only have a finite amount of oysters they can grow on their farm. Some of that area has to be devoted to oysters that are maturing to market size. Very much like agricultural farming, growers have to plan their farming schedule to allot enough time for growout.

Lately, oyster supply has been really tight and in New England, much of it is due to the growing cycle. Most New England growers receive their oyster spat in late April or May when the waters are warmer and contain more food. Starting baby oysters in the winter would annihilate them.

As mentioned above, it takes at least 18 months to grow an oyster to 3 inches, so if you count 18 months from April, the oysters will be ready the next October as summarized below.

Many growers are close or already out of market size oysters from the crop. Those oysters were sold last fall. Now, growers are waiting on oysters to sell from the crop, and unfortunately, the late spring this year gave these oysters a slow start. The eggs and sperm will encounter each other in the water, begin the fertilization process, and drift away from the spawning grounds in the water currents. Fertilized eggs drift in the water column undergoing cell division until they become juvenile larvae.

Oyster larvae will live in the water column for the next two weeks maturing through different stages. Larvae swim in the water currents in order to follow the phytoplankton, their source of food. Larvae are not capable of swimming horizontally, but they can move vertically to some extent. Once the larvae are approximately two weeks old and in the pediveliger stage larva with a foot , they begin to concentrate at the bottom of the river system to search for a hard substrate.

The larvae utilize an appendage that they grow called a foot. Fertilization takes place within minutes and cell division occurs over the next 24 hours. As many as million fertilized eggs are introduced to 1,gallon tanks in our rearing room. The larvae are voracious eaters. And we feed them well. Four to eight times a day with different algae grown in our mass culture room.

In two to three weeks, the larvae develop an eye-spot, a sign that they are ready to latch on to a substrate. Moved outdoors to our downwelling system at the Fishing Creek or Crocheron hatchery, the eyed-larvae are given ambient water with hatchery grown algae and finely ground oyster shell called micro-cultch.

Once settled and attached to this substrate, within 24 hours they undergo metamorphosis and become seed.