WELLFLEET — Oysters don’t hibernate, but when winter sets in and water temperatures dip below 48 degrees Fahrenheit, they enter something like a dormant state, which allows them to conserve energy. In the cold water of the harbor, the phytoplankton and algae they live on are in short supply, and they survive on glycogen, a stored form of glucose.

Now it’s time for the oysters to wake up from their winter naps and begin feeding on the nutrients the harbor offers them.
Most growers here remove their oysters from the water once temperatures begin to plummet and ice threatens to overtake the flats. They store them — the practice is called “pitting” — in cool, dark, humid conditions until spring. Surveying the flats on these longer, warmer days, you’ll see the farmers returning their bags of oysters to the tides.

In the past, oystermen simply stored their oysters in cave-like pits. But because the pits lacked climate control, the oysters were vulnerable to moisture loss, suffocation, or predation. Growers would lose half or more of their shellfish over the course of the winter. Aquaculturists today use cellars, walk-in refrigerators, or insulated containers where they can monitor and adjust conditions for their oysters through the season. The survival rate is 90 to 95 percent, particularly if the oysters are smaller and have yet to spawn.

To promote dormancy and prevent freezing or dehydration, growers try to keep the oysters between 34 and 45 degrees F and to maintain humidity between 85 and 95 percent. As with oyster farming, growers approach pitting in various ways. Mike DeVasto, who shares his grant on the west side of Field Point with his wife, Katie Murphy, relies on an insulated container with no mechanical refrigeration. He says he uses a thermostat and heat lamps if temperatures get too low.

Jason Weisman, who farms on Loagy Bay, stores his in a highly efficient refurbished U.S. Navy Polar King seamless cooler, designed specifically for outdoor use. He covers them with salt marsh hay and moving blankets that he keeps wet to retain moisture. Jim O’Connell, who was a mechanical engineer before he was an oysterman, built two below-ground pits that he controls with air-conditioning units and a system that returns moisture to the space.

In every case, the growers pay close attention to the thermometer. Ideally, they’ll move their shellfish from one environment to another with as little fluctuation in temperature as possible.

Back in the water, the oysters rehydrate, purge any impurities or sediments they may have accumulated, and feed. The Mass. Div. of Marine Fisheries requires that oysters spend 14 days on the tides before those that are large enough may be harvested. As the oysters settle into their spring routines, can summer be far behind?