February 1, 2007
"Holding" Lobsters: Keeping the animals alive depends on water, bacteria and careful attention
by Sandra Dinsmore
"A lobster holding system is essentially a septic system." Most people would find that statement shocking, but Ronald Doane, 55, of Down East Sea Tanks, in Trenton, Maine, knows what he's talking about. For the last 13 years he has designed, engineered and built many lobster holding systems in the United States, systems inaccurately called inland pounds. In pounds, the lobsters are fed; in long term holding systems, they are not.
Lobsters with minimum blood protein levels of between 10 and 11 are held in chilled, constantly recirculating water tanks at temperatures far lower than ocean water. This re-supplies the lobsters with nutrients and oxygen and puts them into a kind of hibernation, which keeps them healthy until market conditions or holidays make them profitable to sell. (Blood protein levels, according to Robert Bayer, Ph.D., of the Lobster Institute, indicate strength, vigor, and shippability of the animals.)
There are three kinds of holding systems: a lobster pound is a small, natural or man-made cove enclosed at the ocean end to contain the animals. Poundkeepers hold and feed pounded lobsters. Tidal flow removes the waste.
What dealers refer to as a "tank house" is, essentially, a shallow swimming pool filled with ocean water that flows in and out. According to Doane, most tank house systems are float tanks, designed to "season" wild caught lobster before shipment. He explained that bait eaten by a lobster must pass through it before it can be shipped. If it is shipped by air unseasoned, it will die. A lobster kept in salt water without being fed will purge itself in a couple of days.
The tank house dealer keeps his lobsters loose in crates. He fills the crates according to shell quality and size. Lobsters kept in tidal pounds can stay healthy for months depending on whether the surface ices over, how lobsters are fed, and their quality or blood protein levels when put in. Because lobsters kept in tank houses are not fed, they stay healthy for only a short period. If a lobster's blood protein level goes below 10 parts per million (ppm), it will start to live on its body fat and become less healthy.
The method for holding lobsters in tanks for longer periods started about ten years ago in Canada, based on keeping them in individual PVC tubes or wire cages, removing waste products through biofiltration, and using chilled, aerated seawater to make them inactive.
Here in the U.S., only three or four people design and build long-term holding facilities with closed, recirculating tanks. Doane has his base, Down East Lobster Pound, a quarter mile past the Bar Harbor airport. Behind the fish market is his holding facility.
"These systems we build are biologically correct," he said. "All the specifications, all configurations are done on a pound [of lobster] per gallon [of water] ratio. You reach the optimum capacity for long term holding by making bio-filtration match water flow of gallons per minute, or gpm, by raising oxygen levels in the sea tanks."
Doane turned on the oxygenation, and within seconds, multiple circles of bubbling water exploded all over the surface of his tank. Almost immediately, bubbling water reached the crated animals.
He removes the waste product, or ammonia, from the water with raw Caribbean coral and dolomite, a mineral consisting of calcium magnesium carbonate found in quartz or marble mined in western Canada. Dolomite, a dull creamy white with an occasional glint of quartz, has a highly uneven surface that Doane refers to as erratic. Good bacteria attach to the surfaces of the coral, then spread and thrive on the dolomite, which "grows bacteria in all 360 degrees of the rock," Doane said.
Lobsters eliminate waste in the form of ammonia. Bacteria feed on the ammonia produced by the lobster waste. "A lobster system that works properly maintains a zero reading of ammonia with trace readings of nitrates and nitrites," Doane said. "The difference between a good lobster tank and a bad one is whether or not the system will process the ammonia in a 24-hour period."
One secret to long-term holding systems is the water. It must be chilled to a temperature that does not change when a load of lobsters is dumped in the tank. Doane accomplishes this through the use of what he called "massive, massive titanium chillers" that maintain 36- to 38-degree constant water temperature. The water goes through bio-filters before entering the tank. Dissolved oxygen, Doane said, "revitalizes and maintains the health of these animals." He said his liability insurance is high because he's ultimately responsible for the water quality in the tanks he sells and the way the customer maintains the system. He credits Michael Marceau, of The Lobster Company, in Kennebunkport, his mentor, for much of his success.
Among Doane's customers is Sterling Fitzhenry, of Cutler. Fitzhenry's tanks recirculate 50,000 gallons of water to keep his 50,000 lbs. of caged lobsters healthy.
Behind Fitzhenry's two tanks lies the filter. The pre-filter catches old foam, lobster legs and claw bands. On the bottom of the filter is a row of water pipes. Above them is a layer of thin mesh and 8 to 10 inches of dolomite. A filter pad lies on top of the rocks, and on top of that, the oxygen/air pipes. It's a sophisticated system, and expensive, but it keeps lobsters healthy.
Fitzhenry's two titanium chillers have their own building. In fact he built his compound as an investment composed of wharf, house, office building, tank house, two bait sheds, fuel shed, and a building for his son's welding business. Having run the business for three years, Fitzhenry has placed the compound on the market and plans semi-retirement. Of all who advised and helped him, Fitzhenry said that Doane "was the best thing, the best person that I was introduced to." He advised, "The key to keeping the lobsters alive is the bacteria."
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