November 7, 2012 | Melonie Magruder

John Davis, owner and CEO of Carlsbad Aquafarm in California, believes that his business model will not only save the planet’s oceans, but that it will also provide future generations with the opportunity to enjoy fresh, delicious shellfish at a time when wild-caught shellfish from local waters is degraded by pollution and their numbers decimated by over-fishing.

For 20 years now, Carlsbad Aquafarm has raised mussels, clams, oysters and brine shrimp in a modest warehouse facility tucked up to the shores of Agua Hedionda Lagoon in North County San Diego. Jet skiers and water sports enthusiasts are within shouting distance of the quiet shellfish nursery. Davis leases his six-acre aquafarm from San Diego Gas and Electric, owner of the Encina Power Plant, and their relationship is symbiotic.

The power plant sucks in water from the ocean right at the mouth of the lagoon to cool its boilers and then discharges the water back into the Pacific. The slightly warmer water attracts sea lions, sharks, sea turtles and multitudes of fish. And it’s right where Davis parks his seaweed culture bins.

“I used to walk the shores around Balboa and dig up clams that were delicious,” Davis, a retired naval and commercial pilot, said. “Now, there is too much pollution being dumped into the ocean, even with all kinds of state restrictions. You have campers dumping waste, sewage spills, watershed effluent, demoic poisoning. It’s affected all the shellfish up and down the coast. Sure, our mussels grow in the same ocean that’s been contaminated, but our shellfish has been purified.”

That process is a painstaking filtration and treatment system called depuration. Harvested shellfish (mussels take 10 months to reach harvest maturity) are dumped into a series of tanks treated with ultraviolet light and oxygen to kill any bacteria. The shellfish rest in the sterilized water – tested daily for bacteria – for 44 days and are allowed to flush out any sand or other foreign matter.

The company then sends samples of harvested batches to a lab in San Diego to test for bacteria like fecal coliform and demoic acid. When they get the “all clear” report from the state, they pack up bags of the shellfish to ship all over the country. Each batch is tagged with Carlsbad Aquafarm’s identification and vendors retain the tags for 90 days, an extra precaution to track any bad batches. Davis says he hasn’t had any of those.

 “You can still find wild harvest mussels in harbors all around here,” Davis said. “But there’s a pretty high probability that they’re pathogenic. The farmed mussels I produce are the same animal, they just have been through a purification process so you can be confident that what you eat is not only sweet and delicious, it won’t make you sick.”

To Davis, the benefit is not only a healthier shellfish, but one less animal taken from the wild. In California, local waters have been home to commercial fishermen for centuries. As human populations have exploded up and down the coast, ocean beds have been so depleted of fish, sea urchins and shellfish that the California Department of Fish & Game began mandating Marine Protected Areas, to public outcry from commercial and recreational fishermen.

“Our cultured product gives back to the ocean,” Davis said. “We’re doing nothing more than farming. Just in water. You can think of our floating seed mussel lines like tomatoes growing on a vine.”

The seed mussels are attached like tiny specks to 10-foot long lines that float downward from a buoy, stretched out in 150-foot long lines on the surface (clams are grown in trays). They feed on micro algae and are protected from predators with mesh sleeves. Because the lagoon was dredged long ago, the aquafarm essentially constitutes a living reef to attract a rich marine population of lobsters, squid and other fish.

“Our operation enhances the marine environment,” Davis said. “The value of that enhancement is greater than the product we sell.”

More than 91 percent of seafood consumed in the U.S. is imported. Aquaculture provides more than 50 percent of the world’s seafood.

Kim Thompson represents the Long Beach Aquarium of the Pacific’s Seafood for the Future program. They partner with local chefs to help them find vendors of farmed seafood that provide restaurants with a healthier product that preserves wild marine life.

“To feed tomorrow’s population, aquaculture is essential,” Thompson said. “We help our restaurant partners who want sustainably raised seafood find the good suppliers, like Carlsbad Aquafarm. You want a provider that takes active steps to minimize their impact on surrounding ecosystems.”

Despite the regulatory environment (Davis says he deals with 11 different agencies alone), Carlsbad Aquafarm has grown to where they are a significant supplier of shellfish to restaurants around the country. Working with his son and some 20 employees, they can harvest 40,000 pounds of mussels a month and 6,000 dozen oysters a week. Without, Davis points out, any of the government subsidies that the agricultural industry enjoys.

“We have a company that would like us to supply four million oysters,” Davis said. “That’s a huge physical job, but it’s something to shoot for. Aquaculture is a way for me to give back to the ocean. Because the ocean has always given to me.”