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Grand Isle Oyster Hatchery Marks 20 Years as Research Facility

Louisiana Sea Grant (LSG) marks 20 years of operating its oyster hatchery on Grand Isle in 2013. During those two decades, the facility has been destroyed by hurricanes twice, threatened by an oil spill, relocated once, and now awaits another relocation into a state-of-the-art building.

Photo: Photo: Oyster seed raised at an oyster nursery.

Oyster seed raised at an oyster nursery.

“Basically my goal over the last seven years has been, ‘Just keep the research focus going’,” said John Supan, LSG’s oyster specialist and hatchery director. “There were three recent summers where I did all my spawning at Auburn Shellfish Laboratory on Dauphin Island because our hatchery was a wreck from hurricanes. Then the 2010 season was ruined by the BP oil spill. But now we’re on a roll,” said Supan.

The hatchery was established in 1990 as a commercial operation when the natural production of oyster seed was down because of drought and low Mississippi River discharge. Gulf Shellfish Farms of Louisiana ran the facility at that time, and Supan, who was a young LSG Marine Extension agent, was loaned to them to manage the hatchery and help train oystermen in remote setting techniques.

By 1993, naturally occurring seed production had rebounded, thanks in part to a record rainfall, and the need for a commercial hatchery passed. That could have been the end of it, but when the commercial venture folded, Louisiana Sea Grant acquired the hatchery and retooled it into a research facility with Supan at the helm.

Photo: A diploid oyster (left) and a triploid oyster (right).

A diploid oyster (left) and a triploid oyster (right).

Most of Supan’s research has focused on developing a broodstock for producing triploid oysters – which have higher summertime meat yields. But he is also examining alternative oyster growing systems, including two off-bottom cultivation techniques.

One method, called a long-line system, uses mesh bags suspended in the water column on a cable attached to posts. The bags can be raised and lowered to protect oysters from predators, fouling and the effects of disasters like hurricanes. The other system, called OysterGro, is less infrastructure intensive. It uses floating metal cages attached to pontoons.

“The systems we’re looking at are commercially used in other parts of the world,” said Supan. “People are making money with them, and they’re recovering more of the oysters they put in the water. One of my former grad students conducted an industry survey and found on average only 35 percent of the oysters planted using traditional methods make it to harvest. With off-bottom culture, every oyster you put into the water you get back.”

The alternative oyster culture research is conducted at the hatchery’s demonstration farm, located adjacent to a new operations center which opened in 2012 to replace a building lost during Hurricane Katrina. The operations center provides a farm service area downstairs, and upstairs living and office space for Supan and his graduate students.

Hatchery functions moved to the Louisiana Department of Wildlife and Fisheries’ (LDWF) Grand Isle Fisheries Laboratory in 2009 after being destroyed a second time. In 2005, Hurricane Katrina devastated the hatchery. Supan rebuilt, but the hatchery was razed again in 2008 by Hurricane Gustav. Construction on a new $3 million permanent facility is scheduled to begin later this year, with hopes of moving-in during 2013-14.

The new hatchery is being funded with money from a Natural Resource Damage Assessment (NRDA) grant for projects identified as helping speed recovery following the 2010 BP oil spill. The new facility will help Supan’s team remain at the cutting edge with state-of-the-art equipment for algal production, water filtration and even a seawater heater allowing the hatchery to extend its larval production beyond the current May-to-September season. The new hatchery also will be able to continue running essential equipment during tropical storms, with reduced hurricane preparation and recovery times.

The seawater heater will help Supan produce more than one billion larvae annually. Some of those larvae can be used to supply commercial oyster farmers with seed through a nearly-completed agreement between Louisiana State University and the Louisiana Oyster Dealers and Growers Association. Supan also plans workshops for oyster growers interested in setting up their own shore-side nurseries to cultivate seed.

Through an agreement with LDWF, the hatchery will supply half of its larval production to the state for setting in public waters. In return, Supan receives $210,000 annually that has allowed him to hire two full-time research associates. He hopes to add a third this year.

But what sets the hatchery apart and makes it commercially appealing is its potential to produce the aforementioned triploid oysters. “For hatcheries to succeed in the Gulf, they’re going to have to produce something that nature can’t because they can’t compete during times of high natural oyster production,” said Supan.

Triploid oysters have three sets of chromosomes – unlike normal (diploid) oysters that have two – and triploids are sexually sterile. From June through November when diploid oysters are expending energy to spawn and shedding fat stores, triploid oysters remain meaty – creating a possible summer crop for Louisiana oyster growers.

Triploids can be created artificially in the lab by manipulating oyster chromosomes, which Supan has done, but that process is not 100 percent. However, chromosome manipulation can also be used to create tetraploid oysters, which have four sets of chromosomes and can sexually reproduce. When bred with diploid oysters, tetraploid oysters produce 100 percent triploid offspring. Supan’s goal is to create a broodstock line for annual triploid production.

“Alternative oyster culture and triploid production both hold promise, but I don’t see them as replacing traditional methods used by the Louisiana oyster industry,” said Supan. “Nonetheless, I do see them as augmenting natural oyster production and creating new markets for growers and harvesters.”