Selecting a Better Oyster (Part 2): Back from the Brink

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Selecting a Better Oyster (Part 2): Back from the Brink

Bringing oysters and industry back after almost a century of disease decimated wild populations was part science, part serendipity.

Oyster Aquaculture: Researchers sort oysters for a study about breeding disease resistance. ©Will Sweatt/2012

Researchers sort oysters for a study about breeding disease resistance. ©Will Sweatt/2012

By Janet Krenn

Part 2 in a 3-part series: Selecting a Better Oyster.

Today, Virginia’s aquaculture industry has a $14.3 million economic impact to the state. Not bad for an industry that emerged less than 10 years ago, when science and serendipity collided.

On the simplest level, growing oysters is like growing vegetables. Growers take seed, fingernail-sized oysters, and plant them in the water where they mature. Just as agriculture sprang up out of the need to have ready access to food, in some ways, so did oyster aquaculture.

Through the 1900s a series of diseases decimated wild oyster populations in Chesapeake Bay. Harvests of wild oysters dropped from historical highs of more than 100 million pounds annually to less than 5 million by the 1990s.

With wild oysters struggling, the oyster industry and oyster restoration groups started looking for ways to introduce disease-resistant oysters into the Bay.

In the late 1990s, the state legislature got involved and put forth funding for VIMS to work on oysters. Stan Allen was hired to start and lead a new center.

“It didn’t even have a name when I got here,” Allen said. “I was the one who decided to call it the Aquaculture Genetics and Breeding Technology Center.  I figured the name would cover everything that we might have to do, whatever that was.”

Oyster Aquaculture: Stan Allen takes a microscopic view on oysters. ©Margaret Pizer/VASG

Stan Allen takes a microscopic view on oysters. ©Margaret Pizer/VASG

If it sounds like starting from scratch, Allen says that’s because it was. The state didn’t stipulate what direction ABC should go. “The general directive was to do something about the oyster problem,” Allen says, and that included restoring oyster reefs and bolstering a struggling industry.

Back when Allen was in graduate school in the late-1970s, disease resistance wasn’t at the top of his mind. He wanted to breed a “value added” oyster. He planned to make a triploid that would have three sets of genes instead of two. The odd number of genes would keep the animal from reproducing. Without the need to divert energy to reproduction, the oyster could focus on growth and produce more meat more quickly.

Twenty years later, Allen had been successful in producing triploids, in not one, but three species of oyster. As he moved from east coast to west coast and back again, he developed procedures to commercialize triploid production in Virginia’s native Eastern oyster and the non-native Pacific oyster.

What happened next was a sort of fated coincidence.

In the 1990s, the Chesapeake Bay’s oystermen became interested in the Pacific oyster first, then the Asian Suminoe oyster, suspecting that either would be resistant to the oyster diseases in local waters. However, introducing non-native species could have unforeseen negative consequences for the Chesapeake Bay ecosystem.

To test whether the Suminoe oysters were disease resistant, they needed sterile oysters—just like the triploids Allen was already experienced at producing. For the experiment, ABC produced millions upon millions of oysters and handed them off to oyster growers.

“Well, not really ‘oyster growers’,” Allen says, “because at the time there wasn’t really a commercial aquaculture industry.” In fact, these impromptu growers were oystermen who were trying to make a living fishing for oysters.

These oystermen were trained to plant oysters, take measurements, and contribute their results to the larger scientific study. As a control group, triploid native oysters were grown alongside the Suminoe triploids. By the end of the trials, something unexpected happened—both species of oysters were still alive—the native triploids were disease resistant just like the non-natives.

“At that point, people realized that with the disease resistance of the triploid, they actually could grow the native oyster,” says Allen.

Oyster larvae 7-10 days old. ©ABC/VIMS

Oyster larvae at 7-10 days old are only 0.1mm long. ©ABC/VIMS

When the federal government declared in 2009 that non-native oysters should not be grown in Chesapeake Bay, growers had access to new equipment from the study and experience growing the just-as-good native oyster.

“Then the tires really started to catch traction on oyster aquaculture,” says Allen. But there was still a lot of trial and error. “Originally, we were just practicing caveman genetics and trying to get things started.”

And get things started they did. The oyster aquaculture industry was virtually non-existent before the experiments on Suminoe and native oysters started in 2005. Today, more than 65 million oyster seed are planted annually in Virginia, and about 90% of those are triploids from ABC’s broodstock. Of the remaining 10% of seed that are diploid, a good proportion of those also come from ABC’s diploid broodstock.

To continue supporting this growth, Virginia growers will need oysters that can outcompete other regions’ oysters in the national marketplace.

“We can no longer afford to do caveman genetics,” says Allen.

Now that the industry is on the move, ABC researchers want to know, can breeding help them get other beneficial traits?

This is Part 2 in the series: Selecting a Better Oyster about how Virginia Sea Grant-funded research will get more profitable oysters in the hands of growers.