FAQ

What is Selective Breeding?

Selective breeding is the process of choosing parent oysters with desirable traits—such as fast growth, high survival, or good shell shape—and breeding them to increase the likelihood those traits are passed to the next generation. It's the same approach that has been used for centuries in agriculture, livestock, and even dog breeds,  but applied to oysters.  

In selective breeding, we choose oysters based on observable characteristics (their phenotype), such as shell size, meat yield, or survival. Because these traits are influenced by genetics (their genotype), we expect that, on average, their offspring will also perform better for those same traits. For example, breeding larger, faster-growing oysters together increases the likelihood that the next generation will also grow larger and faster than the population as a whole.

Selective breeding has been used for centuries to improve crops and livestock. Modern corn, tomatoes, apples, dairy cattle, chickens, and many dog breeds all exist because people have repeatedly selected individuals with desirable traits and bred them over many generations. Oyster breeding uses these same traditional principles to improve traits such as growth, survival, and shell quality.

What is a triploid/ what are polyploids?

Every oyster carries chromosomes, which contain its genetic information. Most oysters are diploid (2N), meaning they have two sets of chromosomes—one inherited from each parent.

Polyploid is a general term for organisms with more than two sets of chromosomes. In oysters, the most common polyploids are triploids (3N), which have three sets of chromosomes, and tetraploids (4N), which have four.

Triploid oysters are produced by crossing a diploid (2N) oyster with a tetraploid (4N) oyster. Because they have an odd number of chromosome sets, triploids are typically unable to reproduce normally. Instead of putting as much energy into spawning, they generally devote more energy to growth and maintaining meat quality throughout the summer months, which is why they are preferred commercially for consumption over diploids. 

Tetraploid oysters are not grown for food. At ABC, they are maintained as specialized breeding lines and are used only as parents to produce triploid offspring for commercial aquaculture.

Are polyploids GMO?

A GMO, or genetically modified organism, is by definition an organism that has had its genetic material changed through genetic engineering.  Genetic engineering involves modifying the gene sequences or transferring DNA from one organism to another.

Polyploids are NOT genetically modified organisms (GMOs). They do not contain genes from other species or have their DNA artificially altered. Polyploidy simply changes the number of chromosome sets an oyster has—a naturally occurring phenomenon that can also be produced using established breeding techniques.

Polyploidy is common throughout nature and in many foods we eat every day. Bananas are triploid, which is why they produce little or no seed. Many commercial watermelons are also triploid, giving us the familiar seedless varieties. Other crops, including wheat, potatoes, strawberries, and some blueberries, are naturally polyploid.

What's the difference between spat, seed, broodstock, larvae, etc?

How can I buy your oysters?

In short- you cant!  ABC produces our oysters specifically for distribution to commercial hatcheries who then use them to produce more oysters.  We distribute them as part of a royalty program that these hatcheries participate in.  They then keep them to grow out themselves if they have a nursery and farm, or else sell the eyed larvae/seed to commercial farms to grow out.  In many cases, oysters you find at a restaurant can come from our commercial partners, but they will always be a second generation, not direct from ABC.  If you are a commercial hatchery interested in utilizing our lines, please reach out to our Broodstock Manager, Nate Geyerhahn (nateg@vims.edu) to discuss our royalty program and learn more.   If you want to know how you can support our industry partners and purchase oysters from them, please visit the industry partners page

What is the difference between the different oysters you offer? 

ABC produces both diploid (2N) and tetraploid (4N) oysters for distribution.  Each line that we make is grown out in specific environments with variable disease and salinity pressures, which results in lines being selected for specific environments.  You can find even more detail about this on our broodstock offerings page

What is a terminal line vs a continuous line?

A terminal line is a “new” line  produced from the best-performing families each year in our breeding program. Rather than being maintained as a continuous breeding line from one generation to the next, each generation is created using parents selected from the top-performing families based on traits such as growth and meat yield.  This approach allows the line to continually incorporate the latest genetic improvements each year. A continuous line on the other hand is made from a very large selection of parents to increase genetic diversity, but is a closed system where all genetics come from within that line

Are all of your lines disease resistant?

Disease resistance is the ability of an oyster to reduce infection by a pathogen. Disease tolerance is the ability of an oyster to remain healthy and survive despite becoming infected. In practice, oysters selected for disease resistance often exhibit a combination of both traits, making them more likely to survive in areas where diseases such as Dermo or MSX are common.

Not all of our lines are selected for disease resistance.  For example, Lily and Lola are grown out and specifically selected to perform well in a low salinity site.  Dermo typically is not observed in lower salinity sites, thus these lines do not regularly experience disease pressure as much as moderate salinity sites do.   As such, they are not specifically selected for disease resistance and, as diploids, are not expected to handle disease exposure as well as other lines might.  They do however experience an environmental refuge when it comes to disease, when grown out in their selection environment

It's important to remember that no oyster line is completely immune to disease. When we describe a line as "disease resistant," we mean that the line has demonstrated better survival under disease pressure than unselected populations. Individual oysters within the line can still become infected or succumb to disease, and performance will vary depending on environmental conditions, disease intensity, and the genetics of each individual oyster.

What is an environmental refuge?

An environmental refuge is an area where natural conditions reduce or eliminate a particular stress, allowing organisms to thrive without needing specific adaptations. For eastern oysters, lower salinity waters serve as an environmental refuge from diseases such as Dermo and MSX because these pathogens do not survive or spread as well under low salinity conditions. As a result, oyster lines selected for these environments may perform very well without being genetically disease-resistant, provided they are grown out in that selected environment.