To give birth to the Triploid oyster, no chemicals or genetic engineering are used. Our method is quite simply a tetraploid oyster which has basically 4n chromosomes and a diploid (the basic Pacific oyster) with 2n chromosomes and breeding them to get a triploid oyster. This is the only method used by Harstine Oyster Company. The tetraploid is a 4n chromosome oyster crossed with a diploid, 2n chromosome oyster to get a Triploid 3 chromosome oyster. At no time is any oyster altered in any way. A triploid oyster, when born, is a 3n Triploid Pacific oyster.
There is no spawning season for this type of Pacific oyster. The regular Pacific oyster (diploid) is spawning, hence giving us the old saying "Don't eat oysters in the months without "r"s. These are the spawning months for the Pacific oyster. The 3n Triploid Pacific oysters never go mushy or soft during the summer months when the diploid (regular Pacific oyster) can.
The acronym GMO stands for "genetically modified organism," and was first used years ago to designate microorganisms that had genes from other species transferred into their genetic material by the then-new techniques of "gene-splicing.' Applied to crops, the term refers to any genetic plant type that has had a gene or genes from a different species transferred into its genetic material using accepted techniques of genetic engineering and where such introduced genes have been shown to produce a gene product (a protein)." This definition is provided by Dr. Emerson D. Nafziger, Professor of Crop Production at the University of Illinois, (October 28, 1999)
Shellfish growers who are members of the Pacific Coast Shellfish Growers Association do not introduce genes from other species to their shellfish. PCSGA is not aware of this technology being utilized by any shellfish growers on the West Coast of the United States. Further, PCSGA will not endorse GMO technology for shellfish culture until such time that science clearly demonstrates that there is no human health risk associated with the practice.
For as long as plants and animals have been domesticated the tendency has been to select species for improvement like better growth, disease resistance, or any character allowing a better yield. With the advent of shellfish hatchery technology over the past thirty years, the West Coast shellfish industry has employed these more traditional techniques to improve their crops. There are three traditional methods used to improve the performance of shellfish species.
The first method is traditional selective breeding, where a heavy selection force is applied to the cultivated population, and the individuals presenting the better characteristics or phenotypes (like growth rate, shape, disease resistance....) are selected and bred again to create the next generation. This is the technique being applied currently to Pacific oysters by the Molluscan Broodstock Program housed at the Hatfield Marine Science Center in Newport, Oregon.
The second method is hybridization. This technique is based on the principle of "hybrid vigor" which has been highly demonstrated in the corn industry, where the cross of two highly inbred families will lead to a hybrid progeny presenting exceptional growth characteristics. The Western Regional Aquaculture Center is currently supporting research involving the hybridization of pacific oysters to improve performance.
The third and final method is polyploidy. Polyploidy is based on simply changing the number of chromosomes in one individual. These techniques are applied on the early embryo development and simply prevent the loss of chromosomes which would normally have been expulsed during meiosis. These polyploid individuals contain the same chromosomes that were present in the eggs. No foreign genes from other species are introduced in this process.
This approach has been widely used in the agriculture industry since for example, bananas are triploids (3n), wheat is hexaploid (6n), blueberries are naturally tetraploid (4n) and sugar beets are triploid (3n), issued aroma cross of tetraploid (4n) and diploid (2n) seeds.
Polylloidy allows the shellfish industry to produce animals that are sterile. This has many advantages in the culture of bivalves. Commercially cultivated species on the West Coast expend considerable energy on gametogenesis. In a sterile animal this energy is partially redirected to growth. Oysters typically become "soft" or spawny in the summer months making them less desirable for the raw bar trade. Sterile oysters stay firm and full of glycogen year round. In many growing areas oysters will spawn releasing up to 50% of their body mass and dramatically reduce crop yield for extended periods of time. This problem is averted with a sterile crop.