To achieve triploidy, tetraploid males are identified from our select brood stock lines before spawning. Males are sacrificed and their sperm is used to fertilize eggs from the customer's normal, diploid brood stocks. No induction is used, and the fertilized eggs—now 100% 4Cs natural triploid—can be immediately incubated for culture. For more information on the process of producing natural triploids, see Development of Natural Triploidy.
Under controlled tests, the hatching rate of 4Cs' natural triploids was equal to normal diploid spawns (see table below, also view more studies). Additionally, 4Cs' natural triploids have a considerably higher hatching rate than that of induced triploids.
D-hinge larvae (two days old) of both natural and induced triploids are larger than diploids. The average daily growth of natural triploid larvae is nearly 50% faster than induced triploids and diploids, culminating in large eyed larvae. Specifically, 4Cs' natural triploid eyed larvae of C. gigas are almost 350 microns compared to about 320 for diploids and induced triploids. In volume, 4Cs' natural triploid larvae are approximately ⅓ larger.
In our SBIR research project with a West Coast US hatchery, we found that 162 of 170 commercial spawns of 4Cs' natural triploids were greater than 95% triploids and that 153 were 100% triploid. In comparison, 80% is generally deemed acceptable for induced triploid spawns. To date, 100% triploids have been produced from tetraploids in three species of oysters: C. gigas, C. ariakensis, and C. virginica.
What can you expect in the hatchery?
|Diploid||Induced Triploid||4Cs' Natural
|Hatching rate (%)||48.3||16.8||48.0|
|Size at 48 hours (micron)||82.0||86.4||86.3|
|Size at day 12 (micron)||158.2||168.1||198.6|
|Average daily growth (micron/day)||7.6||8.2||11.2|
|Survival to day 12 (%)||32.8||34.4||35.3|
|Size at eyed stage (micron)||319.5||320.2||346.6|