Triploid oysters, the predominant choice in commercial off-bottom oyster farming, are relatively reproductively sterile and often exhibit faster growth and higher meat yield compared to diploid oysters, especially during spawning season. The mating of tetraploid male broodstock with diploid female broodstock results in the production of 100% triploid oysters. Understanding how different environmental variables may influence the survival and growth of tetraploids is crucial in producing a more resilient triploid oyster.
Two tetraploid broodstock lines maintained at the Auburn University Shellfish Laboratory (AUSL), 4MGNL20 (Louisiana origin) and 4MAPCK20 (Florida origin), were spawned to produce four experimental cohorts: two pure lines (4MGNL22 and 4M3APCK22) and two reciprocal crosses between the two lines (4MAPCKGNL22, and 4MGNLAPCK22). The tetraploid lines were produced in conjunction with 4Cs Breeding Technologies, Inc with the GNL tetraploid line originally produced at the Louisiana Sea Grant Program’s Oyster Research Laboratory at Grand Isle, LA and the APCK tetraploid line originally produced at AUSL. Four replicates (400 oysters/replicate) of each experimental cohort were deployed in Oyster-Gro floating cages at three differing salinity sites in Alabama: Mobile Bay (low salinity), Grand Bay (moderate to high salinity), and Dauphin Island (high salinity). Mortality and size metrics were assessed monthly. Temperature and salinity measurements were taken at all three experimental sites.
Preliminary data suggest a significant effect of site and tetraploid line on survival and shell height (p < 0.01). At the low salinity site, 4MGNL experienced a higher mortality (p < 0.05) (Figure 1).
This is an ongoing experiment and data will continue to be collected over 12 months. Trends will be reassessed to determine the next steps in selecting a more resilient tetraploid broodstock for triploid production in the northern Gulf of Mexico.