Triploid eastern oysters are an important component of the Maryland aquaculture industry because of their fast growth and sustained high meat yield. Commercially, triploids are produced by mating tetraploid oysters with normal diploid oysters. Developing tetraploid stock is crucial to meeting the growing demand for Maryland triploid oysters. However, it is challenging to produce and maintain excellent tetraploid lines for the benefit of industry. In short, there is a clear and pressing need for triploid and tetraploid lines that have region-specific beneficial characteristics, especially tolerance to low-salinity environments. In this project, we will establish the first generation of tetraploid stock derived from Maryland local oyster populations.