Transforming Lives in Coastal Communities Through Economic Development: Breeding Crassostrea virginica for Alternative Oyster Culture

Abstract

This dissertation helped address the commercialization of triploid Crassostrea virginica production and develop tetraploid C. virginica broodstock in Louisiana by addressing triploid commercialization and tetraploid broodstock development. This was done by: 1) developing regional breeding plans for diploid and tetraploid C. virginica targeted at the Gulf Coastal Region, 2) assessing the effect of chromosome set manipulation on gonadal development in diploid, triploid, and tetraploid C. virginica, 3) quantifying the variation of commercially important hatchery traits in triploid C. virginica larvae from different tetraploid parents, 4) developing an up-to-date remote setting manual for the Gulf Coastal Region for industry use, and 5) performing a basic economic analysis to produce an enterprise budget for floating cage oyster farming in the Gulf Coastal Region. I designed two breeding programs for oysters in the Gulf of Mexico Region: a diploid oyster breeding program and a tetraploid oyster breeding program. These breeding programs were designed to exploit genotype-by-environment interactions and combining abilities. To improve breeding, an analysis of gonadal development revealed 76% triploids exhibited abnormal and retarded gonadal development, whereas tetraploids followed diploid gonadal development with the only exception being a temporal delay. Investigating differences in larval traits attributable to the tetraploid parent suggested potential routes of selective breeding to add value to triploid offspring and make the hatchery production of triploid oyster larvae more efficient. These traits were hatching rate, survival, time to pediveliger development, and duration of pediveliger harvest. Improvements in these traits would increase hatchery production capacity and efficiency. The final chapters provide two tools aimed at lowering entry or expansion barriers for oyster aquaculture activities: a remote setting manual and enterprise budget for off-bottom oyster farms. The aim of these chapters was to deliver tools for industry that are current, applicable, and useful. Both manual and budget worksheet will be available through Louisiana Sea Grant College Program.