Grow-Out and Marketability Evaluation of Triploid DEBY Oysters

Triploid DEBY clearly outperformed their diploid counterparts in terms of survival, growth and condition over the course of this study at the site of Sweet Amalia Oyster Farm in Mathews, VA. By November 2004, when oysters were approximately 28 month old, cumulative mortality was 11 % in triploids and 43% in diploids. At that time, 41 % of the triploids were of market size (3 inch) whereas none of the diploids had even attained 2.5 inch. Condition of triploids and diploids similarly increased in fall 2003 and remained high over the winter and spring 2004. However, while condition decreased slightly in triploids a pronounced decrease was observed in diploids in summer 2004. Perkinsus marinus was nearly absent in August 2003 and its prevalence in triploids and diploids similarly increased to 90-97% in November 2004. In August 2003, prevalence of MSX was 4% in triploids and 40% in diploids whereas no MSX was present in November 2004. Based on the good performance of triploids oyster dealers started to purchase triploid stock at a wholesale price of $0.25 an oyster in fall 2004