The Use of Reproductive Technology to Improve Flounder Growth

In the US, Paralichthyd flounder, summer (Paralichthys dentatus) and southern (P. lethostigma) flounder on the east coast and California halibut (P. californicus) on the west, are high-value finfish with established markets worldwide. While the demand for flounder remains high globally, fishing pressure has significantly reduced wild catches, such that demand often exceeds supply. Meeting the increased demand for flounder in U.S. and foreign markets will therefore require establishing and optimizing production through aquaculture. Paralichthyd flounder are widely cultured throughout the world, particularly in Asia, where production of Japanese flounder (Paralichthys olivaceus) exceeds 65,000 tons. Despite the high demand, and declining fisheries, flounder culture in the US is a nascent industry and we represent the only commercial producer of farm-raised summer flounder. With a decade of research, at various universities, on the reproduction, larviculture, and metamorphosis of summer flounder, we have sufficient technical information for commercial-scale juvenile production. In fact, we consistently produce 2-3 crops of up to 250,000 juveniles annually, and have done so for many years. To gain competitiveness on the global market, however, we must reduce the costs associated with juvenile growth to market size ("grow-out"). We believe this obstacle represents the last remaining hurdle for the expansion of the US flounder industry, and is the focus of this proposal. Key to viable flounder culture is the reliable production of faster growing, all-female stocks. Females grow 2-3 times faster and have larger maximum sizes than males. Our research demonstrated that the estimated breakeven costs for all-female populations of summer flounder are 35% less than that to grow mixed sex populations. By reducing the cost of production, both the US consumer and industry will benefit.