THE STATUS OF SOUTHERN FLOUNDER Paralichthys lethostigma AND SUMMER FLOUNDER Paralichthys dentatus AS EXPERIMENTAL SPECIES FOR U.S. MARINE AQUACULTURE

Interest in commercial foodfish production of both southern flounder (Paralichthys lethostigma) and summer flounder (P. dentatus) began in the mid 1990's at several universities, marine fisheries agencies, and research institutes on the East coast of the US.  Initial research efforts focused on developing methods for controlled reproduction of broodstock and for mass production of fingerlings.  Later work on commercial technology for growout mainly involved the design and use of recirculating aquaculture systems (RAS) for land-based production in tanks.  Foodfish production of summer flounder first met with some commercial success as several private companies began marketing their cultured fish to the live fish markets.  However, importation of live flounder from Asia led to a depression of prices to the level where it was no longer economically feasible for US producers. More recently, state marine fisheries agencies, notably Texas and Alabama, are launching stock enhancement programs for southern flounder to support the recreational harvest of this popular fish.  Some biological constraints common to both these flatfish pose unique challenges for producers of flounder for either foodfish or stock enhancement.  Chief among these challenges is the strong degree of sexual dimorphism that occurs with the southern flounder and to a lesser degree with the summer flounder.  Male flounder are much smaller than the females and rarely reach market size, effectively lowering the proportion of fish that are sold at the highest price.  Additionally, the tendency toward male-skewed populations further contributes to the negative effect of dimorphism on production economics.  The causes of sexual dimorphism are fairly well known, but are difficult to control.    Economically viable foodfish production of both southern and summer flounder will be greatly improved when methods to control sexual dimorphism are developed.