On the east coast of the United States, the overexploitation of flatfishes has been increasingly apparent in recent years. With the decline in U.S. landings of flatfish species in the Atlantic states, more stringent management regimes have been created to rebuild these stocks. These flatfish fisheries have historically been of high economic importance to working waterfront communities. With reduced quotas and other management restrictions for flatfish species in these states, working waterfront communities have been heavily impacted. Reducing harvest quotas can stunt economic prosperity, as well as force fishers to find other sources of income. While such situations are not unique to fishing communities throughout the U.S., there is the potential for sustainable flounder aquaculture to be implemented in regions historically reliant upon wild flatfish landings. These working waterfronts stand to benefit from supplementing wild caught flatfish demand with a farm-raised alternative in an already established market.
The olive flounder, Paralichthys olivaceus, is a commonly cultured species in both Japan and Korea and is often referred to as hirame. This species has a low FCR, high growth rates for flatfish species, and can be grown at high stocking densities compared to other commonly cultured marine finfish species. At the University of Miami Experimental Hatchery (UMEH), broodstock olive flounder volitionally spawn regularly and produce high quality fertilized eggs. Recent efforts with this species have been focused on developing grow-out production economic models for this species in pilot-scale land-based seawater rearing systems while also significantly increasing seedstock supply through nursery production trials to service prospective farmers in the U.S. At the UMEH facility, seedstock production begins following a broodstock spawning with the collection and stocking of fertilized embryos into larval rearing tanks. The larval olive flounder are reared on rotifers, Artemia, and micro diets before being transferred to raceway tank nursery systems by day 45 post hatch. Juvenile fish in these raceways are typically stocked at densities of 2.1 - 4.4 kg/m3 (0.6 - 1.1 kg/m2), and final densities in these raceways range from 96 - 247 kg/m3 (25 - 47 kg/m2). During their time in these nursery systems, juvenile flounder are transitioned onto progressively larger dry feeds, with high survival and low FCRs over the course of this period. Results of recent seedstock production and nursery trials will be presented, as well as other aspects of this flounder project supported by the Atlantic States Marine Fisheries Commission (ASMFC) and the National Oceanic and Atmospheric Administration (NOAA). The consistent production of flounder at high densities in land-based aquaculture systems supports the fact that olive flounder is a prime species candidate for land-based aquaculture in the U.S. and offers an exciting opportunity for diversification in working waterfront communities of the U.S.