World Aquaculture 49 eugenol, which makes handling them much easier for workers and less stressful for the fish. Survival rates of broodfish captured and handled with this protocol are greater than 95percent. Since 2002, southern flounder have spawned naturally every year after acclimation in broodstock tank systems. Broodstock Husbandry Flounder are held in raceway and round fiberglass recirculating tank systems, each equipped with a heat pump for temperature regulation, sand filter, and biological filter (Fig. 1). Tanks are covered or placed in a designated room with light control to allow photoperiod manipulation. Raceways are 15 m long, 0.75-1.2 m deep, and 2.4 m wide, with a volume of 38-45 m3. Round tanks are 3.6 m in diameter, 1.4 m deep, with a volume of 15 m3. With good water quality and monitoring for diseases and parasites, flounder can be maintained and spawned in these systems over several years following wild collection. Broodfish are fed to satiation once daily with a combination of frozen shrimp and cut sardines (Fig. 2). Recently captured flounder are fed a mixture of live and frozen shrimp during the first few weeks while fish learn to accept frozen shrimp. Mixing several older flounder with recently captured fish can promote more rapid acceptance of frozen food. It is important to train flounder to accept frozen foods quickly for continued gonadal development. In general, flounder do not feed aggressively so food is carefully and slowly broadcast in the center of the tank, allowing observation of the feeding response. If fish suddenly cease feeding or are observed to increase opercular beat rate, scratch their bodies against the tank walls or bottom, or cough, preventative measures are taken to minimize the impact of potential parasitic infestation. Amyloodinium infestations can be particularly devastating if left untreated. Copper sulfate is administered over several days when flounder show signs of this gill and skin parasite. Female flounder (1-2 kg) are typically larger than males (0.5 kg) and will usually consume the bulk of offered food, often biting or pushing smaller males away during feeding. As a consequence of this aggression, when flounder were held over from year to year with both sexes in the tank, many males were lost to malnutrition. This issue was resolved by separating male and female fish at the end of each spawning season and combining them approximately one month before spawning is anticipated, usually October or November. This protocol has resulted in larger, healthier males while greatly reducing mortality associated with competition for food. Male flounder typically produce small volumes of sperm, usually less than 0.5 mL, an important factor to consider for successful spawning of this species (Daniels et al. 2010). Separating flounder broodfish by sex has resulted in increased milt production and better overall health of males and has become an important part of broodstock management procedures at FAML in recent years. Fig. 1. Flounder broodstock in a raceway system. (Photo by Jeffery B. Kaiser). Fig. 2. Broodstock flounder in a raceway system feeding at the surface. (Photo by Jeffery B. Kaiser). Spawning After broodfish are collected, producing a large number of high-quality flounder eggs over several months is the overall goal. Having a reliable source of viable eggs over an extended period has facilitated research on culture of larval and juvenile flounder. After collection from the wild, 30-40 males and 10-15 females are placed in a broodstock tank and exposed to a specific photoperiod and water temperature regime. Initially these parameters simulate ambient conditions for the central Texas coast in November, which is 11 hours of daylight and approximate-
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