NUTRITIONAL PHYSIOLOGY OF MAHI-MAHI Coryphaena hippurus AND THE IMPACTS OF FEEDING ON SWIM PERFORMANCE

The mahi-mahi (Coryphaena hippurus) is a species of high economic and ecological value found throughout the world's tropical and subtropical oceans. Demand for this species as table fare has continued to rise over the past decade, while wild-catch levels fluctuate on seasonal and annual bases. Such conditions have attracted increased attention on development of commercially-viable aquaculture techniques and technology for mahi-mahi. As a fast-growing highly fecund migratory pelagic species, mahi-mahi must balance multiple metabolic demands concurrently to survive in the wild. Research has shown that this species consumes substantial quantities of food during the juvenile and adult stages of growout in captivity, in some cases over 20% bodyweight in single feeding events. However, to date there is no data on the nutritional physiology of adult specimens of this species.  Such information is essential to not only understanding the overall physiology of the species but also to optimizing the culture of this species in captivity. Whole fish and squid are commonly used for feeding mahi-mahi broodstock in captivity, while manufactured pelletized diets have also demonstrated effectiveness in pilot-scale commercial trials of juveniles and adults. Given the substantial contribution of feed costs to overall operating expenses in fed aquaculture enterprises, it is critical to understand the nutritional physiology of species being cultured.  Whole-animal physiological studies examining the metabolic costs associated with digestion, typically referred to as postprandial metabolism or specific dynamic action (SDA), provide high-resolution data on diet-specific metabolic responses that can be used for improving feeding efficiencies and diet formulations. Results from studies examining the postprandial metabolic response of feeding both natural diets (i.e. forage fish/squid) and manufactured pelletized diets will be presented, along with results investigating the impacts of feeding on swim performance in this species. This research was made possible by a grant from The Gulf of Mexico Research Initiative.