Sea Turtle Nutrition in the Rehabilitation Setting: Are They Really What They Eat?
Given that a large proportion of the sea turtles entering rehabilitation facilities are in a state of nutritional deprivation, even emaciation, a relatively efficient and controlled return to normal body mass is imperative to the successful return of these animals to the wild. Little has been documented on the feeding habits and nutritional requirements of these species even in their natural environment, and even less so on appropriate and effective standards for nutrition during rehabilitation.
An informal survey of facilities engaged in the rehabilitation of sea turtles, primarily located along the Eastern and Gulf Coasts of the United States, established that the majority of facilities offer a variety of foodstuffs to each patient. The most common diet offered is comprised of some form of shellfish and/or bony fish, in addition to squid, as this is often the most widely accepted option by the animals entering rehabilitation. The most common techniques used by these facilities for formulating dietary plans involve a simple percentage of body weight formula, adjusted as necessary for the individual animal. For a number of reptile species commonly maintained in captivity, several formulae have been established for calculating metabolic and nutritional requirements, but the effectiveness of these has not been determined for marine reptiles.
Detailed feeding and weight records for a population of subadult and adult sea turtles at one rehabilitation facility on the West coast of Florida were examined for correlations between the quantity and type of food consumed and the level of weight gain throughout rehabilitation. For most of the individual records examined, the quantity and rate of weight gain in a rehabilitation setting appears to be a direct result of the mass of foodstuffs consumed. The strength of this association decreases with an increase in the proportion of squid included in the diet, which may be expected given the relatively lower nutrient density of squid. In a population of juvenile (<10kg) turtles undergoing rehabilitation at the same facility, weight gain correlates more strongly with initial body weight than with percentage of body mass fed, with smaller animals gaining weight more rapidly even when fed at an equal ratio to larger animals.
This suggests that for animals of a reasonably mature size, assuming all essential nutrient requirements are met, the rate of weight gain and return of body mass may be rather simply controlled through adjusting the quantity offered of such high quality foodstuffs as shellfish and bony fish.
The first author would like to gratefully acknowledge the assistance and advice of Drs. E. Scott Weber, Gregory Lewbart, and Craig Harms. In addition, many thanks to all individuals and facilities who contributed to the survey.