Effect of diet on growth in captive Podocnemis unifilis: assessing optimal diets for turtles in head-starting programs

Abstract

Because turtles have come under increasing pressures from habitat loss and over-exploitation as food sources and traditional medicine, efforts have focused on options for conservation, including head-starting programs. Success of head-starting programs depends on establishing economical means of rearing hatchlings over relatively short time frames to sizes resistant to predation. We examined effects of three different diets on growth of a clutch of captive Yellow-spotted Amazon River Turtles (Podocnemis unifilis) over a two-year period in a Florida zoo. Rates of growth differed among the three treatment groups; relationships between morphological variables were not affected by diet. Results indicate that turtles fed on a commercial gel diet may exceed growth rates of animals fed on a more natural, vegetarian diet by more than 15% as measured by straight-line carapace length, or by more than 50% in body mass. Use of a vegetarian diet reduced costs to less than 10% of the cost of a commercial gel diet. Choice of diets for turtles in head-starting programs is a variable that should be weighed against other conservation objectives such as captive duration and intended sizes attained.