Captive reproduction of sea turtles: An important success story.
Proceedings of the International SymposiumReproduction of Marine Life, Birth of New Life! Investigating the Mysteries of Reproduction. February 21-22, 2009, Okinawa Churaumi Aquarium, 2009: 23-40.
All seven extant species of sea turtles are considered endangered or threatened with extinction. Because of their commercial value for food (particularly the green turtle) and for craft materials (bekko or tortoiseshell from the hawksbill turtle) they have been heavily exploited around the world. Sea turtles are also charismatic animals to view in large aquaria and three species have proven easily reared in captivity. Initially, in the 1970s, the green sea turtle was bred in captivity by the Cayman Turtle Farm on Grand Cayman Island in the Caribbean. Subsequently, the loggerhead, Kemp’s ridley and hawksbill have also been bred in captivity at several aquaria and research labs around the world. Research on captive sea turtles has proven very important in improving our understanding of the reproductive biology of sea turtles. Our group, as well as other researchers, has made key original observations on captive animals, particularly at the Cayman Turtle Farm over the last four decades. These include the first evidence of temperature dependent sex determination in sea turtles, the first understanding of the ovulation cycle in any sea turtle, the first description of the hormonal control of reproduction 2 in turtles, the first quantitative description of mating and courtship behaviour in a sea turtle, and the first captive breeding of the green, hawksbill, loggerhead and Kemp’s ridley sea turtles. In addition, multiple paternity has been observed in captive greens with as high as seven fathers in a single clutch. Proper nutrition in captive animals has permitted sea turtles to reach sexual maturity 2-5 times faster than they do in the wild. On the other hand, imbalanced free fatty acid ratios from the diet appear to cause a reduction in viability of captive bred embryos. Finally, unique observations of sea turtles in aquaria have improved our knowledge of physiological processes such as the occurrence and possible seasonal cycles of a softened plastron in adult males, an adaptation important in mating behaviour. It can be argued that successful captive breeding of four species of sea turtles, while not favoured as a current conservation strategy, has nonetheless reduced the prospect of extinction for these species. Captive breeding programs for the other three species would teach us much more about these turtles and improve the longterm conservation options for these species as well.