Life history traits of the sea snake Emydocephalus annulatus, based on a 17-yr study

Although sea snakes are important predators in coral reef ecosystems and have undergone substantial population declines in some areas, we have little robust information on life histories of these animals. Based on a 17-yr mark–recapture study of turtle-headed sea snakes (Emydocephalus annulatus) in New Caledonia (> 1200 individuals marked), we can confidently allocate ages to 539 individuals (1–11 yr of age). Using data for those snakes, we describe patterns of growth and reproduction. Using the entire data set, we also estimate annual rates of survival. One to three large offspring (300 mm snout–vent length [SVL]) are born after a prolonged (8-month) gestation. The young snakes grow rapidly until they are about 2 yr old (500 mm SVL), after which growth slows, especially in males. Most females begin reproducing at 3 yr of age, and they produce a litter (typically of two offspring) in about 2 out of every 3 or 4 yr thereafter. Annual survival rates are around 70%, but some individuals live for more than a decade. Overall, the life history of this species involves rapid growth and early maturation, followed by low but sustained reproductive output. Despite their relatively recent evolutionary origin, hydrophiine sea snakes are remarkably diverse in life histories as well as in morphologies and diets. Hence, even closely related taxa may differ substantially in their vulnerability to threatening processes.