The age of sexual maturity is difficult to estimate for a species such as the loggerhead sea turtle (Caretta caretta) due to scientists’ lack of accessibility of sea turtles throughout their life cycles. This information however, is of the utmost importance if researchers are to assess the conservation status of this potential endangered species (Lewontin 1965; Berner & Blanckenhorn 2007).
Loggerhead turtles have been documented to reach sexual maturity at a range of ages, estimates of the mean age at maturity for loggerhead sea turtles (Caretta caretta) in the western North Atlantic range from 6·5 years (Caldwell 1962) to 39 years (NMFS-SEFSC 2001). This wide range of data has proven to be problematic for loggerhead researchers and offers no concrete evidence supporting any ages represented in the data range. Problems with inconsistent data ranges can lead to cascading effects. For example, for northern right whales, Eubalaena glacialis, in the Atlantic, the late age at maturity contributes to low reproductive output, and hence, the premature death of even a few mature females (e.g. through ship collisions) may drive the population dangerously low. Without an accurate estimate of when loggerhead sea turtles reach sexual maturity, their fate could be shared with the northern right whales.
The goal of this research was to compare loggerhead turtles sexual maturity age to other marine organisms of similar size and weight. Size data was collected from a total of 273 loggerhead turtles encountered around the coast of the UK/France, 2318 individuals from the Azores and 52 from the Pacific.
This data was compiled and analyzed and the study supported that loggerhead sea turtles in general are older at maturity than species of equal mass. The average age of maturity was estimated at roughly 45 years old. Although this data is not conclusive, it does support the need for stricter conservation laws that will allow more sea turtles to reach sexual maturity and increase the worldwide population of loggerhead sea turtles.
Berner, D. & Blanckenhorn, W. (2007) An ontogenetic perspective on the relationship between age and size at maturity. Functional Ecology, 21, 505–512.
Caldwell, D. (1962) Growth measurements in young captive Atlantic sea turtles in temperate waters. Los Angeles City Museum Contribution to Science, 50, 1–8.
Lewontin, R.C. (1965) Selection for Colonizing Ability. The Genetics of Colonizing Species. Academic Press, New York, USA.
NMFS-SEFSC (2001) Stock assessments of loggerhead and leatherback sea turtles and an assessment of the impact of the pelagic longline fishery on the loggerhead and leatherback sea turtles of the Western North Atlantic. US Department of Commerce NOAA Technical Memorandum NMFS-SEFSC, 455, 343.
Article source: http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2435.2011.01915.x/pdf