WASHINGTON (CN) – The U.S Fish and Wildlife Service has determined that the world wide population of loggerhead turtles can be divided into nine distinct population segments. The agency plans to list seven of them as endangered and the remaining two as threatened, according to an agency proposal.
First listed as threatened across its range in 1978, the loggerhead occurs throughout the temperate and tropical regions of the Atlantic, Pacific, and Indian Oceans with the majority of loggerhead nesting occurring at the western rims of the Atlantic and Indian Oceans. Each population has distinct DNA strains that remain distinct because the range of each population is limited and defined by ocean currents or gyres that allow only a few individuals to leave their own population and mate into another.
The agency proposes to recognize the following discrete population segments: The North Pacific; the South Pacific; the North Indian Ocean; the Southeast Indo-Pacific Ocean; the Southwest Indian Ocean; the Northwest Atlantic Ocean; the Northeast Atlantic Ocean; the South Atlantic Ocean, and the Mediterranean Sea Distinct Population Segment.
The agency has found that the Southwest Indian Ocean and the South Atlantic Ocean segments face sufficient risk of extinction in the foreseeable future to warrant a threatened listing under the Endangered Species Act, while the remaining populations warrant an endangered listing under the act.
Fishing, both net and long-line, is the number one threat to loggerheads, despite provisions in most world fishing conventions to protect the species.
Loggerhead hatchlings have a 40 percent survival rate overall but individual populations have suffered drastic declines in hatchling viability due to habitat destruction and deliberate hunting of nesting females.
Climate change has a significant impact on the loggerhead’s reproductive success as the temperature of the sand around their nest determines the sex of the hatchlings, with higher temperatures favoring females and lower temperatures favoring males.
Because females have up to a 25 year span for reproduction, and can live to be over 50 years old, long term trends in the population can be predicted based on the survival rates and sexual population biases measured in a single female’s successive broods.
The agency will accept comments on the proposed listing until June 14 and comments calling for public hearings until June 1.