As of 2015, the Kemp's ridley sea turtle is the most endangered with only around 1,000 nesting females left. Accurate population data does not exist for loggerheads, hawkbills, flatbacks, olive ridleys, green sea turtles and black sea turtles.
All seven marine turtle species are listed under the Endangered Species Act; however, scientists know olive ridleys are the most abundant sea turtles. Total sea turtle populations are generally unknown because males and juveniles do not come ashore to nest. Population data is based on nesting females, which is unreliable as some females do not nest every year while others may nest multiple times in a single season.