Sea Turtle Survival Ratesby | 13-07-2015 00:46 |
---|
![]() Today, I would like to introduce you the survival rate of sea turtles from hatchling to adulthood – corresponding to the numerous obstacles they face. I collected data from beaches to estimate the survival rate of sea turtles all across the world. I concluded that less turtles survive with the passage of years. While collecting information from beaches far away, I used useful sources such as 'Sea Turtles - an ecological guide' and videos from TED. To begin with, mother sea turtles dig a nesting pit high on the beach, depositing a lump of small, white eggs. Scientists have confirmed that nesting activity has plumeted by 28% since 1989. Even worse, about 20% of the 50 to 200 eggs will never hatch. Roughly a 30~60 days after having been laid, young turtles rise to the surface. Along the way to the surf, raccoons, debris, seabirds, crabs, pitfalls, and other threats will kill those that hatched. The hatchlings who actually reach the surf trade 1 set of threats for another. As they first face the tumultuous waves, they find a whole new host of predators awaiting them – fish, dolphins, and seabirds. In this stage, approximately 50% of those who reach the surf die. With the passage of years, the surviving turtles will increase in size (from that of a dinner plate at year 1 to that of a dinner table) within 10 years. A study conducted on this topic shows that body size positively corresponds to speed, so larger turtles are exposed to predators for a shorter amount of time. The only predators now are some species of shark and the killer whale. In two decades, the survivors will be old enough themselves to mate. Within the several last decades, human endeavors from beach development, plastic trash, poaching, artificial lighting, nets, and noxious chemicals has caused the survival rate to drop to around 1% or less. This added human pressure has pushed all 7 sea turtle species - the green sea turtle, the loggerhead sea turtle, the leatherback sea turtle, the hawksbill sea turtle, the kemps ridley sea turtle, the olive ridley sea turtle, and the flatback sea turtle...either into ?threatened? or ?endangered? state. Advances in micro-technology have allowed researchers to use transmitters and satellites to collect data on sea turtles over time. Using these sources, scientists collected information regarding location, depth and water temperature to calculate sea turtle survival rates. The data helped scientists track down the life of sea turtles migrating, navigating, and foraging. Other contrasting data suggest that 1 out of 30 turtles survive to adulthood. However, in this research, only 30 turtles were sampled and 29 died – it takes a great number of samples and time to estimate sea turtle survival rates. According to other studies, 80% of East Pacific green turtle deaths in California were associated with human activity. So let?s quickly look back at the cycle of odds, using a hypothetical nesting season. If there are 1000 thousand eggs laid, 800 hatch. 400 make it to the water, and 200 grow up as juveniles. 20 survive to breeding age without human interference. With human interference, 1 survive to maturity. Many indigenous people, however, still hunt sea turtles or gather their eggs for food, despite the strict prohibition of international law. Moreover, plastic, Styrofoam, packaging materials, aluminum foils, and everyday trash that we discard – are fatal to sea turtle survival. By working to conserve sea turtle habitats, I hope we will someday turn the 1 out of a 1000 into 1 out of a 100. |