The Bermuda Turtle Project, the longest-running study in the world on juvenile green turtles and hawksbill turtles has reached a milestone. And for the first time, the global community will have access to the summary of the biology of these two species, shedding light on this significant stage of their life cycle in Bermuda a safe haven for some of the critically-endangered turtle species.

The Bermuda Turtle project (BTP) is an in-depth study of sea turtles that has existed for four decades. American couple Anne and Peter Meylan, an integral part of BTP since 1990, along with Jennifer Gray, who's currently with Bermuda National Trust, have finished a summary of the biology of green turtles and hawksbills in the Island's waters. In an exclusive interview with the Bermuda Environmental Alliance, Dr. Peter Meylan revealed some details of the extensive research on the two endangered turtle species, which has been turned into a scientific paper.

"The goal of this paper is to firmly establish that Bermuda serves as 'benthic developmental habitat' for immature green turtles and hawksbills during the juvenile developmental stage of their life cycle."

In other words, Bermuda is a year-round safe haven for immature green and hawksbills turtles, providing an important feeding ground for the Caribbean animals to grow and mature. It can be thought of as the 'boarding school' stage of the turtles' development, with their early years in the open ocean before reaching Bermuda equating to their 'nursery school' period, and when they leave Bermuda's waters after up to 14 years they mature 'at university' while on the long trip back to the Caribbean.

The newly completed scientific paper mainly focuses on the size of the turtles when they arrive in Bermuda, how long they stay, and their size when they depart. "An important part of the study was the use of laparoscopy to show that the green turtles in Bermuda are all immature."

Laparoscopy provides information on the reproductive organs to determine gender, maturity, and reproductive condition. It's a simple procedure in which a small incision is made through the body wall of the turtle and the gonads are viewed using a surgical scope. Through this procedure, the Bermuda Turtle Project scientists have examined 130 immature turtles. They were able to determine their sex from a direct look at the organs and at the same time establish a method that would allow the determination of sex from all turtles captured using a small blood sample.

"We know from many recaptures that laparoscopy does not harm the turtles. It was by looking at their reproductive organs that we were able to determine that all green turtles in Bermuda are immature and that they must go elsewhere before they mature."

Marine turtles travel hundreds, if not thousands, of miles across the oceans and cross borders probably using the earth's magnetic forces to navigate. They depend on land to lay their eggs on beaches and the ocean to grow and mature. Nesting takes anywhere from one to three hours for the mature female and, depending on species, lays 50 to 250 eggs in a clutch, one to ten times during each nesting season.

Sadly most of these eggs do not produce hatchlings that would survive to adulthood, for even before they hatch the eggs are harvested. As countries like Bermuda are trying to protect the species, in Caribbean nations like Costa Rica and Guatemala, human harvesting of their eggs continues to pose a serious threat to their survival. As you can see in these images from Costa Rica, even before the females deposit their eggs in their nests, people aggressively grab and stock them in huge sacks to be sold in markets for consumption. Costa Rica is a vital nesting habitat for the green and the hawksbill turtles and the fourth most critical nesting habitat in the world for the critically-endangered leatherback. The leatherback in the Pacific Ocean is so close to extinction that emptying just one nest of eggs will have huge implications for its survival as a species.

Mark Outerbridge, a young scientist for the Bermuda Zoological Society based at the Aquarium, and the BTP co-ordinator believes lack of proper education in the region is the main problem. He said: "Green turtles are considered globally endangered and regrettably the problem gets worse when eggs are poached based on blind beliefs such as the presence of aphrodisiac properties in them."

The Bermuda Turtle Project was created to shed light on some of these issues and educate the international community on the perils facing the green turtles. Since 1996, the BTP has hosted 135 students, mostly from the Caribbean and Central/South America.

"These students have left Bermuda with a firm understanding of the complex life cycle of sea turtles, the methods used to study them, and the steps needed to conserve them. Sea turtles of all species travel widely during their life cycle, which means sea turtles from Bermuda could go to almost any of the countries from which visiting students have come either before or after living in Bermuda. So, cooperation among nations is imperative for sea turtle conservation," said Dr. Meylan.

The story of green turtles in Bermuda goes as far back as the 1600s, when the Island was a fertile nesting ground for these adorable creatures. Shortly before colonisation, they thrived in the thousands in Bermuda's waters. As described on the Bermuda Turtle Project website, in 1610 settlers noted that "on the shores of Bermuda, Hogges, turtles, fish and fowle do abound as dust of the earth".

However with recorded takes of more than 40 turtles per boat per day, it was not long before the local stocks of sea turtles depleted. In 1620, only 11 years after Bermuda's colonisation, an act of the Bermuda Assembly against killing the sea turtles was passed. Unfortunately the law protected only young turtles, little did the settlers know at that time that it took up to 50 years for the turtles to reach maturity and reproduce and that the turtles living in Bermuda waters most likely nested in other countries. "They allowed catching all the big ones, which included mature females. These are the most valuable individuals and the only hope for the continuation of the species. This is why green sea turtles no longer lay eggs in Bermuda. If you exterminate the reproductive adults then you have a population problem," says Mr. Outerbridge

In an attempt to re-establish a nesting population in Bermuda, over 25,000 green turtle eggs were transplanted from Costa Rica in the 1960s and 70s by the Caribbean Conservation Corporation, now known as the Sea Turtle Conservancy, and buried on beaches in Bermuda. More than 16,000 of these eggs hatched. Knowing that turtles usually return to nest on the same beach that they were born provides hope that these animals will eventually nest in Bermuda.

"There might still be a chance that this will happen but it seems unlikely for several reasons. The survival of turtles from eggs to adult is very small. We don't know the exact numbers, but a number that is sometimes used as an estimate is one in 1000. So, if 25,000 eggs were brought to Bermuda this estimate would predict that 25 would reach adulthood," says Dr. Meylan.

The good news is that with each successful transition between life stages the turtles get closer to maturity and the chances of survival of the individual (under natural conditions) become greater. The first stage, one of the most precarious, is the "epipelagic" stage, as Dr. Meylan describes the "nursery school" stage in human terms. This is when the hatchlings leave the nesting beach and spend three to five years feeding on the open ocean. During this stage the turtles are closely associated with Sargassum, the brown algae that floats on the surface, which forms large mats for the marine creatures. According to Dr. Meylan "the Sargasso Sea is very likely to be an important place for hatchling green turtles to grow up to the size at which they move inshore and start feeding on the bottom instead of at the ocean's surface". Hatchling sea turtles have predators such as ants, crabs, lizards, birds and dogs, as well as carnivorous fish such as snappers, groupers, barracudas, dolphins and sharks.

If they survive this phase they will become juvenile turtles and spend their lives in benthic habitat that provides a shallow bottom to feed. This is the stage they travel to Bermuda. Green turtles feed mostly on sea grass and the hawksbill on sponges.

In sea grass ecosystems such as Bermuda, green turtles can be the most important herbivores, turning plant biomass into animal biomass, and in the process spreading "sea turtle manure" as well as providing nutrients to other forms of marine life.

The Bermuda Turtle Project's paper is currently being peer-reviewed and is expected to be published in a science journal sometime next year. Meantime you can log on to http://www.cccturtle.org/bermuda/discoveries.htm for general results of the Bermuda Turtle Project.

Dr. Meylan says this mission would've been impossible without the support of the Bermuda Aquarium Museum and Zoo, Bermuda Fisheries, Conservation Services, Bermuda Zoological Society, Caribbean Conservation Corporation (now known as Sea Turtle Conservancy), their many staff members and also the volunteers.

• The Bermuda Environmental Alliance website is www.bermuda-bea.org