Protecting the populations of green turtles requires an understanding of the impact of humans on turtles and of turtles on humans, writes Mark Hamann.
It took just over 100 years of European settlement on and around the Cayman Islands to drive what is reported as being the largest historical population of green turtles to extinction. While in some places and for some populations around the globe a combination of luck and careful management has helped to stem the decline, many populations continue to balance on the edge because of continued exploitation by man or because of too few attempts to deal with the decline in population in the past.
I became interested in sea turtles by accident. Through word of mouth, I heard about volunteer opportunities and spent a few summers as an undergraduate at Flinders University in Southern Australia tagging and collecting data on nesting sea turtles. After graduating in applied science, I was employed by Queensland Parks and Wildlife Service and travelled the length and breadth of the Great Barrier Reef working on a variety of sea turtle projects.
The subject of my PhD, begun in 1997, is an investigation of the potential relationship between the physiological processes and reproductive cycles of the green sea turtle. Working with the QPWS and colleagues from the university of Queensland, this has involved studying adult female turtles at various reproductive stages and locations. For my research we captured, hauled aboard, weighed and measured thousands of turtles - most weighing more than 100kg - and walked hundreds of kilometres around small barrier reef islands searching for and tagging individual turtles. Most important, however, we documented several physiological processes that act to regulate and maximise reproduction in these animals.
From the relative security of the Barrier Reef, I moved to Malaysia to run the field component of QPWS's Earthwatch project. Nearly a century of unrestrained egg harvesting there has pushed the leatherback turtle to the brink of extinction and has caused severe population decline in other species. For westerners, conservation is often a privilege because we can afford alternatives to exploiting endangered species. In Malaysia, literally thousands of clutches of sea turtle eggs pass through the markets every year to sustain local economies. We have made progress slowly, explaining the need to conserve the turtle population and working with local and federal fishery agencies. For example, locals have been employed to guard eggs and nests.
Our task has been to develop programmes to help monitor nests and improve their yield. Put simply, the aim is to help maximise the numbers of eggs and the quality of hatchlings reaching the sea.
My current position at Northern Territory University takes me into northern Australia. Here, indigenous and traditional land owners hold strong cultural ties to sea turtles, and many remote coastal communities still partly rely on sea turtles for food. I am working with them, trying to collect genetic and blood samples to assess the distribution, abundance and health of sea turtles in northern Australia, sharing "white fella" science with traditional ecological knowledge to develop regional strategies for managing sea turtle populations for the benefit of all people.
Mark Hamann is a research fellow at the Key Centre for Tropical Wildlife Management at Northern Territory University in Australia.