Sea Turtles as Metaphor

Marine turtles are at once emblematic flagships for the oceans, and umbrella species whose management must be directed at a series of linked ecosystems. People connect with sea turtles in different ways, viewing them a symbol of all enigmatic ocean creatures, or as the face of an ageless cautionary tale about man versus nature.

The strange attraction that people feel towards sea turtles makes them symbols of something bigger -- clear candidates for flagship status. Their story is indeed the story of all the ocean’s inhabitants, though saving them from extirpation involves special a suite of conservation tools and policies. Sea turtles have been around a long time, some sixty million years, and for this reason they hold our fascination as ancients. They are charismatic megavertebrates, ever so graceful as adults swimming through the water and oh-so-cute crawling out of the nest. And they share some traits with us – needing to breathe at the surface, returning to land to reproduce, struggling to survive and keep their evolutionary lineages going in a rapidly changing world. Perhaps it is these traits that make it so sea turtles in harm’s way conjure up such pathos – whether it is the sight of the turtle drowned in the fishing net, of feral dogs attacking a stalwart nesting female, of tiny hatchlings undertaking the mad scramble down the beach.

Marine turtles are arguably the most logical organisms to denote as umbrella species. Their conservation requires the preservation of intact habitats ranging from tropical nesting beaches to sub-Arctic foraging grounds. Although this is also true for highly migratory species of fish and for most marine mammals, sea turtles are unique in that they rely not only on ocean habitat but also on terrestrial habitat. Nesting beaches must remain open and secure for sea turtles to utilize them, access to these beaches must be maintained, and the nesting beach environment must be almost pristine to successfully support sea turtle reproduction. The more disturbance on the beach, the greater the chance that the female will abort her eggs in the water or unsuccessfully attempt to make her nest, known in the turtle lingo as a “false crawl”. Light contamination on the nesting beach – a common occurrence on most beautiful wide sandy beaches in the tropics where sea turtles lay their eggs – dooms both adults and young, as light from behind the beach fatally draws turtles away from the sea.

Once the hatchlings leave the safety of their underground nest on the sandy beach, they scurry to the ocean to escape the innumerable dangers of land and find relatively safe nursery habitats in which to grow. Just where these nursery grounds are is still a mystery – in the Atlantic Ocean the Sargasso Sea has been fingered as the most probable place where small turtles can both find food and escape predation by hiding in the drifting sargassum weed. As sub-adults, sea turtles often congregate in nutrient rich shallow waters, to continue their slow growth to adulthood (most species take a decade or more to mature and will live for several.) These critical areas vary according to the species – for herbivorous green turtles, seagrass meadows and areas of algal-encrusted rock reef are preferred; for the sponge-eating hawksbills, diverse and healthy coral reefs are the only habitat where they can survive; for leatherbacks, cold and rich upwelling areas in temperate zones provide large quantities of the jellyfish they consume with vigor, and for the others that are omnivores, areas that support large populations of benthic fish and crustaceans are the coastal habitats of choice.

Adult turtles may go to different feeding grounds altogether, and when sexually mature will travel to breeding areas to mate. Gravid females come ashore on tropical nesting beaches to lay their eggs – a hundred or more at a time, in nest pits that they painstakingly excavate with their hind flippers. The process of finding access to the beach, hauling a huge body built for aquatic life onto gravity-encumbered land, then crawling with flippers made for water across wide swaths of sand, rock, and berms, is extraordinarily difficult. Finding a suitable nesting spot (like all reptiles, turtles do not incubate their eggs but rather let the warm sand of tropical beaches do it for them – the temperature and moisture level must be just so…), digging the nest, laying the eggs, then carefully covering the nest and disguising it takes hours, by which time the mother turtle is spent – and highly vulnerable to a host of predators that include man.

So, the need to meet the ecological requirements of these far-ranging species is huge. Yet in addition to protecting these disparate critical habitats on land and in the sea, conservation of sea turtles requires maintaining connections between these places. Migration corridors link tropical nesting beaches with temperate feeding grounds, sometimes thousands of miles away.

Sea turtles are considered other sorts of symbols as well, beyond flagships or umbrella species. Some view sea turtles as canaries in the coalmine, reminding us of how our impacts on the oceans are reaching critical thresholds. A good example is provided by the hawksbill, which frequents coral reefs in all the world’s tropical seas. The hawksbill turtle could be considered a keystone species of sorts: its grazing on a wide assortment of sponge species on the reef prevents any one sponge from dominating the reef and thereby reducing biodiversity and productivity. When hawksbills disappear from large reef tracts, they may well signal the decline of these delicately balanced ecosystems.

To other people, sea turtles are a highly valuable commodity. Sea turtle meat is considered an important food source; sea turtle eggs, though widely protected, are coveted not only as food but as aphrodisiacs in some places. The beautiful shell of the hawksbill, known as beko in the trade, is still being used to make expensive bracelets, combs, eyeglass frames, and other curios. Sea turtle bones, fat, and oil are used for medicinal purposes (though their curative value has never been scientifically demonstrated). Then there are the non-market values attached to these marine icons. Sea turtles are revered in some religions. Tourists speak of life-changing experiences when interacting with them.

For all the ways that we value sea turtles, one hopes that the most appropriate analogy is not that of the passenger pigeon, a species whose great value spelled its ultimate doom.