Sea Turtles & Humans - The Dilemma
Over 200 million years after the first turtle appeared on the earth (compared with half a million years for humans), and after surviving one or more great catastrophes that wiped out most life on the planet, sea turtles face a very precarious future. Several changes in the earth’s environment, most of which are related to rapid human population growth, threaten the sea turtle’s livelihood.
A series of extinctions has already begun that threatens to sweep away much of the planet’s diversity. Without a change in the human population trend, turtles and many other wild animals face a very bleak future.
Sea turtles’ ability (or inability) to adapt to environmental changes may play an important role in their survival (or extinction). Sea turtles show a surprising ability to alter their habits. When large-scale harvesting of sea turtles began in the Hawaiian Islands, for example, green sea turtles switched to feeding at night. Eventually, after years of protection under the Endangered Species Act, they once again swam into shallow areas to feed by day. They have now become so tolerant of humans that they will feed right among the legs of wading tourists.
That sea turtles have nested on newly created artificial beaches shows that even they can change a rigidly fixed behavior such as the choice of nesting beaches in some individuals. Recent experiments show that turtles are more capable of learning than had previously been believed. Turtles can adapt their behavior to take advantage of newly available food sources. However, such changes often take place over lengthy periods of time. A sea turtle cannot quickly analyze a situation and solve an immediate problem. Videos of sea turtles caught in the path of an approaching trawl net, for example, reveal that rather than ducking out of the net’s path, the turtle will continue to swim ahead until it is so exhausted that it falls back into the net.
Unfortunately, our world is changing so fast that sea turtles could never adapt quickly enough to save themselves. Human decisions alone will determine the fate of sea turtles. Most times, we have risen to this challenge and changed our own behavior to give sea turtles a chance to live. The harvest of sea turtles is prohibited in most countries, and technological innovations, such as TEDs (which allow turtles to escape from trawl nets) have decreased unintentional mortality. Protection of nesting beaches and imposed measures to reduce capture in fisheries have brought the Kemp’s Ridley Sea Turtle back from the brink of extinction.
But the recent threats sea turtles face will not be easy to counteract. Many biologists believe that the long-term survival of these animals is no longer threatened so much by direct harvesting as by large-scale environmental changes. In many areas, sea turtles are no longer hunted, but are still dying because of illnesses that could be related to pollution and global warming. Many turtles are killed by fishing gear that is not intended for turtles but has become so ubiquitous in their environment that they cannot avoid it. Although in many areas people are no longer harvesting turtles or their eggs from nesting beaches, turtle reproduction remains threatened because of property development, erosion, light pollution, and other changes that make the beaches no longer suitable for hatching baby turtles. We can address some of these problems with easy fixes, such as shielding beachfront lighting, but most are complex dilemmas without simple solutions.
Perhaps the most important step humans can take toward sea turtle preservation is to control our own population. But such a dramatic change will not come easily. Human attitudes toward reproduction are based in deeply rooted instincts and cultural and religious traditions that are highly resistant to change. It will be our own flexibility, rather than that of turtles, which seals their fate.