The Survival of the Sea Turtle


Sea turtles are miraculous. First, they’ve been around
since the late Jurassic, roughly 150 million years ago. Cohorts of the dinosaurs, sea turtles have survived
through the challenges of eons, existing still today, where many others
have ended their evolutionary run. Second, throughout the centuries
and up till today, every living adult sea turtle
has overcome the odds, existing as a consequence of chance, skill, and capability. The gauntlet each sea turtle faces
in the course of its lifetime goes thus: First, deposited as a clutch of leathery,
ping-pong ball-sized eggs into a nesting pit dug by its mother
high on the beach, of the 50 to 200 eggs laid, roughly 20 percent will never hatch. Roughly a month and a half
after having been laid, the surviving eggs hatch, and the young turtles, each small enough
to fit in the palm of your hand, squirm to the surface,
emerging from the sand en masse, and making their desperate
dash for the sea. Along the way, debris, pitfalls, crabs, gulls, raccoons, and other threats will claim roughly 50 percent of those
who rose from the sand. For those that actually reach the surf, they trade one set of threats for another, as they first face
the repelling force of the waves, and then find a whole new
host of predators awaiting them: Various fish, dolphins,
sharks, and sea birds, as the young turtles
come to the surface for air. For their first few days of life, should they count themselves
amongst the living, the vulnerable turtles
swim frantically forward. Ultimately, they will often
look to settle in a patch of flotsam, preferably a patch of floating seaweed. Now for the next several months, they will seek to avoid
those that would eat them, find that which they might eat themselves, and not fall to the pressures
of challenging weather or unfortunate currents. In this phase, roughly 50 percent
of those who reach the surf will perish. Ultimately, with the passage of years, the survivors will increase in size, from that of a dinner plate at year one to that of a dinner table, in the case of one species
at least, the leatherback, a decade or so later. With size comes
some measure of protection. The only truly worrisome predators
now are some of the larger shark species– bulls, tigers, and whites — and the occasional killer whale. At approximately two decades of age, the survivors will be old enough
themselves to breed, and continue the cycle
which their very existence heralds. Of those that began
as eggs on a distant beach, now less than 10 percent remain, at least, those were the odds
prior to significant human interference. Over the past century, and in particular
in the last several decades, human endeavors, from beach development to plastic refuse to poaching,
long lines, nets, and even noxious chemicals, including oil, have upped the ante for sea turtles, causing their survival rate to drop
to around one percent or less, from each nesting cycle. It is this added human pressure
which has pushed each of the eight sea turtle species into either a threatened
or endangered state. For while they have evolved
to overcome a host of obstacles, the most recent has arisen so quickly and at such scale that the species
find themselves overwhelmed. So let’s quickly recap this cycle of odds. Using a hypothetical nesting season, for females may nest
multiple times in a single year, of 1,000 eggs, for sake of ease. 1000 eggs laid. 800 hatch. 400 make it to the water. 200 progress toward adulthood. 20 survive to breeding age — that is, without human interference. Two survive to breeding age
with human interference. So a breeding adult sea turtle
is the very embodiment of a long shot. It is the exception, not the rule. A jackpot. It is, in a very real sense, a miracle.