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.

海龟是神奇的。

首先,它们
从侏罗纪晚期就存在了,

大约 1.5 亿年前。

恐龙群,

海龟在历经千百年
的挑战中幸存下来,

今天仍然存在

,许多其他人
已经结束了它们的进化过程。

其次,几个
世纪以来直到今天,

每只活着的成年海龟
都克服了困难,

因为机会、

技能和能力而存在。

每只海龟
在其一生中所面临的挑战是这样的:

首先,将一堆乒乓球大小的皮革卵

放入其母亲在海滩高处挖的一个筑巢坑中

其中有 50 到 200 个卵 铺设,

大约 20% 将永远不会孵化。

产下大约一个半月后

,幸存的卵孵化

,小海龟,每只小
到可以放在你的手掌中,

蠕动到水面,成群结队地
从沙子中冒出来

,拼命
冲刺 为海。

一路上,碎片、陷阱、螃蟹、

海鸥、浣熊和其他威胁

将夺走大约 50% 的
从沙滩上爬起来的人。

对于那些真正到达海浪的人来说,

他们会用一套威胁换取另一套威胁,

因为他们首先要面对
海浪的排斥力,

然后会发现一大群新
的捕食者在等着他们:

各种鱼类、海豚、
鲨鱼和海鸟 ,

当年轻的
海龟浮出水面呼吸时。

在他们生命的最初几天,

如果他们把自己
算在生命中

,脆弱的海龟会
疯狂地向前游泳。

最终,它们通常会
寻求在一片漂浮物中安顿下来,

最好是一片漂浮的海藻。

现在在接下来的几个月里,

他们将设法避开
那些会吃它们的人,

找到他们自己可能吃的东西,

而不是屈服于
恶劣天气

或不幸海流的压力。

在这个阶段,大约 50%
的冲浪者

将会死亡。

最终,随着岁月的流逝

,幸存者的体型

将从第一年的餐盘增加到餐桌的大小,至少

在一个物种的情况下
,棱皮龟,大约

十年后。

尺寸带来了
一些保护措施。

现在唯一真正令人担忧的
捕食者是一些较大的鲨鱼物种——

公牛、老虎和白鲨——

以及偶尔出现的虎鲸。

在大约 20 岁时,幸存者的年龄


足以繁殖,

并继续
他们的存在所预示的循环。

在那些从
遥远海滩上的鸡蛋开始的那些中

,现在至少剩下不到 10%

,这是在
重大人为干预之前的可能性。

在过去的一个世纪里,特别是
在过去的几十年里,

人类的努力,从海滩开发

到塑料垃圾再到偷猎、
长线、网,

甚至包括石油在内的有毒化学物质,

都加大了海龟的赌注,

导致它们得以生存。 在每个嵌套循环中,速率下降
到大约 1% 或更低

正是这种增加的人为压力

将八种海龟物种中的每一种都

推向了受威胁
或濒临灭绝的状态。

因为虽然它们已经进化
到克服许多障碍

,但最近的障碍出现得如此之快

且规模如此之大,以至于该物种
发现自己不堪重负。

因此,让我们快速回顾一下这个赔率循环。

使用假设的筑巢季节,

为了方便起见,雌性可能
在一年内筑巢多次,

共 1,000 个卵。

产卵1000个。

800 舱口。

400到水。

200 迈向成年。

20 可以存活到繁殖年龄——

也就是说,没有人为干预。

两个在人为干扰下存活到繁殖年龄

因此,一只正在繁殖的成年海龟
就是远射的体现。

这是例外,而不是规则。

头奖。

在非常真实的意义上,这是

一个奇迹。