Oceans in Crisis - Ocean Worlds: The Story of Seas on Earth and Other Planets - page 164

sued over it), but amid the tales of battle and plunder there is also a
picture of a virgin sea.
Green sea turtles then, he said, abounded to the extent that ships,
when losing their bearings, could navigate by the sounds they made
as they swam in countless numbers to the islands to lay their eggs.
Today, there are few green turtles. But can a pirate be a reliable source?
Take Charles Darwin, then, a century and a half later. Arriving at the
Galapagos islands, he noted that the bay where he landed was 'swarm-
ing' with fish, shark, and turtles 'popping their heads up in all parts'.
Among the fish he noted as particularly common was the local spe-
cies of grouper. It is now on the Red List of endangered species.
The sea used to be thought of as an endless, inexhaustible resource.
No more. They are now, as regards fish, unrecognizable from their
original pristine state. In fact, their pristine state is now something of
a mystery, because overfishing before the days of scientific records
had already changed the baseline so much that we do not know what
pristine is. The fisheries scientist Daniel Pauly has called this the
'shifting baseline' syndrome. Hence, the value of the old anecdotes in
giving us an idea, however imprecisely, of what the oceans used to
be like. 91
By any measure, the story of decline is all too clear. It is the top of
the oceanic food chain that has seen the most change. Take sharks,
for instance. There are few creatures that induce more visceral dread
in humans. Yet sharks have been a key part of the marine food chain
for more than 400 million years. Their fall has been dramatic. In the
north-west Atlantic, for instance, declines in almost all shark spe-
cies exceeded 50 per cent (while some were over 75 per cent)—and
that is in just 15 years or less at the end of the twentieth century,
since when the plunder has continued largely unabated. 92 This fol-
lows the already substantial declines from previous fishing (that
shifting baseline again), and so the real declines exceed 90 per cent,