It
was on our way home, after finishing the Los Angeles-to-Hawaii
sail race known as the Transpac, when my crew and I first caught
sight of the trash floating in one of the most remote regions
of all the oceans. I had entered my cutter-rigged research vessel,
Alguita, an aluminum-hulled catamaran, in the race
to test a new mast. Although Alguita was built for
research trawling, she was also a smart sailor, and she fit
into the ‘cruising class’ of boats that regularly
enter the race. We did well, hitting a top speed of twenty knots
under sail and winning a trophy for finishing in third place.
Throughout
the race our strategy, like that of every other boat in the
race, had been mainly to avoid the North Pacific subtropical
gyre -- the great high-pressure system in the central Pacific
Ocean that, most of the time, is centered just north of the
race course and halfway between Hawaii and the mainland. But
after our success with the race we were feeling mellow and unhurried,
and our vessel was equipped with auxiliary twin diesels and
carried an extra supply of fuel. So on the way back to our home
port in Long Beach, California, we decided to take a shortcut
through the gyre, which few seafarers ever cross. Fishermen
shun it because its waters lack the nutrients to support an
abundant catch. Sailors dodge it because it lacks the wind to
propel their sailboats.
I
often struggle to find words that will communicate the vastness
of the Pacific Ocean to people who have never been to sea. Day
after day, Alguita was the only vehicle on a highway
without landmarks, stretching from horizon to horizon. Yet as
I gazed from the deck at the surface of what ought to have been
a pristine ocean, I was confronted, as far as the eye could
see, with the sight of plastic.
It
seemed unbelievable, but I never found a clear spot. In the
week it took to cross the subtropical high, no matter what time
of day I looked, plastic debris was floating everywhere: bottles,
bottle caps, wrappers, fragments. Months later, after I discussed
what I had seen with the oceanographer Curtis Ebbesmeyer, perhaps
the world's leading expert on flotsam, he began referring to
the area as the ‘eastern garbage patch.’ But ‘patch’
doesn't begin to convey the reality. Ebbesmeyer has estimated
that the area, nearly covered with floating plastic debris,
is roughly the size of Texas.
My interest in marine debris did not begin with my crossing
of the North Pacific subtropical gyre. Voyaging in the Pacific
has been part of my life since earliest childhood. In 50-odd
years as a deckhand, stock tender, able seaman, and now captain,
I became increasingly alarmed by the growth in plastic debris
I was seeing. 
But
the floating plastics in the gyre galvanized my interest.
I did
a quick calculation, estimating the debris at half a pound for
every hundred square meters of sea surface. Multiplied by the
circular area defined by our roughly thousand-mile course through
the gyre, the weight of the debris was about three million tons,
comparable to a year's deposition at Puente Hills, Los Angeles's
largest landfill. I resolved to return someday to test my alarming
estimate.
Historically,
the kind of drastic accumulation I encountered is a brand-new
kind of despoilment. Trash has always been tossed into the seas,
but it has been broken down in a fairly short time into carbon
dioxide and water by marine microorganisms. Now, however, in
the quest for lightweight but durable means of storing goods,
we have created a class of products – plastics -- that
defeat even the most creative and voracious bacteria.
Unlike
many discarded materials, most plastics in common use do not
biodegrade. Instead they ‘photodegrade,’ a process
whereby sunlight breaks them into progressively smaller pieces,
all of which are still plastic polymers. In fact, the degradation
eventually yields individual molecules of plastic, but these
are still too tough for most anything -- even such indiscriminate
consumers as bacteria -- to digest. And for the past 50 years
or so, plastics that have made their way into the Pacific Ocean
have been fragmenting and accumulating as a kind of swirling
sewer in the North Pacific subtropical gyre.
It
surprised me that the debris problem in the gyre had not already
been looked at more closely by the scientific community. In
fact, only recently starting in the early 1990s -- has the scientific
community begun to focus attention on the trash in the gyre.
One of the first investigators to study the problem was W. James
Ingraham Jr., an oceanographer at the National Oceanic and Atmospheric
Administration (NOAA) in Seattle. Ingraham's Ocean Surface Current
Simulator (OSCURS) predicts that objects reaching this area
might revolve around in it for sixteen years or more.
A year
after my sobering voyage, I asked Steven B. Weisberg, director
of the Southern California Coastal Water Research Project and
an expert in marine environmental monitoring, to help me make
a more rigorous estimate of the extent of the debris in the
subtropical gyre. Weisberg's group had already published an
article on the debris they had collected in fish trawls off
the Southern California Bight, a region along the Pacific coast
extending a 100 miles both north and south of Los Angeles. As
I discussed the design plan for our survey with Weisberg's statisticians,
Molly K. Leecaster and Shelly L. Moore, it became apparent that
we were facing a new problem. In the coastal ocean, bodies of
water are naturally defined, in part, by the coasts they lie
against. In the open ocean, however, bodies of water are bounded
by atmospheric pressure systems and the currents those systems
create. In other words, air, not land, defines the body of water.
Because air pressure systems move, the body of water we wanted
to survey would be moving as well. A random sample of a moving
area such as the gyre would have to be done quite differently
from the way Weisberg's group had conducted their survey along
the Pacific coast.[1]
The
gyre we planned to survey is one of the largest ocean realms
on Earth, and one of five major subtropical gyres on the planet.
Each subtropical gyre is created by mountainous flows of air
moving from the tropics toward the polar regions. The air in
the North Pacific subtropical gyre is heated at the equator
and rises high into the atmosphere because of its buoyancy in
cooler, surrounding air masses. The rotation of the Earth on
its axis moves the heated air mass westward as it rises, then
eastward once it cools and descends at around 30 degrees north
latitude, creating a huge, clockwise-rotating mass of air.
The
rotating air mass creates a high-pressure system throughout
the region. Those high pressures depress the ocean surface,
and the rotating air mass also drives a slow but oceanic-scale
surface current that moves with the air in a clockwise spiral.
Winds near the center of the high are light or even calm, and
so they do not mix the floating debris into the water column.
This huge region, what I call a ‘gentle maelstrom,’
has become an accumulator of debris from innumerable sources
along the North Pacific rim, as well as from ships at sea.
The
subtropical gyres are also oceanic deserts. In fact, many of
the world's land-based deserts lie at nearly the same latitudes
as the oceanic gyres. Like their terrestrial counterparts, the
oceanic deserts are low in biomass. On land the low biomass
is caused by the lack of moisture; in oceanic deserts the low
biomass is a consequence of great ocean depths.
In
coastal areas and shallow seas, winds and waves constantly stir
up and recycle nutrients, increasing the biomass of the food
web. In the deep oceans, though, such forces have no effect;
the bottom sequesters the nutrient-rich residue of millions
of years of near-surface photosynthetic production, as well
as the decomposed fragments of life in the sea, trapping them
miles below the surface. Hence the major source of food for
the web of life in deep ocean areas is photosynthesis.
But
even in the clear waters that prevail in the subtropical gyres,
photosynthesis is confined to the top of the water column. Sunlight
attenuates rapidly with depth, and by the time it has gone only
about 5% of the way to the bottom, the light is too weak to
fuel marine plants. The net effect is a vast area poor in resources,
an effect that makes itself felt throughout the food web. Top
predators, such as tuna and other commercially viable fish don't
hang out in the gyres because the density of prey is so low.
The human predator stays away too: the resources that have drawn
entrepreneurs and scientists alike to various regions of the
ocean are not present in the subtropical gyres.
What
does exist in the gyres is a great variety of filter-feeding
organisms that prey on the ever-renewed crop of tiny plants,
or phytoplankton. Each day the phytoplankton grow in the sunlit
part of the water, and each night they are consumed by the filter
feeders, a fantastic array of alien-looking animals called zooplankton.
The zooplankton include chordate jellyfishes known as ‘salps,’
which are among the fastest-growing multicellular organisms
on the planet. By fashioning their bodies into pulsating tubes,
the salps are able, each day, to filter half the water column
they inhabit, drawing out the phytoplankton and smaller zooplankton
for food. But salps are gelatinous creatures with a low biomass,
and so there is no market for them. Hence the realm they dominate,
one of the largest uniform habitats on the planet, remains unexploited
and largely unexplored.
Molly Leecaster, Shelley Moore and I came up with a plan to
make a series of trawls with a surface plankton net, along paths
within a circle with a 564 mile radius. The area of the circle
would then be almost exactly 1 million square miles. Trawling
would start when we estimated we were under the central pressure
cell of the high-pressure system that creates the gyre. We would
regard the starting point as the easternmost point along the
circumference of the circle. Then we would proceed due west
to the center of the circle, turn south, and sail back to the
southernmost point on the circumference, alternating between
trawling and cruising. We intended to obtain transect samples
with random lengths and random spacing between trawls. To be
conservative about our sampling technique, we decided that any
debris we collected would count only as a sample of the debris
within the area of the transected circle.
In
August 1998, I set out with a four-member volunteer crew from
Point Conception, California, heading northwest toward the subtropical
gyre. Onboard Alguita was a manta trawl, an apparatus
resembling a manta ray with wings and a broad mouth, which skimmed
the ocean surface trailing a net with a fine mesh. Eight days
out of port, the wind dropped below ten knots and we decided
to practice our manta trawling technique, taking a sample at
the edge of the subtropical gyre, about 800 miles offshore.
We pulled in the manta after trawling three and a half miles.
What
we saw amazed us. We were looking at a rich broth of minute
sea creatures mixed with hundreds of colored plastic fragments
-- a veritable plastic-plankton soup. The easy pickings energized
all of us, and soon we began sampling in earnest. Because plankton
move up and down in the water column each day, we needed to
trawl nonstop, day and night, to get representative samples.
When we encountered the light winds typical of the subtropical
gyre, we deployed the manta outside the port wake, along with
two other kinds of nets. Each net caught plenty of debris, but
far and away the most productive trawl was the manta.
There
was plenty of larger debris in our path as well, which the crew
members retrieved with an inflatable dingy. In the end, we took
about a ton of this debris on board. The items included:
On
Midway Island in the Hawaiian chain, a bolus, or mass of chewed
food, coughed up by one bird included many identifiable objects.
By contrast, a bird on Guadalupe Island, which lies 150 miles
off the coast of Baja California, produced a bolus containing
only plastic fragments. The principal natural prey of both bird
colonies is squid, but as the ecologist Carl Safina notes in
his book, Eye of the Albatross, the birds' foraging style can
be described as "better full than fussy." Robert W.
Henry III, a biologist at the University of California, Santa
Cruz, and his colleagues have tracked both the Hawaiian and
the Guadalupe populations of birds and found that the foraging
areas of each colony in the Pacific are generally non-overlapping
and wide apart.
One
difference between the two areas is apparently the way debris
flows into them. In Ingraham's OSCURS model, debris from the
coast of Japan reaches the foraging area of the Hawaiian birds
within a year. Debris from the West Coast of the United States,
however, sticks close to the coast until it bypasses the foraging
area of the Guadalupe birds, then heads westward to Asia, not
to return for six years or more. The lengthy passage seems to
give the plastic debris time to break into fragments.
The subtropical gyres of the world are part of the deep ocean
realm, whose ability to absorb, hide, and recycle refuse has
long been seen as limitless. That ecologically sound image,
however, was born in an era devoid of petroleum-based plastic
polymers. Yet the many benefits of modern society's productivity
have made nearly all of us hopelessly, and to a large degree
rationally, addicted to plastic. Many, if not most, of the products
we use daily contain or are contained by plastic. Plastic wraps,
packaging and even clothing defeat air and moisture and so defeat
bacterial and oxidative decay. Plastic is ubiquitous precisely
because it is so good at preventing nature from robbing us of
our hard-earned goods through incessant decay.
But
the plastic polymers commonly used in consumer products, even
as single molecules of plastic, are indigestible by any known
organism.
