Troubled Seas

Ninety percent of the big fish have already been caught. Will rampant
overfishing cause the ocean’s ecosystems to collapse? No one knows.

THAT DAY THE CREW managed to pull up a small haul of creaturesspider
fish and long-legged crabs and others known to frequent seamounts. Two
of them looked especially odd: a dragonfish, less than seven centimeters
long, that had a barbel-like protrusion on its chin with a light organ
at its tip, probably for attracting prey; and a type of grenadier fish
with distinctive markings and coloration. That evening, an addendum to
the ships log referred to two species new to science.
New to science the phrase is usually accompanied by the sound of popping
corks. But marine biologists are spoiled for diversity: the Australians
and New Zealanders on the Tangaroa came back with more than 100 possibly
new species. Thats less a sign of the oceans profusion than of our
ignorance: scientists know shockingly little about what makes the oceans
tick. Only in the past decade or so have marine biologists taken an
interest in seamounts, where strong currents bearing precious nutrients
and oxygen tend to support abundant marine life; of thousands scattered
throughout the world’s oceans, they’ve visited only a handful.
Whaling: The Battle Isn’t Over
The problem is that what we do know is frightening. While the Tangaroa
was plying the Tasman Sea, Canadian biologists Ransom Myers and Boris
Worm of Dalhousie University in Halifax were publishing, in the journal
Nature, the latest and most comprehensive estimate of the state of the
world’s fisheries. Scientists have known for more than a decade that
fish are being removed from the ocean faster than they can replenish
themselves. But Myers and Worm have now attached a shocking figure to
the debate: in the past 50 years, they say, overfishing has removed nine
of 10 large predatorsthe big fish like tuna and cod. Scientists have
sounded similar alarms for years, but always about this fishery or
thatthe North Atlantic in the 1980s, the North Sea and the waters off
Japan in the 1990s and, more recently, western Africa. This time, the
data is global. The beauty of the paper is that it has a nice, round
number,says Jeremy Jackson, a scientist at the Scripps Institution of
Oceanography in San Diego. Ninety percent of the worlds fish are gone.
Anybody can understand that.

Can we? Ask most marine biologists, and they’ll tell you that the more
they learn about the oceans, the less they know. Eliminating predatory
fish is bound to have wide-ranging repercussions. You cant just remove
the top layer of an ecosystem without having a knock-on effect,says
Larry Crowder, a Duke University biologist. As a worst-case scenario, it
could eventually turn the oceans into deserts. But this is unexplored
territory, and scientists are fumbling around like the Tangaroa with its
dredge. What would the oceans be like without predators?says Barbara
Block, a marine biologist at Stanford University. Its like asking what
Africa would be without lions. What it means is almost completely
unknown right now.What’s undisputed is the need to answer this question,
and soonnot least to build the political case for preserving the last
earthly frontier.

If you didn’t know where to look, the deep oceans might seem to be
almost devoid of life. Beyond the narrow continental shelves, the ocean
bottom drops to tens of thousands of meters. At such depths, pressures
reach 1,000 atmospheresenough to compress a human body down to the size
of a doll. Be-cause the suns rays cant penetrate beyond a few meters of
seawater, energy and nutrients at the ocean floor are few and far
between.

Bottom dwellers, like sea cucumbers, clams and bristle worms, live slow,
monotonous lives of minimal activity.

As if to make up for this dreary vastness, the oceans support the
occasional oasis. Warm currentslike the Gulf Stream in the Atlantic, or
the Kuroshio Current off Japancollide with cooler water, creating a
discontinuity, like oil and water, that traps tiny phytoplankton.
Zooplankton arrive to eat them, small fish come to eat the zooplankton
and the big fish, the turtles, the seabirds follow in turn. A similar
proliferation occurs on seamounts, on the continental shelves and at
upwellings of cold water from the deep. The paucity of sunlight,
nutrients and oxygenthe very thing that makes the ocean so
forbiddingalso imposes a structure on marine life.

The propensity of life to congregate is one reason scientists worry
about overfishing. The oceans may be vast, but the number of oases is
finite. In the Grand Banks in the northern Atlantic, for instance, cod
were plentiful a hundred years ago. Then fishing trawlers came in the
early 20th century and, 50 years later, factory trawlersmammoth ships
that can net, fillet and freeze enormous amounts of fish. In a few
decades, the fisheries were depleted. In 1992 the Canadian government
was forced to impose a moratorium on cod fishing, but in 11 years the
cod have not come back. Nobody knows why.

With the decline of shallow-bottom feeders like cod and halibut, the
fishing industry has redoubled its efforts in the open oceans. The
preferred method is so-called longline fishing, which entails stringing
out lines, supported by buoys, that stretch tens of miles over the
waters surface, and attaching other lines with baited hooks. The
technique is particularly effective for tuna, billfish and swordfish.
(It also nabs sea turtles, sharks and albatrosses, and is a major factor
in the decline of these animals.) Myers and Worm studied historical data
from longline fish-ing going back more than 50 years and found that
catch rates for all types of fish had dropped more precipitously than
scientists previously thought.

The report is the first documented decline of predators throughout both
coastal and deep ocean waters. Stanfords Block thinks thats not merely a
question of fishermen ranging farther afield. Since 1996 she has studied
the migratory patterns of tuna and sharks, tracking them with satellite
transponders. Shes found that unlike cod, tuna and sharks dont confine
themselves to any one area. Sharks off the western United States have
been observed swimming the 3,700km to Hawaii. Block once traced an
Atlantic bluefin tuna as far north as Iceland, as far south as the
Caribbean, and even to the Mediterranean. We cannot tell you where
almost any of these species go to feed or breed,she says.

On the one hand, that means the oceans are interrelatedand thus that the
removal of predators can have far-reaching effects. But it reveals
nothing about the lower layers of the food chain. Scientists have only
piecemeal examples of what happens when marine eco-systems become
unbalanced. The collapse of the cod fisheries in the North Atlantic has
been a boon to shrimp and sea urchins, the cod’s prey. It’s given
urchins free rein to devour the kelp forests, turning vast stretches of
the sea floor into urchin barrens.In a study of coastal ecosystems two
years ago, Jackson found overfishing of predators, rather than pollution
and global warming, to be the probable cause of oceanic dead zonesareas
of complete ecosystem collapse, where microbes fill the void left by
fish and invertebrates.

Dead zones are found in the Gulf of Mexico, Chesapeake Bay and the
Baltic and Adriatic seas, and theyre spreading to the open oceans.
Coral reefs in the Caribbean have been hurt by overfishing of
algae-eating fish, such as parrot fish. Sea urchins took up the slack
for years, but when a disease outbreak wiped them out the corals grew
fuzzy and green with algae, and died.

Since so little is known about marine ecosystems, scientists are
reluctant to speculate where all this might lead. It doesn’t take much
imagination, though, to extrapolate from what we do know. If overfishing
continues for the big predators, its possible that many of them may fall
below a critical mass and lose the ability to reproduce, sending
populations into a downward spiral. That would throw millions of people
who depend on the fishing industry out of work. If the cod and herring
fisheries are any guide, the damage would take decades to reverse. It
would be a global crisis; treaties would be signed; the United Nations
would be granted the power to enforce fishing bansand wed all wait out
the decades hoping the fish would return. But they might not, ever. The
removal of so many big fish could have a ripple effect, killing off
invertebrate and microbial life forms we havent even heard of yet, but
which serve as essential links in the food web. How long would it take50
years? 100?to find that cod, tuna, halibut, mackerel, marlin and other
big fish were creatures only of farms or museums?

This is speculation, but it isn’t idle speculation. The Myers and Worm
data may be telling us that a global catastrophe is already underway.
It sounds laughable to put it this way. It would have been laughable,
too, to suggest a hundred years ago that fishermen would someday catch
the last Atlantic cod. Cod, as everybody knew, was as close to a
limitless resource as you could get. Maybe then. But tens of thousands
of unemployed Canadian fishermen have been waiting a decade for the cod
to return to the waters of Labrador and Newfoundland. Earlier this year,
Canada put the Atlantic cod on its endangered-species list.

The public hasn’t much noticed the decline. More fish are being raised
on farms, and fishing boats have pushed farther and deeper in chase of a
dwindling catch. The dearth of tuna isn’t yet reflected in the price of
a tuna sandwich. But the decline is having some impact. Mahi-mahi has
appeared on the menus of Western restaurants, as a replacement for
swordfish. Fishing boats are plying treacherous Antarctic waters for the
Patagonian toothfish, known by its more salubrious moniker, Chilean sea
bass.

Relatively simple fixes, such as enforceable quotas on fishing nations,
could halt the damage to the worlds fisheries. The problem is, the
oceans are largely a free-for-all. We manage fish on a
species-by-species basis and we manage on a crisis basis,says Leon
Panetta, who headed the Pew Charitable Trust’s recent report on the
worlds fisheries. We have to approach the management of all fisheries in
an ecosystem type of approach.And yet, neither the United Nations nor
the big environmental groups have found an effective way to address
overfishing.

Barring drastic action, the world is headed for an environmental
disaster whose proportions are unknown. What’s most depressing,says
Jackson, is there’s no new frontier. The ocean has had it.And we may
never know what we’re missing.
With Kristin Kovner and Emily Flynn
© 2003 Newsweek, Inc.