Fish section of an international grocery store in Virginia. Photo by Ken Hammond, USDA |
Seafood is one of the most important and healthy parts of
the human diet. Eating fish supplies us with proteins
as well as amino
acids and omega
fatty acids that are essential for healthy tissues. Worldwide,
people get twice as much of their animal protein from seafood
(fish, shrimp, and shellfish) as they do from beef.
Source: BBC News Online |
Nearly a billion people, especially
in developing countries, rely on fish as their chief source
of proteins.
FLOATING FACTORIES
Some fish are still caught in the wild, and are probably
the only animals in our regular diet that live in the wild.
Catching them can be tough work. In fact, commercial fishing
is one of the most dangerous jobs in the United States. For
a look at life aboard a Maine fishing boat, check out A
Diary of Danger on the Seas.
Fishing crew on the Indian Ocean. Photo by
Jose Cort, NOAA |
Like farms on land, modern fishing has become highly industrialized.
Some of today's fishing "boats" are longer than a football
field! These fishing factories, using fast boats and efficient
netting methods, can capture fish from deeper and deeper parts
of the ocean and from larger areas of the ocean. Such ships
often work in fleets comprising "catching vessels" (which
haul in the fish) and a "mother ship" (which processes them).
Many of these factory fleets quick-freeze their catches while
still at sea. Workers clean the fish, then freeze them almost
instantly. Such frozen-at-sea (FAS) fish still have water
in their tissues, which helps protect their flavor. Indeed,
FAS fish may actually be tastier and healthier than "fresh"
fish sold a few days after being caught.
FISHING FOR
TROUBLE
"From giant blue marlin to mighty bluefin tuna, and from
tropical groupers to Antarctic cod," biologist Ransom Myers
told National
Geographic News, "industrial fishing has scoured the global
ocean." Myers and other scientists argue that larger fish,
of all types, have been particularly decimated, with catches
yielding 90 percent fewer large fish now than in 1950.
Likewise, the average size of many kinds of fish is declining.
Twenty years ago, the average swordfish brought to market
weighed 120 kilograms. Today it's 30 kilograms—one-quarter
the previous weight. There has been recent hope for swordfish,
however, as you can learn from the sidebar at the right.
United Nations findings are similarly bleak. The UN classifies
two-thirds of the world's fishing areas as "fully exploited"
or "overexploited." In many areas, overfishing has been so
drastic that not enough fish remain to mate and renew the
population. This is called recruitment overfishing.
Cod, the key ingredient in Britain's beloved fish-and-chips,
offers an example of a fish in hot water. The North Sea, which
lies to the east of Great Britain, was once a prime site for
catching cod. Now fishing crews are lucky to catch even a
tenth of what they could haul in 30 years ago. Even using
satellite-tracking equipment and other sophisticated technology,
fishing fleets have trouble finding cod. The situation is
even worse in the Grand Banks, off the eastern shores of Canada.
The last commercially-significant cod there vanished in the
early 1990s.
Recruitment overfishing appears to be one of the main culprits.
Most cod caught these days are 2-4 years old. That's
too young to have reached sexual maturity.
Chilean Sea Bass are also affected by market demand. They
normally live as many as fifty years, but pirate fishermen
who ignore government regulations catch huge numbers of these
fish—called "white gold" because of their popularity
with consumers—before they have an opportunity to reproduce.
The result: dramatic declines in the Chilean Sea Bass population.
FISH FARMING
Have you ever wound up thinking, "Well, it seemed like a
good idea at the time?" That's the way some people feel
about fish farming, also known as aquaculture (and sometimes
mariculture). Like farmers on land raise cattle and chicken,
people are raising fish, shrimp, and oysters, under controlled
conditions in contained areas, either in ponds on shore or
in netpens(net cages) located in bays or in the open sea.
Fish farm in Thailand. Photo by R.
Faidutti, United Nations |
Since the 1970s, aquaculture has been the fastest growing
sector of animal food production in the world. As of 2003,
fish farms provided nearly a third of all seafood consumed
by humans. Farmed fish have also become an important source
of protein for animal feeds.
Does aquaculture have its merits?
Yes and no. Aquaculture advocates point out that it's
an essential tool for feeding the world's growing population,
especially in developing countries, and that fish farms offer
an alternative to overfishing the oceans. The overall impact
of fish farming depends on the species, how it's raised
and fed, and where the farm is located. Tilapia, for example,
is a plant-eating fish raised on farms, that doesn't
harm the environment.
On the other hand, most aquaculture introduces new problems:
- Producing fish pellets to feed fish in fish farms requires
catching, and potentially depleting, "fish food" species.
- Fish food may have high levels of contaminants, including
persistent organic pollutants such as PCBs and pesticides.
- Creating space for fish farms often destroys other ecosystems
and threatens biodiversity. Southeast Asians, for instance,
have cleared thousands of acres of marshes and mangrove
forests that grew at the water's edge. These forests—now
replaced by shrimp farms—had served as natural coastal
barriers and home to native fishing communities. Learn more
about mangroves at San Diego Museum of Natural History's
Ocean
Oasis.
- Crowding huge numbers of fish into a pen can breed disease.
To fight disease, fish farmers rely heavily on antibiotics
and chemicals, that escape ponds and pens and seep into
open waters.
- Fish waste disrupts natural aquatic systems. Experts estimate
that a 200,000-fish salmon farm generates as much waste
as a 600,000-person city (without a sewage system).
- Farm fish can escape through breaks in the nets and wreak
havoc on local ecosystems by competing with natural wild
fish for food and reproduction.
Find out more about fish farming at Seafoodwatch.
WHAT CAN WE DO?
Curbing the widespread growth of aquaculture and dealing
with the problems related to overfishing can seem insoluble.
But, scientists have identified various actions that would
help improve matters:
- Governments can make and enforce limits on the amount
and size of wild fish that are caught.
- Nets, designed with larger mesh, allow small fish, nonfood
fish, such as dolphins, to escape and reproduce. (Undesireable
and discarded catch, called bycatch, increasingly depletes
the sea's wildlife.)
- Improving the design and management of aquaculture facilities
can reduce and prevent disease and avoid reliance on antibiotics.
- Developing plant-based food for farm fish would reduce
the need to capture "fish food" species.
- Ecolabels and other government policies can encourage
consumers to buy seafood produced via organic aquaculture
which does not use chemicals and antibiotics, and allows
fish to live in clean, healthy water.
Mulberry bushes surround, and benefit from,
Chinese fishponds. Photo by H. Zhang, United Nations |
- The ancient practice of polyculture, raising fish, plants,
and animals near each other, could make it easy to use fish
wastes to fertilize plants. So would hydroponics, or growing
plants in water instead of soil.
One person has given all of us a new way to make a difference.
While doing field research around the world, Smithsonian Institution
marine biologist Carole Baldwin became highly concerned about
what she saw. Baldwin decided to help solve the worldwide
problem of overfishing by creating recipes for the dinner
table. The book (One Fish, Two Fish, Crawfish, Bluefish:
The Smithsonian Sustainable Seafood Cookbook) focuses
on fish that are fished or farmed in an ecologically-sound
manner, and are not endeangered. From a list of 230 fish species
in the U.S. that passed her ecology test, she narrowed the
list to 96, and sent it to chefs across the U.S. to ask for
recipes. The theory: If people select from a broad range of
well-managed species, then we can help relieve the burden
on overfished species and prevent others from being fished
out.
|
Things looked grim for North Atlantic swordfish
in 1999. Decades of 
