Food, Soil, and Pest Management - Environmental Science - page 226

networks of no-take reserves. However, implementing
such strategies costs money and is often politically
unpopular.

fish are then released, and adults are harvested when
they return to spawn.
Figure 10-24 lists the major advantages and dis-
advantages of aquaculture. Some analysts project that
freshwater and saltwater aquaculture production could
provide at least half of the world's seafood by 2020.
Other analysts warn that the harmful environmental ef-
fects of aquaculture could limit future production.
Figure 10-25 lists some ways to make aquaculture
more sustainable and to reduce its harmful environ-
mental effects. However, even under the most opti-
mistic projections, increasing both the wild catch and
aquaculture will not increase world food supplies sig-
nificantly. The reason: Fish and shellfish supply only
about 1% of the calories and 6% of the protein in the
human diet.

Economics and Politics: Should Governments
Continue Subsidizing Fishing Fleets?
Government subsidies given to the fishing industry
are a major cause of overfishing.
Overfishing is a big and growing problem because too
many commercial fishing boats and fleets are trying to
hunt and gather a dwindling supply of the most desir-
able fish.
It costs the global fishing industry about $120
billion per year to catch $70 billion worth of fish. Gov-
ernment subsidies such as fuel tax exemptions, price
controls, low-interest loans, and grants for fishing gear
make up most of the $50 billion annual deficit of the
industry. Without such subsidies, some of the world's
fishing boats and fleets would go out of business and
the number of fish caught would approach their sus-
tainable yield.
Continuing to subsidize excess fishing allows
some fishers to keep their jobs and boats a little longer
while making less and less money until the fishery col-
lapses. Then all jobs are gone, and fishing communi-
ties suffer even more—another example of the tragedy
of the commons in action. Critics call for shifting some
of the money from subsidies to programs to buy out
some fishing boats and retrain their crews for other
occupations.

Economics and Politics: Government
Agricultural and Food Production
Governments can use price controls to keep food
prices artificially low, give farmers subsidies to
encourage food production, or eliminate food price
controls and subsidies and let farmers and fishers
respond to market demand.

T rade-Offs

Aquaculture

Advantages

Disadvantages

x

H OW W OULD Y OU V OTE ? Should governments eliminate
most fishing subsidies? Cast your vote online at http://biology
.brookscole.com/miller11.

Highly efficient Large inputs of

land, feed, and
water needed

High yield in
small volume
of water

Produces large
and concentrated
outputs of waste

Science: Aquaculture—Aquatic Feedlots
Aquaculture, the world's fastest-growing type of food
production, has advantages and disadvantages.
Aquaculture involves raising fish and shellfish for
food like crops instead of going out in fishing boats
and hunting and gathering them. The world's fastest-
growing type of food production, it accounts for about
one-third of the fish and shellfish we eat. China, the
world leader in this field, produces more than two-
thirds of the world's aquaculture output.
There are two basic types of aquaculture: fish
farming and fish ranching. Fish farming involves cul-
tivating fish in a controlled environment (often a
coastal or inland pond, lake, reservoir, or rice paddy)
and harvesting them when they reach the desired size.
Fish ranching involves holding anadromous spe-
cies, such as salmon that live part of their lives in fresh
water and part in salt water, in captivity for the first
few years of their lives, usually in fenced-in areas or
floating cages in coastal lagoons and estuaries. The

Increased yields
through crossbreeding
and genetic
engineering

Destroys mangrove
forests and
estuaries

Increased grain
production needed
to feed some species

Can reduce
overharvesting
of conventional
fisheries

Fish can be killed
by pesticide runoff
from nearby cropland

Little use of fuel

Dense populations
vulnerable to disease

Profits not tied to
price of oil

Tanks too
contaminated to use
after about 5 years

High profits

Figure 10-24 Trade-offs: advantages and disadvantages of
aquaculture. Critical thinking: pick the single advantage and
disadvantage that you think are the most important.