Transcript Garrison Oceanography 7e Chapter 17

Oceanography
An Invitation to Marine Science, 7th
Tom Garrison
Chapter 17
Marine Resources
Chapter 17 Study Plan
• Marine Resources Are Subject to the Economic
Laws of Supply and Demand
• Physical Resources Are Useful Substances from
the Ocean or Seabed
• Energy Can Be Extracted from the Motion of
Seawater
• Marine Biological Resources Are Being Harvested
for Human Use
• Non-extractive Resources Use the Ocean in Place
• The Law of the Sea Governs Marine Resource
Allocation
Chapter 17 Main Concepts
• By most calculations, we have used more natural
resources since 1955 than in all of recorded human history
up to that time.
• Petroleum and natural gas are the ocean’s most valuable
resources.
• The contribution of marine animals and plants to the
human intake of all protein is small, probably around 4%.
• Fish provide more than 2.9 billion people with at least 15%
of their average per capita animal protein intake.
• The International Law of the Sea nominally governs
marine resource allocation.
• With very few exceptions, our present level of growth and
exploitation of marine resources is unsustainable.
Marine Resources Are Subject to the
Economic Laws of Supply and Demand
• How are marine resources classified?
– Physical resources – result from the deposition, precipitation, or
accumulation of useful substances in the ocean or seabed.
– Biological resources – living animals and plants collected for human use.
– Marine energy resources – result from the extraction of energy directly
from the heat or motion of ocean water
– Non-extractive resources – uses of the ocean in place – transportation of
people and commodities by sea, recreation, and waste disposal.
• Resources can be further classified as renewable or
nonrenewable.
– Renewable resources – naturally replaced by the growth of marine
organisms or by other natural physical processes
– Nonrenewable resources – oil, gas, and solid mineral deposits are present
in the ocean in fixed amounts and cannot be replenished over time spans as
short as human lifetimes.
Petroleum and Natural Gas Are the
Ocean’s Most Valuable Resources
World energy
consumption from
1970 to 2025 (as
projected by the
United States
Department of
Energy).
Petroleum and Natural Gas Are the
Ocean’s Most Valuable Resources
Physical resources result from
the deposition, precipitation, or
accumulation of useful substances
in the ocean or seabed. Most
physical resources are mineral
deposits, but petroleum and natural
gas, mostly remnants of once-living
organisms, are included in this
category. Fresh water obtained
from the ocean is also a physical
resource.
(left) Oil and natural gas are often
found together beneath a dome of
impermeable caprock. Or adjacent
to intruding domes of salt.
Oil and gas are not found in vast
hollow reservoirs, but within pore
spaces in rock. The pressure of
natural gas and compression by
the weight of overlying strata drive
oil through the porous rock and
toward the drill pipe.
Waves and Currents Can Be
Harnessed to Generate Power
Large tubes
flexed by ocean
waves may
someday be used
to generate
electricity.
Power Can Be Generated from the
Ocean’s Vertical Thermal Gradient
Basic aspects of the
thermal energy
conversion system
first proposed by
Jacques d’Arsonval in
the 1880s..
The Ocean’s Most Valuable
Biological Resources
The top five marine fish-harvesting nations
and the top marine fishing areas in 2004.
The Ocean’s Most Valuable
Biological Resources
Growth of the worlds live capture
and aquaculture/mariculture
fisheries. Note that with the
exception of China, world output
has remained relatively constant
since about 1987, whereas the
growth of China’s fisheries
through the last two decades can
best be described as “explosive.”
Aquaculture is the growing or
farming of plants or animals in a
water environment under
controlled condition.
Mariculture is the farming of
marine organisms, usually in
estuaries, bays, or nearshore
environments or in specially
designed structures using
circulated seawater.
The Ocean’s Most Valuable
Biological Resources
(above) Stern trawler fishing. After sonar on the trawler
finds the fish, they’re captured by a trawl net more than 122
meters (400 feet) wide. Boards angled to the water flow
keep the net’s mouth open. The largest nets extend about
0.8 kilometer (1/2 mile) behind the towing vessel and are
large enough to hold a dozen 747 jetliners.
Today’s Fisheries Are Not
Sustainable
• What are some key terms and ideas about fishery
management?
• Maximum sustainable yield – the maximum amount
of any species that can be harvested without affecting
future yields
• Overfished – the status assigned to fish stocks that
have been harvested so there is not enough breeding
stock left for replenishment
• Commercial extinction – the depletion of a species to
the point where it is no longer profitable to harvest
• Bykill – animals unintentionally killed when other
species are being harvested
Whaling Continues
Commercial slaughter of the
five largest whale species,
1940-85. All five species
included in this graph are
commercially extinct, and the
blue whale is still in danger of
total extinction even though
commercial blue whale hunting
ended in 1964. At that time only
about 1,000 blue whales were
left, and experts fear that the
population may have been too
small to recover.
The United Nations Formulated
The International Law of the Sea
• The Law of the Sea is an international
agreement that governs the use of the world
ocean.
• The United States Exclusive Economic
Zone is a 10.3 million square kilometer
region of ocean on the coastal margin that
the United States unilaterally claims
sovereign rights to and jurisdiction of.
The U.S. Exclusive Economic Zone
Extends 200 Nautical Miles from Shore
The U.S. Exclusive Economic Zone (EEZ) is shown in red. Note how
much of the EEZ is associated with distant possessions. Other
Exclusive Economic Zones are shown in blue.
Seafood Recommended To Be
Used or Avoided
List of seafood recommended to be used or avoided. Visit
http://www.montereybayaquarium.org for updates to this
information.
Chapter 17 in Perspective
In this chapter you saw two sides of humanity’s use of the ocean. On the one
hand, we find the ocean’s resources useful, convenient, and essential. On the
other, we find we cannot exploit those resources without damaging their source.
World economies are now dependent on oceanic materials, and we are
unwilling to abandon or diminish their use until we see unmistakable signs of
severe environmental damage. By then, mitigation is usually too late.
Marine resources include physical resources such as oil, natural gas, building
materials, and chemicals; marine energy; biological resources such as seafood,
kelp, and pharmaceuticals; and non-extractive resources like transportation and
recreation. The contribution of marine resources to the world economy has
become so large that international laws now govern their allocation. In spite of
their abundance, marine resources provide only a fraction of the worldwide
demand for raw materials, human food, and energy. Similar resources on land
can usually be obtained more safely and at lower cost. The management of
marine resources – especially biological resources – for long-term benefit has
been largely unsuccessful.
In the last chapter you will learn that humanity has embarked on an
unintentional global experiment in marine resource exploitation and waste
management. We hesitate to adjust course as we rush into the unknown.