Chapter 17Marine Resources

OceanographyOceanographyAn Invitation to Marine Science, 7thAn Invitation to Marine Science, 7th

Tom GarrisonTom Garrison

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).

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.

Petroleum and Natural Gas Are the Ocean’s Most Valuable Resources

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.

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.

The Ocean’s Most Valuable Biological Resources

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.