Chapter 12 Oceans and the Environment

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Chapter 12Oceans and the Environment

Big Question Can We Learn to Manage the Oceans
Resources?
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Earth is the Water and Ocean Planet
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World Fish Production

• Estimated 27,000 species of fish and shellfish
  live in oceans
• Fish are main source of animal protein for 1
  billion people

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• Worlds total fish harvest increased greatly
  since the mid-20th century
• Increase in total worlds fish catch is from
  aquaculture
• The catch is not sustainable if we catch more
  than are replaced

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The Decline of Fish Populations

• Fishing is an international trade
• Which fish are the most threatened?
• - codfish, flatfishes, tuna, swordfish,
  sharks, and rays
• Why care about endangered sharks?

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• Its getting harder to catch fish
• The evidence for declining fish populations
• - Number of marine fish caught with lines
  and hooks

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• Case Study Chesapeake Bay
• - A fishery disaster
• in U.S.
• - Food chains in bay
• are complex

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• Other problems
• - i.e. highly polluted farm runoff
• Scientific theory remains inadequate

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• Science-based management has failed to conserve
  fisheries
• Problems calculating maximum sustainable yield
• Fisheries are an open international resource
  Tragedy of the Commons
• Exploitation of new fisheries before scientific
  assessment
• Harvesting gear is destructive to habitat

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• Bycatch the taking of non-target species

shrimp trawl catch, shrimp trawling results in
tremendous bycatch and waste, up to 12 times
bycatch for 1 lb of shrimp, Texas, USA, Gulf of
Mexico
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An Ocean Is Many Habitatsand Ecosystems

• Habitats and ecosystems
• - intertidal areas, saltwater marshes, sandy
  shores, continental shelves, upwellings, open
  oceans, coral reefs, the deeps, hydrothermal
  vents

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Ocean Currents

• Global circulation of currents ocean conveyor
• The Gulf Stream famous upper warm current

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Worlds Ocean Conveyor Belt
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Where Are the Fish?

• Most fish we eat come from continental shelves

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• Upwelling ocean currents stimulate the food chain
• They bring nutrients, i.e. phosphorus, from deep
  ocean sediments and waters

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• Prevailing winds create upwellings
• Failing of upwellings off Peru are El Niño events

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El Nino

• Describes a relationship between ocean currents
  and terrestrial climate
• La Nina - A pool of warm ocean water in the
  Pacific, normally drives a heavy rain system over
  S.E. Asia and Australia, and at the same time
  drives upwelling of cold waters in Central and
  South America.
• Vs El Nino (Christ child) Warm water surges
  east and interferes with upwelling.
• May get more extreme and frequent due to human
  impacts

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Where Are the Fish?

• Fish are abundant where food is abundant
• Intertidal habitat is teeming with life
• Near-shore habitats are most susceptible to land
  pollution
• Disturbances are frequent in intertidal zones

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• Upper open ocean (pelagic region) often has low
  biological diversity
• Ocean bottom (benthos region) remains relatively
  little known
• Hydrothermal vents occur in deep ocean locations

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Coral Reefs A Special Problem

• Reefs are restricted to warm waters and therefore
  low latitudes

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• We love them to death
• More than half of the remaining coral reefs are
  considered at risk

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Reefs and Ecological Diseases
Black-band disease, attacks corals and the source
may be pathogenic bacteria from human feces
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We Pollute the Oceans

• Our wastes end up in the oceans

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• Marine pollution affects oceanic life in a
  variety of ways
• Plastics
• - Are dumped into
• oceans
• - Float with ocean
• currents
• - Accumulate in
• convergent currents
• i.e. northwestern
• Hawaiian Islands

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• Wildlife live among the debris
• What can we do about this problem?

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Marine Sanctuaries

• Sanctuaries can be invaluable in helping
  populations recover

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Marine Sanctuaries

• Shelter marine organisms from destructive harvest
  methods.
• Protection problems.
• Vast areas.
• Difficulty to hinder entrance to a marine park.
• Terrestrial/Up-stream impacts

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• Unfortunately, sustainable harvesting of wild
  biological resources usually isnt profitable
• Therefore farm fish - aquaculture

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Aquaculture and Mariculture

• Freshwater aquaculture and ocean mariculture is
  growing rapidly
• Could be a major solution of nutritional quality
• Aquaculture is not a new idea

Carp
Tilapia
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• Mariculture has grown rapidly and will likely
  continue
• Example Oysters and mussels grown on ocean rafts

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• Aquaculture can create its own environmental
  problems
• destroys sensitive habitats
• excrement and excess food of farmed
• organisms pollute habitat of wild
  organisms
• disease prevention is difficult
• contaminate wild fish stocks with foreign genes
  or diseases, or the production of less
  genetically fit strains
• take of wild fish for fish pellets
• export doesnt help food-deficient countries
• Benefits Fish are grown in smaller spaces, less
  expense/risk in collection, higher volume for
  time spent more efficient, preserves native
  species and habitats

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Conservation of Whales andOther Marine Mammals

• Its easier to save a species than to both
  harvest and save it
• Marine Mammal Protection Act Optimum sustainable
  population (OSP) rather than maximum sustainable
  yield

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• Two major categories of whales baleen and
  toothed

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• Drawings of whales date back to 2200 B.C.
• Whaling became pelagic whalers stayed
• at sea
• Whales provided many 19th-century products
• Decline is a global environmental issue
• International Whaling Commission (IWC)
• - Almost eliminated commercial whaling
• - Landmark in wildlife conservation

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Dolphins and Other Small Whales

• Many killed accidentally by other fishing efforts
• Groups are working together to solve problem
• - i.e. U.S. Marine Mammal Commission
• and commercial fishermen