marine - Lecture10 ManyNames,OneOcean...

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Lecture 10
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Many Names, One Ocean 52% 20% 25% % of water in each basin (Atlantic/Arctic combined)
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Significant variations between different areas Shallow basins with limited connection often quite different
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Ocean as global sink Oceans are “base level” – a global sink that  everything flows to § Gases –  ex. carbon dioxide § Liquids – runoff returns water (and pollutants) § Solids – deposited by  wind and water
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Biologically and Ecological Significant Marine  Variables Regional water temps  – dissolved oxygen levels, cold water  has more oxygen Regional salinity  – high where inflow is low and evaporation  is high Upwellings  – cold nutrient rich water moving to surface,  continental margins Sunlight in the euphotic (illuminated) zone  – 20 meters
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Ocean-Land Interface Estuaries –  where freshwater rivers meet the ocean Estuaries and associated saltmarshes § Important spawning sites § Account of for 99% of all  fish production Nearshore water most  productive near upwellings
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Global Fishing Zones 99% of fish catches are in upwelling zones or coastal zones.
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Trajectory of Global Fish Harvesting (1950-2002)
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Areas of  Concern  for Overfishing Serious declines  are evident in  many areas These graphs  show catch rate –  a measure of effort  it takes to catch  fish
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Purse Seine Fishing
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Decline in Northeastern US Fish Harvests (1982-1996
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Collapse of the Northeastern Cod Fishery
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North Atlantic Cod Cod Catch Cod Biomass
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Industrialization of Cod Fishing Traditional  Industrial   Gillnet  Trawler
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Collapse of the Pacific Sardine Catch
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Reduction in Northwest  Atlantic Large Fish Biomass,  1900-1999 (in metric tons per km sq) 1900 1950 1975 1999 Examples of “large fish” are cod, halibut and tuna
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Reduction in Shark Species, 1986-2000
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By-catch Unintended animals caught while fishing for 
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This note was uploaded on 10/16/2011 for the course GEOGRAPHY 211 taught by Professor Smith during the Spring '11 term at Rutgers.

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marine - Lecture10 ManyNames,OneOcean...

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