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Water Use

Water Use. Fishing Techniques. Bottom Trawling Drift Nets Long Lines Purse Seine. Overfishing. Statistics 52% of fish stock fully exploited 16% overexploited 8% depleted Oceans viewed as unlimited resources Ocean productivity is low Light restricted to surface. Overfishing.

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Water Use

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  1. Water Use

  2. Fishing Techniques • Bottom Trawling • Drift Nets • Long Lines • Purse Seine

  3. Overfishing • Statistics • 52% of fish stock fully exploited • 16% overexploited • 8% depleted • Oceans viewed as unlimited resources • Ocean productivity is low • Light restricted to surface

  4. Overfishing • Supply 1% of food, represents 10% of protein • 1/3 of catch used for other purposes than food • Fish oil, fish meal, animal feed • 1/3 of global catch is bycatch • Discarded catch – sea turtles, marine mammals, shellfish

  5. Maximum Sustainable Yield • Highest rate of use that can be matched by replacement • Maximum that can be caught without causing population to crash • Generally occurs at ½ carrying capacity

  6. Maximum Sustainable Yield • How does it work? • How to determine it?

  7. Managing Fisheries • Regulate locations of fish farms and monitor pollution • Encourage production of herbivorous fish • Label products to indicated raised or caught by sustainable methods • Set catch limits below MSY • Prevent importation if not caught using sustainable methods • Increase marine sanctuaries and no-fishing areas • Monitor and destroy invasive species • Ban throwing back bycatch

  8. Restoring Habitats for Freshwater Fish

  9. Aquaculture • Commercial growing of aquatic organisms for food • Stocking, feeding, protecting, harvesting

  10. Aquaculture • Growing about 6% annually • Provides 5% of total food production • Most common products – seaweeds, mussels, oysters, shrimp, certain fish (salmon, trout, catfish)

  11. Aquaculture • Problems

  12. International Whaling • Heavily depleted until 1980s • 1974 International Whaling Commission (IWC) • 1986 IWC enacted moratorium on all whaling

  13. Coral Reef

  14. Coral Reefs • Most diverse and biologically productive ecosystems • Corals (animal) have a mutualistic relationship with photosynthetic algae (zooxanthellae) • Generate $375 billion in tourism and fishing revenue

  15. Coral Reefs • Bleaching • Exploitation

  16. Mangroves • Often located inland of coral reefs • Trees have ability to root and grow in shallow marine sediments

  17. Mangroves • Services

  18. Mangroves • Damage • Coastal development • Logging • Shrimp aquaculture • Mangrove is cleared • Land bulldozed to make shallow ponds • Black tiger prawns grown in ponds ($multibillion industry) • Pond becomes polluted  shrimp no longer grow  new ponds created, old ponds are flushed and pollution damages adjacent coastal environments

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