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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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Fishing techniques
Fishing Techniques

  • Bottom Trawling

  • Drift Nets

  • Long Lines

  • Purse Seine


Overfishing
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


Overfishing1
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


Maximum sustainable yield
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


Maximum sustainable yield1
Maximum Sustainable Yield

  • How does it work?

  • How to determine it?


Managing fisheries
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



Aquaculture
Aquaculture

  • Commercial growing of aquatic organisms for food

    • Stocking, feeding, protecting, harvesting


Aquaculture1
Aquaculture

  • Growing about 6% annually

  • Provides 5% of total food production

  • Most common products – seaweeds, mussels, oysters, shrimp, certain fish (salmon, trout, catfish)


Aquaculture2
Aquaculture

  • Problems


International whaling
International Whaling

  • Heavily depleted until 1980s

  • 1974 International Whaling Commission (IWC)

  • 1986 IWC enacted moratorium on all whaling



Coral reefs
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


Coral reefs1
Coral Reefs

  • Bleaching

  • Exploitation


Mangroves
Mangroves

  • Often located inland of coral reefs

  • Trees have ability to root and grow in shallow marine sediments


Mangroves1
Mangroves

  • Services


Mangroves2
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