Human impacts on Aquatic Biodiversity

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Human impacts on Aquatic Biodiversity

• Our large aquatic footprint

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Greatest Threat Habitat Degradation

• During the last century weve lost or damaged
• ½ of the worlds coastal wetlands
• ¼ of the worlds coral reefs (another 70 by
  2050)
• 1/3 of the worlds mangrove forest swamps
• Many bottom habitats due to dredging and trawler
  fishing

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Gone FishingFish Gone

• Overfishing taking so many fish too few left
  to maintain population
• Todays fishing methods use
• Sonar
• GPS
• Aircrafts
• to find fish

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Types of fishing

• Trawler drag net on/near ocean floor
• Weighed down
• clear cuts everything on
• ocean floor
• Nets so big some could
• swallow 12 jumbo jets

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• LOTS of bycatch non-target species
  accidentally caught.
• Thrown back dead or dying

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• T.E.D Turtle Exclusion Device a grid of bars
  with an opening at top/bottom of net small
  animals pass through large ones strike bars and
  are ejected.

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• 2. Purse-Seine surround school of fish with net
  and close net like a drawstring
• More bycatch!!

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• 3. Long-lining put out lines up to 80 miles long
  with thousands of baited hooks

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Even more bycatch!
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• Reduce bycatch with longlining Switch bait!
• use of mackerel instead of squid

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• 4. Drift-net fishing transparent nets (up to 40
  miles long and 50 feet deep) hang below surface,
  marine life becomes ensnared

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Bycatch!
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Alternatives?Fish farming - Aquaculture
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advantages

• Efficient
• High yield
• Higher yield through cross breeding and genetic
  engineering
• Reduce overharvesting of conventional (wild)
  fisheries
• Little use of fuel profits not tied to price of
  oil
• High profits

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disadvantages

• Large inputs of land, feed, and, water needed
• Produces large and concentrated outputs of waste
• Increased grain production needed to feed some
  species
• Increased catch of other fish as food source
• Fish susceptible to pesticide run-off
• Dense populations susceptible to disease
• Escaped farmed fish can infect wild populations
  (disease, parasites, and genetics) this is a
  recent headline
• 40,000 Atlantic Salmon Escape Canadian Fish
  Farm Into the Pacific
• Tanks/ponds/mangrove swamps too contaminated in a
  few short years (example shrimp in the Mangrove
  swamps)

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• Total world fisheries collapse by 2048??

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ITQs

• A TAC (total allowable catch) is set which is
  species specific
• Shares of the TAC are allocated to fishing
  vessel owners
• The owners can take their fish quota or they can
  buy or sell shares from other owners.

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• Difficult to enforce!
• TAC cant be set too high!!

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Exclusive Economic Zones