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Overfishing2 Overfishing2 Presentation Transcript

  • Overfishing By Sofia Marcheva Ivaylo Nikolov
  • Overfishing (13)
    • Catching too much fish for the system to support
    • Overfishing is a non-sustainable use of the oceans
    • 3 types:
      • Growth – harvesting fish before it reaches a reasonable size to produce the max. yield
      • Recruit – not enough adults to reproduce
      • Ecosystem – when overfishing changes the ecosystem (decrease in predatory species  increase in small fishes)
  • Level of Global Fish Catch (15)
    • 2006 – 144 million tonnes (capture fisheries + aquaculture)
      • 110 millions – for human consumption
    • China and Peru – largest fish catch
    • More than ½ of monitored fish stocks – fully exploited
    • About ¼ are overexploited or slowly recovering
    • Maximum potential of world’s capture fisheries is reached  measures need to be taken
    • Scientists are concerned about the sustainability of fish catches and remind that actions need to be taken ASAP
  • Fishing down the food chain
    • Hunting fishes down the trophic levels in the food web (11)
    • Decline in Mean trophic level (14)
    • Transition from high trophic level, big-sized fish to small low trophic level species that live shorter (14)
    • Results at first in increase in fish catch, but then it declines (14)
    • Fishermen tend to catch larger fishes, but then they become less and there is a shift to smaller fishes (11)
    • Shows unsustainability (11)
  • Bycatch
    • Fish caught unintentionally while hunting other species(3)
    • Sometimes bycatch is kept or sold(4)
    • Ex. Catching bluefish while fishing striped bass( костур)
    • Throwing back the bycatch is called discard.(4)
    • Discarding can lead to change of current population of a specie(4)
  • Damaging fishing methods
    • Cyanide fishing- cheap and effective(9)
    • Explosive fishing- using explosives to kill the fish. Major cause of reef destruction
    • Longline fishing-lined up
    • baited hooks. Estimated to
    • Kill 180 000 birds worldwide(7)
    • Trawls- nets that catch the
    • fish by force(9)
    http://static.howstuffworks.com/gif/coral-reef-blasting.jpg
  • Bottom-trawling
    • Throwing a net on the sea floor by ship(2)
    • The net is being dragged by the ship(2)
    • Beam and otter trawling(2)
    • Destroys reefs and sea bottom(8)
    • http://www.youtube.com/watch?v=zikSzUhUGtA
    http:// upload.wikimedia.org/wikipedia/en/6/6f/Benthictrawl.jpg
  • No-take zones
    • Preserved areas where species are protected(8)
    • Some no-take zones are police secured and difficult to enter(8)
    • They create environment for restoring ecosystems and increase of population(8)
  • Aquaculture (Impact on Wild Species) (1)
    • Aquafarming (cultivating most needed species and keeping them under controlled conditions) vs. commercial fishing (harvesting of wild species)
    • Negative impact on wild species
    • Ex. Salmon – affects wild salmon and forage fish
      • Great demand for salmon  even greater for forage fish to feed them  problem for wild salmon
  • Cod in Newfoundland
    • Cod population was extremely plentiful(5)
    • In 1990 the interest in cod grew larger and the result was overfishing(5)
    • Fisherman started using small ships that returned to shore every day(5)
    • John Cabot found the cod
    • schools and made them
    • popular(6)
    http://www.dhushara.com/book/diversit/extra/cod/cod.htm
    • In 1951 the factories started producing super-trawlers like 'Fairtry' which had vast capacity(5)
    • In 1968 was the peak of catch cod-810000(5)
    • More than 3 times larger before the super-trawlers(5)
    • 1990s - industry crash(5)
    • Result- complete extinction
    • of cod in those regions(5)
    http://www.grantontrawlers.com/Trawlers%20Images/Fairtry-1-LH-8an.jpg http://www.dhushara.com/book/diversit/extra/cod/cod.htm
  • Bluefin Tuna
    • Large migratory fish – Atlantic + Mediterranean (17)
    • 4m, 250kg, >70km/h (17)
    • Faces extinction (17)
    • Actual amount of tuna caught – uncertain (16)
    • 2008, 2009 – UN decreased the tuna season claiming that quotas have been early reached (16)
    • Japan – 90% of bluefin tuna caught in the Mediterranean (16)
  • Bluefin Tuna
    • 2010 – global ban on the trade of Bluefin Tuna – unsuccessful (16)
    • Great arguments whether the catch will be sustainable in the future (16)
    • http://images.suite101.com/1686405_com_bluefintun.jpeg http://www.nyu.edu/projects/aphrodisias/index2.html
  • Works Cited
    • &quot;Aquaculture.&quot; Wikipedia . Web. 15 June 2010. <http://en.wikipedia.org/wiki/Aquaculture#Impacts_on_wild_fish>.
    • &quot;Bottom Trawling.&quot; Wikipedia, the Free Encyclopedia. 8 June 2010. Web. 15 June 2010. <http://en.wikipedia.org/wiki/Bottom_trawling>.
    • &quot;Bycatch.&quot; Wikipedia, the Free Encyclopedia. 6 June 2010. Web. 15 June 2010. <http://en.wikipedia.org/wiki/Bycatch>
    • Castro, Kathleen. &quot;Bycatch.&quot; Rhode Island Sea Grant. Web. 15 June 2010. <http://seagrant.gso.uri.edu/factsheets/Bycatch.html>.
    • Century, The 19th. &quot;Cod Fishing in Newfoundland.&quot; Wikipedia, the Free Encyclopedia. 20 Apr. 2010. Web. 15 June 2010.<http://en.wikipedia.org/wiki/Cod_fishing_in_Newfoundland>.
    • &quot;Cod Gone.&quot; Dhushara. Web. 15 June 2010. <http://www.dhushara.com/book/diversit/extra/cod/cod.htm>.
    • &quot;Coral Degradation through Destructive Fishing Practices.&quot; Encyclopedia of Earth. 24 Aug. 2008. Web. 15 June 2010.<http://www.eoearth.org/article/Coral_degradation_through_destructive_fishing_practices#Explosive_Fishing>
    • &quot;Coral Reefs Doomed, Study Says; Centuries of Overfishing Killing Ecosystems.&quot; Common Dreams | News & Views. 2003. Web. 15 June 2010.<http://www.commondreams.org/headlines03/0816-06.htm>.
    • Destructive Fishing.&quot; CopperWiki. 8 Mar. 2010. Web. 15 June 2010. <http://www.copperwiki.org/index.php/Destructive_fishing>
    • &quot;FISHING DOWN THE FOOD CHAIN.&quot; Site Has Moved. Web. 15 June 2010. <http://archive.greenpeace.org/comms/fish/part3.html>.
    • &quot;Fishing down the Food Web.&quot; Wikipedia . Web. 15 June 2010. <http://en.wikipedia.org/wiki/Fishing_down_the_food_web>.
    • &quot;Overfishing - A Global Environmental Problem, Threat and Disaster.&quot; Overfishing - A Global Environmental Problem, Threat and Disaster. Web. 15 June 2010. http://overfishing.org/pages/why_is_overfishing_a_problem.php
    • &quot;Overfishing.&quot; Wikipedia . Web. 15 June 2010. <http://en.wikipedia.org/wiki/Overfishing>.
    • Pauly, Daniel. &quot;Fishing Down Marine Food Webs.&quot; Science/AAAS . 6 Feb. 1998. Web. 15 June 2010. <http://sciencemag.org/cgi/content/short/279/5352/860>.
    • &quot;Scientific Facts on Fisheries Latest Data.&quot; GreenFacts . Web. 15 June 2010. <http://www.greenfacts.org/en/fisheries/index.htm>.
    • Somerfield, Mark. &quot;Bluefin Tuna Fishing in the Mediterranean.&quot; European Affairs . 21 Mar. 2010. Web. 15 June 2010. <http://eeuropeanrussianaffairs.suite101.com/article.cfm/bluefin-tuna-fishing-in-the-mediterranean>.
    • &quot;WWF - Bluefin Tuna in Crisis.&quot; WWF . Web. 15 June 2010. <http://wwf.panda.org/what_we_do/footprint/smart_fishing/sustainable_fisheries/bluefin_tuna/>.