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