Geog 5 Week 3 Lecture 4 01 24 2012 Chapter 11 Oceans and Fisheries Fisheries wherever a large amt of fish are farmed caught also wild fisheries not just farm fisheries What are the challenges with fisheries Fish is 90 of the diet on islands Challenges Overuse all fish are removed from an area Imbalance from overfishing one species like tuna 75 of fish stocks are exploited or depleted By catch the capturing of sea life that you don t want dolphins etc Degredation Tragedy of the Commons common resource that everyone is utilizing Species have been harvested far past their limit cannot grow as big or as many as before Earth s Oceans 75 of Earth s surface is made up of water Why Because we are exactly the appropriate distance from the sun to have three types of water liquid ice gas 4 main oceans but really just one big ocean Arctic Pacific Atlantic Indian Global Ocean Circulation Gyres large ocean currents Largest North South Atlantic North South Pacific Indian North goes clockwise South goes counterclockwise Corioles Effect understanding the direction Rubber Ducky Armada Many cargo things go overboard into the ocean 1992 2004 the bath toys were floating around the ocean and were recovered over those years 2007 the rest of the bath toys were recovered in England The Global Conveyor Belt a k a Thermohaline Cold salty water is denser than warm less salty water because salt is dense therefore there s more mass Cold salty water going to sink to the bottom of the deepest current Warm less salty water shallow current Affects the climate around the world particularly Tropics and polar regions ex Europe was warmer than normal a few years ago Ocean and Atmosphere Interaction El Nino occurs every five years roughly Gulf of Mexico Texas drought Creates hurricanes and only in warm water roughly 80 degree water Dramatically affects weather lots of changes very difficult on the human population Western Pacific drought ex Australia Eastern Pacific lots of rain ex U S 1997 98 worst in history higher air pressure warmer water La Nina opposite effect on weather than El Nino lower air pressure colder water o Follows immediately after El Nino 01 24 2012 01 24 2012