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Pg. 114 RTW: What is one problem caused by invasive species? Objective: I will be able to describe methods of commercial fishing and their impact on the world’s oceans. Agenda: Gallery Walk Invasive Species (pg. 114) Homework: Study for Invasive/Overfishing Quiz on Friday Monday, February 23 rd, 2015
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Pg. 114 RTW: Should we kill invasive species? Objective: I will be able to describe methods of commercial fishing and their impact on the world’s oceans. Agenda: Tragedy of the Commons Lab Homework: Study for Invasive/Overfishing Quiz on Friday Tuesday, February 24 th, 2015
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Pg. 114 RTW: What is the tragedy of the commons? Give an example of a public/global common Objective: I will be able to describe methods of commercial fishing and their impact on the world’s oceans. Agenda: Overfishing notes pg. 115 Homework: Study for Invasive/Overfishing Quiz on Friday Wednesday, February 25 th, 2015
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Overfishing
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Cod Tuna Sharks Grouper Swordfish Some of the Most Exploited Fish Stocks:
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= the maximum level at which a natural resource can be routinely exploited without long-term depletion. Currently we are exploiting our fish stocks to such an extent that experts expect that the fishing industry will collapse by 2050! Maximum Sustainable Yield
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The Consequences
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Pg. 114 RTW: List the most threatened fish stocks. Objective: I will be able to explain the concept of overfishing in terms of maximum sustainable yield and cite examples of overfished stocks. Agenda: Overfishing Notes (pg. 115) Homework: Study for Invasive/Overfishing Quiz on Friday Thursday, February 26 th, 2015
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Gill nets Purse seine nets Trawling Long lines Drift nets Different Fishing Methods
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Gill Nets
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Gill nets are vertical panels of netting normally set in a straight line. Fish may be caught by gill nets in 3 ways : 1. wedged – held by the mesh around the body 2.gilled – held by mesh slipping behind the opercula 3.tangled – held by teeth, spines, maxillaries, or other protrusions without the body penetrating the mesh. Mesh size, twine strength, as well as net length and depth are all closely regulated to reduce bycatch of non-target species. Gill Nets
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Purse Seine Nets
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A purse seine is a large wall of netting deployed around an entire area or school of fish. The seine has floats along the top line with a lead line threaded through rings along the bottom. Once a school of fish is located, a skiff encircles the school with the net. The lead line is then pulled in, "pursing" the net closed on the bottom, preventing fish from escaping by swimming downward. Purse Seine Nets
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Trawling
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Trawls are nets towed behind a boat to collect organisms. Trawls can be divided into three categories based on where they sample the water column: 1.Surface 2.Midwater 3.Bottom Trawling
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Long Lines
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Long lines use a long line, called the main line, with baited hooks attached at intervals by means of branch lines called snoods. Longlines can be set to hang near the surface (pelagic longline) or along the sea floor (demersal longline)
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Long Lines Long lines use a long line, called the main line, with baited hooks attached at intervals by means of branch lines called snoods. Longlines can be set to hang near the surface (pelagic longline) or along the sea floor (demersal longline)
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Drift Nets
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Drift nets hang vertically in the water column without being anchored to the bottom. The main difference between gill nets and drift nets is whether or not they are anchored to the bottom. Drift Nets
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Drift Nets vs Gill Nets
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Bycatch= the unwanted fish and other marine creatures caught during commercial fishing for a different species. Trawling methods can damage coral reefs and other ecosystems Unsustainable Problems with Fishing Methods
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Solutions? Reduce bycatch with alternative gear (turtle exclusion hatch or circle hooks) Use sustainable methods
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Buoy Caught Swordfish Buoy Caught Swordfish Sustainable Fish Sustainable Fish Need for Sustainable Fishing Need for Sustainable Fishing
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Pg. 114 RTW: Name one type of fishing method and how it negatively impacts the oceans. Objective: I will be able to explain the concept of overfishing in terms of maximum sustainable yield and cite examples of overfished stocks. Agenda: Quiz on Invasive Species/Overfishing Shark Finning Homework: None Friday, February 27 th, 2015
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Shark Finning
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What if There Were No Sharks What if There Were No Sharks Shark Fin CSI Shark Fin CSI Shark Finning Shark Finning
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