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Chapter 3.2 Forests and Fisheries
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Pre-Chapter Activity What happened to the Tuna?
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Forest Resources Forest provides many valuable resources: -maple syrup -rubber -nuts -wood pulp for making paper -construction and paper -furniture -oxygen for people -prevent flooding and control soil erosion
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What are some of the things made from trees in this classroom? Writing paper Cardboard Poster board Toilet paper Textbooks Furniture Pencils
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Managing Forests There are 300 million hectares of forest in USA. 1 million of people work for the forest industry Because new trees can be planted or replaced trees that are cut down, forests can be renewable resources.
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Logging Methods 2 methods of logging: 1. Clear cutting 2. Selective cutting
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1. Clear-cutting method Cutting down all the trees in an area at once. Advantages: faster and cheaper; safer for loggers Disadvantages: more damages to forests; ecosystem changes, the soil is exposed to wind and rain, and can be blown away or washed away.
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Clear-cut forest
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2. Selective cutting method Is cutting some trees in a forest and leaving a mix of tree sizes and species behind. Advantages: less damaging to forest Disadvantages: loggers must move their heavy equipment around the forest
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Selective cut forest
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Sustainable forestry Forests should provide a sustainable yield which is an amount of renewable resource such as trees that can be harvested regularly without reducing the future supply. # Cut trees = # of planted trees
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Certified Wood The Forest Stewardship Council is an international organization dedicated to sustainable forest management. The certify forests that are well managed and provide good working conditions for workers.
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Fisheries Is an area with a large population of marine organisms. They are valuable renewable resources. In the past, there were so many fish to catch. Over time, the population of fish declined. WHY???
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WHY??? What happened? The fish were caught faster than they could breed, so the population decreased. This is called “overfishing.”
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Managing fisheries for a sustainable yield includes: 1. Setting fishing limits 2. Changing fishing methods 3. Developing aquaculture techniques 4. Finding new resources
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1. Fishing Limits Laws can ban fishing of certain species. Laws can limit the number or size of fish or require that fish be in a specific size range. Laws want to make sure that fish survive long enough to reproduce and that not all of the largest adult fish aren’t caught.
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2. Fishing Methods Today many fishermen catch fish with nets with a larger mesh size that allow small young fish to escape. Some fishing method are controlled by laws. Some of them are old; like the one that allows poison fish with cyanide and stunning them with dynamite under water. These methods hurt all the fish in an area rather than targeting certain fish.
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3. Aquaculture Is a practice of raising fish for food in artificial ponds or bays (ex. salmon, catfish, shrimp) Disadvantages: replace natural habitats; cause pollution and spread diseases into wild fish population
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4. New Resources -9,000 different fish species are caught for food -one way is to help feed a growing human population is to fish for a new species such as monkfish, tile fish and tilapia.
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Questions: Why is forests important?
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What is a sustainable yield?
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What is aquaculture?
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How can setting limits on the size of fish that can be caught help maintain fish populations?
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What steps do you think scientists might take to convince the public to eat different species of fish?
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Ch 2.3 Assessment 1a. Why are forests considered renewable resource? 1b. How does the clear-cutting logging method differ from selective cutting? 1c. You are walking in a clear-cut section of forest a few days after a heavy rainstorm. A nearby stream is very muddy and has many dead fish. What might have happened?
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Ch 3.2 Assessment (con’t.) 2a. What are four ways fisheries can be managed for a sustainable yield? 2b. What are two kinds of laws that regulate fishing? How can they help ensure the health of a fishery? 2c. What might happen to a fish population over time if all the largest fish in the population were caught? Explain.
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