Presentation on theme: "Comments on Writing Awkward modifiers Example: By reading the clock, eleven thirty is the time. Improvement: By reading the clock, we can tell the."— Presentation transcript:
Comments on Writing Awkward modifiers Example: By reading the clock, eleven thirty is the time. Improvement: By reading the clock, we can tell the time is eleven thirty.
Comments on Writing Interrupting clauses Example: Please, if you haven't done so already, learn what an interrupting clause is and why, like me, readers are annoyed by it. Improvement: If you haven’t done so already, please learn about interrupting clauses. Readers are annoyed by them, including me.
Comments on Writing Non-sequiturs Example: The cat climbed the tree and therefore I like pizza. Improvement: The cat climbed the tree because it was scared. Not only, but also…. AND Example: The cat not only likes cheese but also crackers Improvement: The cat likes cheese and crackers
Comments on Writing Paragraph organization and topic sentences Lists There are three reasons why writing is important. First, writing helps you communicate ideas. Second, writing allows you to express yourself. Finally, when you know how to write, reading also becomes easier. Explanations If price goes up, quantity demanded will go down. If price goes up people will not be able to buy as much. They will also substitute away from the good and buy other goods, creating a decrease in the quantity demanded. Descriptions The data set is from 2010 covering households in Illinois. Each household answered 30 survey questions about their preferences regarding cats, pizza, and writing economic assignments. Participants received a $30 gift certificate for a completed survey.
Upcoming in Class Homework #8 due Wednesday Homework #9 due next Wednesday Quiz #4 Wednesday Nov. 13 th Group Outline due Wed. Nov. 13th
Chapter 13: Fisheries Fisheries: renewable resources with biological growth. Tragedy of the Commons associated with common pool resources (fisheries). Examine the difference between maximum sustainable yield and economic optimum. Examine the difference between the open- access outcome and the economic optimum.
Fish – Biological Dimension Our benefit from fish depends upon how fish stock grow over time. Milner Baily Schaefer developed a model that examines the relationship between fish stock and the growth of the fish stock. Schaefer worked as a biologist at the Washington State Fisheries Department in the 1930s and for the International Pacific Salmon Fisheries Commission in Canada in the 1940s. Most noted for his work on population dynamics of fisheries.
The Schaefer model Biological Dimension— The Schaefer model - an average relationship between the growth of the fish population and the size of the fish population. Small population sizes lead to population growth rate increases. Large population sizes lead to growth rate decreases.
Relationship between the Fish Population and Growth
Natural equilibrium – a population size that would persist in the absence of outside influences (Ŝ) Stable equilibrium – a population in which movements away from that level set forces in motion to restore it. (Ŝ) Minimum viable population – the lowest population below which growth in the population is negative (S) Sustainable catch or sustainable yield- a yield or harvest level that can be maintained without diminishing the resource stock or population Maximum sustainable yield population – the population size that yields the maximum growth. Definitions
What is the Static Efficient Sustainable Yield? Assumptions of the economic model are: The price of fish is constant and does not depend on the amount sold. (price-taker) The amount of fish caught per unit of effort expended is proportional to the size of the fish population. The marginal cost of a unit of fishing effort is constant. The static-efficient sustainable yield allocation maximizes the constant net benefit.
Open-access Problems Open-access fishing may or may not pose a threat of species extinction. Open-access resources do not automatically lead to a stock lower than the maximum sustainable yield. Open-access resources generally violate both the efficiency and sustainability criteria.
Problems with Open-access Resources Open-access creates two kinds of external costs: Contemporaneous external costs are the costs imposed on the current generation from overfishing. Too many resources (boats, fishermen, etc.) are committed to fishing. Intergenerational external costs are the costs imposed on the future generation from the exploitation of the stock today. Overfishing reduces stocks and thus future profits.