# Basic Bioeconomics Model of Fishing

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Basic Bioeconomics Model of Fishing

Objectives of lecture Introduce you to basic bioeconomic analysis;
Introduce you to game theoretic applications to the study of shared fish stocks.

Catch per unit effort Catch per unit of fishing effort (CPUE) is the total catch divided by the total amount of effort used to harvest the catch. CPUE = c/E

Global catch and effort
Effort (GW or watts x 109) Catch (million tonnes) Year 5 10 15 20 25 30 40 50 60 70 80 90 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 Catch Effort is in Gigawatts (per year). Watt is a SI unit of power and is Joules per second. The solar constant includes all types of solar radiation, not just the visible light. It is measured by satellite to be roughly 1.366 kilowatts per square meter (kW/m²) which on average for the whole earth is 1.740×1017 W (or 1.74 x 108 GW or 174 Million GW) FAO Fisheries Statistics *Effective effort indexed on 2000 based on average 2.42% increase annually

Global catch and effort
Effort (GW or watts x 109) Catch (million tonnes) Year 5 10 15 20 25 30 40 50 60 70 80 90 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 Catch Effective effort* Effort is in Gigawatts (per year). Watt is a SI unit of power and is Joules per second. The solar constant includes all types of solar radiation, not just the visible light. It is measured by satellite to be roughly 1.366 kilowatts per square meter (kW/m²) which on average for the whole earth is 1.740×1017 W (or 1.74 x 108 GW or 174 Million GW) Watson et al. (2012) *Effective effort indexed on 2000 based on average 2.42% increase annually

Classical Management Problems
Overfishing; Overcapacity; Low or negative profits. Can you predict the above using only cpue and/or fishing mortality models? Nope! Bioeconomic models needed to predict these results!

These undesirable outcomes are the result of Individually Rational, but Non-cooperative Behavior

Issues in fisheries economics
Fish as natural capital in a broad sense; Fish as common property resource; Externalities  Tragedy of the commons   Private property; Need for regulation; Decision making over time.

Fish as natural capital in a broad sense
The natural environment contains the natural resources essential to life on earth; Natural resources provide inputs to our economic system; By and large economists see natural resources as similar to human made capital.

Economic efficiency and Bioeconomics

Economic efficiency Maximum profit subject to sustainability;
Profit = Total Revenue – Total Cost; With economic efficiency, profit is maximized.

A static single species model
Fisheries biology – the logistic model; The optimal harvest – equilibrium catch; The maximum sustainable yield; Sustainable yield as a function of effort; Max Profit= max(TR-TC):=Maximum Economic Yield; Profit=TR-TC=0:=Bionomic equilibrium.

The Basic Bioeconomic model
MEY MSY Bionomic equilibrium (BE) Total cost of fishing effort (TC) Total Revenue (TR) Fishing effort (E) TR & TC ( \$) E1 E2 E3 Max. rent Gordon Schaefer bioeconomic model

Bioeconomic Models (1) Biological Model: (2) Economic Model:
Net annual change of biomass = Growth + Recruitment – Nat. Mortality – Catch (2) Economic Model: Net annual revenue = Sales income - Cost

R = pH – cE Schaefer Catch Equation: H = qEx (Highly Dubious!) Therefore R = (pqx – c) E Bionomic Equilibrium: Under open access, fishery reduces the stock level x until R = 0, i.e., x = c/pq Predictions: Zero rents; overfishing ( if c/p low).

Numerical example: Bo = 1,000,000 t q = .001 / vessel yr c = \$ 500,000 / vessel yr Price p (\$/tonne) x (Bionomic Eq.) 500 1,000,000 t 1, ,000 t 5, ,000 t What is Bionomic Equilibrium?

How to Fix It? TACs? Gear Regulations? Limited Entry?
Vessel Buy-backs? Quasi-property rights through individualized (or community) quotas; MPAs; Taxes.

The objective of fisheries management:
Bioeconomic modeling The objective of fisheries management: Conservation of resources through time; Economic viability and profitability; Social objectives.

Economic rent/profit Total revenue = price*harvest (V).
Total cost = unit cost of effort* effort (C). Economic rent = V – C.

Dynamic bioeconomic model
Discounted economic rent (V-C) through time to obtain the discounted value of the economic benefits from the fishery.

Decision making over time
Natural resource (NR) use involves decision making over time: How much oil or gold should be extracted from a mine this year, how much next year, etc? Should salmon on the west coast of Canada be harvested intensively this year or not at all? Time is important because the supply curve of NRs are always shifting due to: Depletion of non-renewable resources and biological and physical changes in renewable resources.

Discount rate vs. discount factor; Present value vs. current value.
Hence, a dynamic rather than a static analysis is required to analyze natural resource use in most cases; Interest or discount rates are a crucial link between periods in dynamic models of NR use; Discount rate vs. discount factor; Present value vs. current value. Introduce your quiz!