Bioeconomic Model Flashcards
Population change =
Recruitment + individual growth - natural mortality - fishing mortality
Compensatory growth
Rate of popn growth over time declines at higher population densities (slow growth rate at higher densities)
-r(X(sub)t) decreasing function of (X(sub)t)
-everywhere on graph is concave
Depensatory growth
Rate of popn growth increases at higher popn densities
-r(X(sub)t) increasing function of (X(sub)t)
-on graph: at lower F(x)=convex, higher F(x)=concave
Allee affect
Growth rate is dependant on population density, with lower growth rates at lower population sizes
Allee threshold/ minimum viable population
Below this threshold, a population will irreversibly go to extinction
-an unstable equilibrium
Environmental carrying capacity
Maximum population size that environment can indefinitely sustain
-if population is here, it is an unexploited population
Critical level of effort
Effort under which fish stock reaches k(sub)0, which means the population will go to extinction
Overfishing
Level of fishing that jeopardizes the capacity to produce MSY on a continuing basis
Overfished
The stock has been depleted below the level it can replenish itself naturally.
How to go from Yield Effort Curve to Total Revenue Curve
Multiply yield by price
Bionomic equilibrium inefficiencies
- Economic = fishery could have economic rent, but does not, overcapacity, overcapitalization, too many vessels chasing too few fish
- Biological = overfished resource stock when X < X(MSY)
Bionomic equilibrium tragedy of the commons
Cost of effort is covered, but no economic rent left over to pay for unpriced resource stock. This leads to resource stock being reduced below optimum level. = technological resource stock externality
How to get Marginal Revenue from Total Revenue curve
Slope of tangent line at total revenue curve
How to get average revenue from total revenue curve
Total Revenue ÷ quantity sold
Total Revenue
Yield × price
Marginal Revenue
Slope of tangent line
Average revenue
Total revenue ÷ quantity
Total cost
c × E
(c= constant cost per unit effort)
-This includes opportunity cost
