1. Growth rate (replacement) and size of the fish stock/pool
Too Small/Low Stock Size
Lower growth rate as fish can’t hook up and reproduce
Birth (replacement) less than death/harvest
Growth rate declines; species becomes extinct
Too Large Stock Size
Food sources (plankton, biomass, other fish) too small to support large # of fish
Growth rate declines

2. Schaffer model: Relationship between the Fish Population and Growth

3. 3 Possible Solutions 1. Open (unregulated) Fisheries (Ec)
Catch until total costs exceed revenues (up to zero profits) => ATC(Q) = TotRev(Q) = P*Q
2. Maximum Sustainable Yield(MSY) (Em)
Largest “harvest” that can be sustained every year (harvest = replacement rate)
Biologist solution
3. Economically Efficient (Eo)
Maximize Economic Value MC(Q) = MR(Q)

4. FIGURE 14.2 Efficient Sustainable Yield for a Fishery