Consider a ?sh stock with growth function g(St?Ht), where St is the stock size at the beginning of period t and Ht is harvest.

We have shown that the optimal catch quantity in period 1 is characterized by the condition

where p > 0 is the ?sh price, c > 0 is a parameter of the cost function and ? > 0 is the discount factor.

a) Give a de?nition of the term over?shing. b) Give an economic interpretation of condition (1) c) Why does open access lead to over?shing? d) What would be an appropriate regulation to avoid over?shing?

P C S - H + -8 (p- & ) ( (1 + g'(S - H)), (1)