Question

why is there a difference between the maximum sustained yield and the economically efficient sustained yield.

Answer 1

Maximum sustained yield is based on assumption that you put in all effort. Hence, there is no consideration of costs and labor in this process. Economically efficient sustained yield ensures that the effort is less, however, permanent stock level is higher. The maximum sustained yield is not socially welfare in terms of economics.

Lets take an example where a company forces its employees to work for 18 hours. now, it will have high output, compared to a company where workers work for 8 hours. However, because of the long hours, workers would start getting tired and feel less compensated.