stock size. Assume that the resource stock increases in size to P2.

The short run catch equation will shift upward to Cp2 resulting in a

catch of C3. With effort fixed at E2, the resulting catch is still

below sustainable yield and, hence, the resource stock once again

increases in size. This process will continue until the resource stock

reaches a level of Pe. At this resource stock size, the short run

catch function intersects the sustainable yield curve at E2 units of

effort implying that catch and sustainable yield are once again equal.

 If the initial change in effort were such that catch was greater

than sustainable yield, the short run catch functions would shift down

until catch and sustainable yield were equated at the new fixed level

of effort.