Consider a simple economy whose only industry is fishing. in this industry, productivity—the amount of goods and services a worker can produce per hour—is measured by the number of fish one fisherman catches per hour.
i think i is not right to base the productivity of the fisherman in per hour basis because fisherman goes to the sea and catch fish not on a daily basis. maybe the correct way to express it is per trip they go to the sea. because if it hourly basis then the productivity is very small.