EXAMPLE 9 Cattle Ranching
We assume that the cost of raising and taking a steer to market is the same for every steer and does not depend on how many steers we take to market. What should our sustainable-yield harvesting policy be?
Because the cost does not depend on the population size, the cost curve is a horizontal line (Figure 23.13). As long as the selling price per unit is higher than the harvest cost per unit, we make a profit. The points of view of economics and biology agree, because the maximum profit occurs for the maximum sustainable yield.
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Figure 23.13: Figure 23.13 The unit cost, unit revenue, and unit profit of harvesting 1 unit, as a function of population size, for the cattle ranch.