The classic example of omitting environmental variability in fisheries management strategies is the Peruvian anchovy industry, which had an estimated MSY of 9 to 10 million tons per year from 1964 through 1971. The Peruvian anchovy (Engraulis ringens) was the world's largest marine fishery—until its sudden collapse in 1972. The problem was that fishery managers had overlooked the impact of El Niño (Chapter 8: Breathing Planet), which is a periodic global ocean-atmosphere event that reduces the upwelling supply of nutrients for the phytoplank-ton prey of the anchovy along the Pacific Ocean coast of South America. As a consequence of the impacts from El Nino, anchovy recruitment rates were reduced more than 85%. Unfortunately, because MSY remained the same without compensating for the El Nino impact, the Peruvian anchovy population was dramatically overharvested.
Fisheries generate value in proportion to the balance between yield and effort (Fig. 10.9). When populations are large with many big individuals, it is relatively easy and inexpensive to generate large catch sizes. As populations are depleted, leaving smaller individuals with a lower yield per recruit, more effort (i.e., greater cost) is required to maintain a uniform catch size. In both cases, the greatest return on investment (difference between the cost and yield value) for a fishery exists at levels of effort that are below the MSY.
These economic and ecological aspects of living resource activities share the ''eco-'' root associated with the ''household'' that is managed and studied, respectively. A key feature of household management is considering the ability to acquire necessary resources, commodities, or services. Access to goods is influenced by supply and demand features, which determines their costs (Fig. 10.12), as classically recognized by Alfred Marshall (1842-1924).
FIGURE 10.12 Prices and quantities of a marketable good or service in relation to consumer demands and producer supplies. The equilibrium market price represents the balance between supplies and demands, with higher prices leading to surpluses and lower prices leading to shortages of the good or service.
FIGURE 10.13 Managing natural resources, ecosystems, and environments in the Earth system requires scientific, economic, government, and societal information. Information itself embodies a dynamic process of iterative acquisition, assessment, and utilization of basic and applied data (Fig. IV) for the welfare of all stakeholders. Modified from the Earth System Sciences Committee (1988).
to buy at a given price based on their incomes, available alternatives, and personal tastes. Alternatively, supplies of a good relate to available quantities that a producer is willing and able to sell at a given price based on production costs, unexpected events, and competition. Equilibrium between consumer demands and producer supplies sets the market price (Fig. 10.12). Prices above the market price create surpluses; prices below the market price create shortages. As a consequence, excess supplies will force prices down, whereas excess demands drive price up, adjusting toward the equilibrium market price.