Fish farming, or the growing of edible fish in small freshwater ponds and sea inlets blocked with earthen dams, began in China thousands of years ago. Twenty years ago, Chinese fish farmers were producing about a million tons of fish each year. Since then, production of farmed fish has increased dramatically. Chinese fish farmers currently produce almost 35 million tons of fish per year, or more than 70 percent of the world’s total production of farmed fish. Much of this yield goes for human consumption in China and other Asian nations, where Chinese fish farmers now sell a considerable amount of their fish production. The rest of China’s farmed fish is used to produce fish meal and fish oil. These fish by-products are fed to poultry and pigs and to carnivorous fish such as salmon, eel, and cod grown in fish farms.

Back in the 1980s, environmentalists worried that wild fish populations in the world’s oceans, lakes, and rivers would eventually be extinguished as the global human population increased. In fact, annual catches of wild fish have been declining since the 1990s. The reason is that consumers in Asia and elsewhere have gradually been substituting farmed fish for wild fish. Current estimates indicate that by 2030 more than half of the fish consumed globally will be grown on farms.

What do you suppose has happened to the market price of wild fish such as salmon and shrimp since the 1980s as the farmed fish share of U.S. fish consumption has risen from less than 10 percent to more than 50 percent?