Though cattle and poultry have been domesticated for centuries, awareness of farmed seafood is relatively recent for most Americans. But domestication is becoming increasingly important as natural fish habitats around the globe are depleted and world population increases. Aquaculture, like agriculture, is farming, but in water instead of on land. It can take place in natural environments, such as rivers or lakes, or artificial ones, such as the inland ponds created to raise catfish and tilapia. Oysters, mussels, clams, shrimp, salmon and other species are raised in salt water. Like most other ocean fish, farmed salmon-primarily the Atlantic species-are bred in floating pens off the shores of North and South America and Northern Europe.