The culture of marine organisms may be classified into four categories. Marine animal husbandry: the intensive culture in floating pens or impoundments of salmonids in Europe and North America and yellowtail (Seriola quinqueradiata), puffer, and shrimp (Penaeus japonicus) in Japan yields 3,000–610,000 kg/ha per yr. Traditional mariculture: the culture of milkfish, mullet and shrimp in ponds and ground culture of oysters and mussels yields 200–5,000 kg/ha per yr. Float culture of sessiles such as oysters, mussels, and algae yields 80,000–750,000 kg/ha per yr. Sea ranching: the culture of salmonids in hatcheries, release prior to migration and subsequent recapture. Coho (Oncorhynchus kisutch), chinook (O. tshawytscha), and Atlantic salmon (Salmo salar) yield 0.76–2.5 million kg/ha per yr while pink (O. gorbuscha) and chum salmon (O. keta) yield 2.3–22.0 million kg/ha per yr. Data on nutritional and ecological requirements are discussed in relation to the feasibility of increasing yields using genetic methods.