The walleye pollock fishery is the largest single species fishery in the world. In the United States alone, fishermen landed 3.3 billion pounds in 2002. Most of the pollock is taken by large trawlers and processed into frozen products, surimi, and roe. Walleye pollock range from the Bering Sea and Gulf of Alaska south to the Japanese archipelago in the west and the coast of northern California in the east. They are schooling mid-water and bottom-dwelling fish that live in depths from near shore shallows to 3,000 feet, but most are found between 300 and 900 feet. The U.S. fishery is managed under a system of quotas owned by fishermen and processors, with shares also going to native Alaskan co-ops on the Bering Sea and Gulf of Alaska coasts. During spawning, large numbers of pollock gather near shore and each female over three years of age produces about a half million free-floating planktonic eggs. An average of two and a half individuals will survive to sexual maturity.