Walleye pollock is well known as valuable commercial fishes, an important forage fish for marine fish and wildlife and as a dominant marine competitor and predator. The importance of the commercial fishery for walleye pollock is highlighted by the six million ton catch in 1985 worth over $1 billion in ex-vessel income, which made it the world’s largest single-species fishery. However, the pollock's economic importance may be overshadowed by its ecological importance. Pollock dominates the pelagic fish biomass in the Bering Sea and the Gulf of Alaska. Pollock, along with Pacific herring are the two most abundant fish species in Prince William Sound. Over the last two decades, pollock abundance in Prince William Sound has ranged from 20 to 50 thousand tons.

PWSSC began monitoring the abundance of pollock in 1995 after fishers observed large concentrations of pollock on their depth sounders. The estimate from that first survey, 38,000 tons, led to a commercial fishery on the pollock in PWS. Subsequently, research on pollock by PWSSC has been driven by concerns over the relationship between pollock and Steller sea lions. The commercial fishery for pollock in Alaska was implicated in the decline to the Steller sea lions and subsequent listing of the sea lions as endangered. However, the research by PWSSC suggested that declines in herring were the more likely factor in the decline .

Pollock is a major predator on pink salmon fry and other juvenile fishes. Research by PWSSC and other investigators has shown that pink salmon survival is strongly affected by pollock predation. The predation by pollock is also affected by zooplankton abundance. When zooplankton abundance is high, pollock feed primarily on the zooplankton. But when zooplankton abundance is low, pollock look for alternate food sources, which include pink salmon fry. Pollock may also be a major predator on juvenile herring and may be a factor in the failure of the herring population in Prince William Sound to recover following the Exxon Valdez Oil Spill. Pollock and herring, as the two major pelagic fish species in Prince William Sound, are competitors for food in the ecosystem. Evidence suggests that herring and pollock change relative dominance in the Gulf of Alaska, similar to the situation with anchovy and sardines off Southern California (Pollock Fig 1).