Among Alaska's sockeye salmon fisheries, few reward fishermen as handsomely as the Copper River sockeye salmon fishery. Copper River king and sockeye command top-dollar in the market. And Copper River sockeye arrive much earlier than other Alaska sockeye runs. Copper River sockeye begin to arrive in mid to late May, providing the state's first fresh sockeye of the year. In addition to king and sockeye salmon, the Copper River also supports populations of coho and pink salmon, but sockeye are by far the most abundant, accounting for more than 90 percent of the river's salmon.
The Copper River sonar site was established to monitor upper river and hatchery stocks of sockeye salmon. Upper river sockeye spawn in tributaries upstream of the sonar site and represent the largest return of sockeye to the river. Hatchery sockeye are stocked by the Gulkana Hatchery upstream of the sonar site and represent about 13 percent of the river's total sockeye return. A third component of the river’s sockeye return—delta sockeye—spawn in tributaries and lakes below the sonar site and are monitored with aerial surveys. The upper river sockeye that travel furthest—in some cases as far as 300 miles upstream—enter the river when water flows are low and less energy is required to swim against the current. Delta stocks migrate 30 miles or less to reach their spawning grounds and generally enter the river last.
Sockeye salmon destined for the Copper River are harvested primarily by commercial fishermen in Prince William Sound. A smaller number are also harvested by sport, personal use and subsistence fishermen upstream. As of 2011, the was inriver goal 622,000 to 822,000. As of the end of 2010, the five-year average commercial harvest was 1 million and the 20-year average was 1.3 million. In 2008, 2009 and 2010 sockeye runs were well below average.