Helping protect Alaska's ecosystem when millions of sockeye salmon migrate each year are commercial fishermen looking to reel in massive paydays. To preserve the environment and sustain the fisheries for future migrations, crews harvest up to 70 percent of the salmon during a four-week season. This series documents the drama on Bristol Bay, focusing on the work of five captains and their crews who best represent the 1,800 competitors angling for a potential fortune swimming just below the surface.