WASHINGTON — On Sunday night, millions of viewers across the country will tune in to what has become an annual ritual of summer television, a combination of fear and morbid fascination: Discovery Channel’s Shark Week.

Cable television’s longest-running and most popular series celebrates its 25th anniversary this year, proving yet again that Americans have a seemingly insatiable appetite for stories about the ocean’s top predator. But as Silver Spring, Md.-based Discovery seeks to keep its annual shark fest relevant, executive producer Brooke Runnette has begun to build an alliance with national conservationists who have spent years decrying the channel’s programming as simplistic and short-sighted.

In an interview, Runnette, a former news producer who took over the show in 2010, said part of her work is driven by a straightforward motivation to drive audience with fresh material: “What can I still do that’s new, for God’s sakes, after 25 years?”

After all, Discovery already ran “The 10 Deadliest Sharks,” “Anatomy of a Shark Bite” and “Bull Shark: World’s Deadliest Shark,” more than a decade ago. So Runnette has sought to have viewers “see a shark differently,” whether that’s through advanced technology or an alternate story line.

In this year’s version of “Air Jaws,” for example (“Air Jaws Apocalypse,” in case you were wondering), filmmakers have constructed an underwater housing so they could take 1,000 frames of footage a second below the waves.