Dead striped bass are piling up by the hundreds in Lake Norman, threatening a popular game fish that draws tournaments, tourists and their dollars to the state’s largest man-made lake.

State wildlife officials think they know why the fish are dying and are weighing solutions – including pulling the plug on stocking the popular fish.

Between July 27 and Aug. 3, 705 dead striped bass were collected from Lake Norman, according to the N.C. Wildlife Resources Commission. The number is smaller than fish kills found in the dog days of previous summers, but what’s troubling is that the kills keep happening year after year.

One suspected culprit is the alewife, a fish state officials believe was stocked in the lake without permission more than a decade ago as food for the striped bass, according to Chris Waters, with the N.C. Wildlife Resources Commission.

Anglers had been lobbying the commission to stock alewives to help grow bigger bass in Lake Norman, but the commission balked, saying the environmental impact of stocking the alewife was unclear.

“When they showed up, we were confident that someone had stocked them,” Waters said. “It’s anglers, specifically anglers that like striped bass.”

Striped bass, or stripers, are a hardy game fish that can live in saltwater and freshwater. But all fish need oxygen to survive, and as the stripers descend to the lowest level of the lake to feed on the alewife, they become trapped, unable to climb above the middle level with its low oxygen levels. That middle level starts to expand as summer goes on, further endangering the stripers.

“It’s a function of the natural stratification of a deep reservoir,” Waters said. “Typically, the fish wouldn’t have a reason to go deep, but when the food goes down, the striper will chase them.”

Waters said the state is considering its options. Striped bass can’t reproduce in Lake Norman, so the state puts about 162,500 fish in the water each a year. But if the fish keep dying, taxpayer money is wasted. State officials are considering stocking the lake with a hybrid bass, which can’t tolerate the cold temperatures at the bottom of the lake and would stay near the top, where oxygen is plentiful. But the environmental impact of the hybrids is unclear – they could harm fish populations in South Carolina. The commission is also considering whether to simply stop stocking striped bass in Lake Norman.

Gus Gustafson, a guide on Lake Norman since before it was dammed and a columnist for the Observer’s community publications, said fishermen don’t agree with the commission’s conclusion about the alewife. He says the stripers are dying because of thermal pollution from the McGuire nuclear plant and global warming, which he believes are diminishing oxygen levels in the lake. Still, he says, fisherman support introducing hybrid bass to the lake and think the commission should do so.

“Their responsibility is to have fish in the lake for the fishermen,” said Gustafson. “They need to give the fishermen a viable fish to catch in place of the striper. I’ve been 25 years begging them to do that.”