Biologists with the N.C. Wildlife Resources Commission don't have any solid reason for the uptick in crappie fishing in Lake Norman. The Commission samples crappie with a fall netting operation every third year; 2012 is the next scheduled survey.

That's when they'll examine fish for weight, length and age and determine by the number of fish they catch in their sample and the health of fish whether or not a change has taken place.

Lawrence Dorsey of Albemarle, a Commission biologist whose territory includes most of the lake's southeastern shoreline, said that short-term improvements in a fishery can be caused by any number of factors, but a series of excellent spawns and year-classes of fish is usually one of the keys.

"It's very difficult to isolate one thing that causes something a change in a fishery," Dorsey said. "You can examine a number of different factors; we've tried to do that. We've measured things like water flow through a reservoir to see if there's any bearing. It's just hard to say that one thing caused any change."

Dorsey said that anecdotal reports from fishermen at Lake Wylie, which is two impoundments downstream from Lake Norman, about a similar change in the crappie fishery. "You heard about Wylie that nobody caught many fish, but the ones that caught were nice ones," he said. "Now, we're hearing that fishermen are catching much better numbers of fish. Maybe it's the same thing.