A popular wisdom among bass fishermen is that catching fish is relatively easy. It's finding them that's supposed to be tricky.

A fellow pulls up to a favorite spot, lashes it with casts and nothing happens. "They're not here," he concludes, then motors away in search of wherever fish happen to be.

Now and then, however, we get an inkling that such an explanation doesn't float. Someone will mumble something about having seen fish down there with his sonar unit, but, he complains, they wouldn't bit.

One of fishing's greatest puzzles, one of the things that keeps us from mastering the game, is the uncertainty in explaining the fruitless cast. When we don't catch a fish, we really don't know why.

Lacking x-ray eyes, for which anglers have long wished (although electronics put us close), we can't tell if a non-productive cast failed because it didn't come close to a fish or if it indeed was scrutinized by a fish that simply didn't want what we offered.

Fishermen may get some revelation this spring from some studies being conducted by TVA. In April, TVA fisheries biologist Donnie Lowery will conduct catch depletion research on Kentucky Lake, a study that makes close comparison between what fishermen do or don't catch and what potential catch was there all along.

In a way, this study gives us those x-ray eyes that we've always wanted.

It works like this: A cove of six to 10 acres in size is isolated from the rest of the lake with netting across the mouth. Bass in the cove are contained, and other bass are kept from entering during the study.

Two boats, each manned by two competent, experienced bass fishermen, assault the test cove for an hour of hard fishing. They measure and fin slip the fish they catch, then release them back into the cove.

After the test fishing, a TVA craft then enters the same water and electro-shocks the are. All bass that are stunned are scooped, measured and cataloged, then released outside the net. Multiple passes with the shocking boat, passes at one-hour intervals, eventually reveal most if not all of the bass that are there.

After all is said and done, the effectiveness of the fishing can then be directly compared with the potential catch revealed by electro shocking.

The shocked fish survive, incidentally, and the cove reverts to normal shortly after the nets are removed. Normal fish movements restock the cove within a few hours.

Lowery already has conducted catch depletion studies on other TVA reservoirs, and he said fishermen, too, usually are shocked -- mentally, at least -- by the results. They most often are overwhelmed by the number of fish that were available and could not be caught, he said.

"On Guntersville Lake (in Alabama), we had four fishermen who were only able to catch two bass during the hour -- one 12-incher and one 10-incher," Lowery said. "Then we went back with the shocking boat and got 76 bass of harvestable size on our first run. We found seven bass that went between six and eight pounds.

"This was in a cove that wasn't considered a great bass fishing area, either," Lowery added.

In all past catch depletion studies, fishermen have never caught as much as one percent of the bass available, Lowery said.

"I'm a bass fisherman, too, so the findings are interesting to me," he said. "I think it just proves that you can't always trigger fish into striking a lure. Sometimes you can find them and know they're there, but you still can't make them bite."

Lowery said results of the testing go to state fisheries agencies to help in their management decisions. Findings thus far on TVA lakes generally reflect strong bass populations, while angler attitudes are helping keep those populations healthy, he said.

"We're finding that most bass fishermen, almost 70-percent , do practice catch-and-release fishing these days," he said. "That and size and creel limits are improving the quality of the fish and contributing to good fish stocks."

And catch depletion studies so far suggest that fishermen aren't exactly wearing out the bass populations around them anyway.

~Steve Vantreese is outdoors editor of The Paducah Sun.