MOBILE — Alabama has a new fishing rule aimed at protecting an aging catfish population prowling the murky depths of its many waterways.

Conservation officials hope it discourages out-of-state fishermen from hauling away big catfish to put them in pay-to-fish ponds up North. The catch-limit rule, backed by trophy anglers, also covers local fishermen, including some who doubt there’s a shortage of big catfish.

The state in October began enforcing a new regulation that says only one catfish longer than 34 inches may be harvested each day by an angler. It’s the state’s first catch limit on the nongame catfish.

The Department of Conservation and Natural Resources regulation also says live blue catfish or flathead catfish longer than 34 inches cannot be taken out of Alabama without written approval from the state’s conservation commissioner.

“If you catch a 32-inch fish it can be taken — live or dead,” said state fisheries director Stan Cook in Montgomery. Alabama does not have a limit on the number of smaller catfish that may be kept.

Cook said the out-of-state pond operators began showing up in Alabama waters after Tennessee passed a similar catch-limit rule and raised fees on out-of-state licenses. Cook expects they may shift into Mississippi waters now that Alabama has cracked down.

Larry Pugh, the assistant fisheries chief for the state of Mississippi, said there’s been some discussion about a catch limit in that state because of the actions taken by Tennessee and Alabama, but nothing has been approved.

Tennessee’s catch limit doesn’t bar taking the big catfish out of state.

“We’ve limited access to out-of-state licenses by raising the fees,” said Tennesse’s fisheries chief Bill Reeves in Nashville. “That doesn’t really stop anybody, but it does make people stop and think before they pay that kind of money to be part of it.”

The big catfish are highly sought by operators of pay-to-fish ponds in Ohio, Indiana and Illinois. The operators were coming down with nets to scoop up the big ones, Reeves said.

Arkansas has a similar catch-limit rule for the Mississippi River bordering Tennessee, but not for the entire state, a fisheries official in that state said.

Alabama’s regulation was based on Auburn University research on Wilson Lake, prime catfish waters in north Alabama.

The research showed that a regulation protecting large catfish would be accepted by most anglers. But retired commercial fisherman and trapper J. B. McIntire of Jackson County in northeast Alabama said he organized a petition drive against the catch limit.

McIntire, 65, contends there’s no shortage of big catfish in state waterways.

“Now is the time to catch big ones while they are bunched up (in cold waters),” he said in a phone interview.

McIntire said conservation officials should have been required to prove a shortage before approving the catch limit. He said he has asked his legislative representative to try to revoke the catch limit regulation.

McIntire said he’s fished over 50 years in Jackson County and recalled when the number of commercial fishermen in his area totaled about 100.

“Today there might be two or three,” he said. “But nobody has seen a shortage of fish.”

State biologist Dan Catchings at Lake Guntersville said the aim for the new regulation is to slow the big catfish harvest until further studies could be done, including at Lake Guntersville.

Conservation officials say the larger catfish need some protection because they grow relatively slowly, and even in Alabama’s productive waters, it takes a number of years to replace a large catfish.

Members of the Southern Catfisherman Association recommended a size limit be set and approached conservation officials, who held public hearings in January in Tuscumbia and Guntersville to share Auburn’s data with the public.

The regulation was approved by the conservation advisory board, with members representing all regions of the state, and the commissioner gave final approval.