Bottom-dwelling catfish pack a punch

[Hamilton Reef]

Bottom-dwelling catfish pack a punch

http://www.greenbaypressgazette.com/app ... 50629/1233

06/15/08 Patrick Durkin patrickdurkin@charter.net

W EYAUWEGA — Al Niebur goes face to face with countless flathead catfish each year on the Wolf River, so people believe him when he says these pugnacious bottom-dwellers pack more punch than more famous predators like muskies and northern pike.

To prove his point, Niebur pries open the thick, armored lips of a large flathead and nods into its giant maw. Jutting from its white gullet, about a foot below Niebur's hands, is the forked tail of the flathead's cousin.

"He swallowed about a 17-inch channel catfish," Niebur said. "Think about those sharp spines on the dorsal and pectoral fins. You'd think they would puncture a flathead's gut and kill him. But if a fish fits into a flathead's mouth, it's food. You wouldn't believe what they eat. One of our guys found about a 9-inch snapping turtle inside one. How do they digest a snapper?"

Niebur, a senior fisheries biologist with the Department of Natural Resources, is taking part in a study assessing flathead catfish in the Winnebago System. The program began in 1999 when fishermen who target the Wolf River's flatheads worried their size and numbers were decreasing.

The Wolf's flatheads support a fishing culture seldom seen except near the Mississippi River. Resident fishermen can buy a license to use one 25-hook setline and up to five bankpoles, which are long poles equipped with heavy lines and two hooks. Anglers can leave the lines unattended, but must check and remove their catch daily.

The DNR lacked good data on flatheads and the people who pursue them, so it formed a citizens advisory group to learn more about both. One of the group's early moves was to help reduce the daily bag limit to two flatheads and ban commercial fishing for them in 2002.

As the program progressed, the DNR learned it was exploring new scientific ground. Central Wisconsin is about as far north as flatheads live, so only Southern states had much solid information on the fish's fertility, longevity, life history and habitat requirements.

The DNR has used nets, divers, electro-shock equipment and donated fish from anglers to catch and identify more than 1,200 flatheads since 2001. They affix an exterior tag to each flathead and inject a microchip into its scalp. After recording its length, sex and weight, researchers release the fish.

The tags allow researchers to collect data when a flathead is recaptured or caught by anglers, which helps estimate the fish's population and mortality rate. Flatheads on the lower Wolf and upper Fox rivers can live 30-plus years and weigh more than 60 pounds. The study has revealed most Wolf River flatheads spend the winter in Lake Poygan and travel as far as 80 miles upriver to spawn and hang out during summer.

The agency is studying anglers to learn how many flatheads they catch, keep and release. When the study estimated anglers remove at least 33 percent of the population's larger flatheads each year, the joint DNR/citizens committee crafted a proposal in 2007 to reduce the pressure. If approved, the daily limit would drop to one flathead, and anglers could keep only those measuring 30 to 36 inches, or exceeding 42 inches.

"The consensus is that fishermen want more trophy-size flatheads, and this regulation would protect both young and old spawning stock," Niebur said.

He thinks this change would achieve goals without outlawing setlines and bankpoles.

"These guys have been working hard to help assess the flathead population, and their equipment is a unique part of the Wolf River's culture," Niebur said. "Plus, they use the same gear to catch channel catfish, and the channel cat appears to be doing fine."

The research also is documenting the importance of the Wolf's natural shorelines. Flatheads don't spawn along riprap, or walls of metal or wood. Male flatheads build a nest among logjams and large uprooted trees, and guard the nest after females deposit loads of 20,000 to 40,000 eggs. The males remain on post until the eggs hatch and fry disperse.

Niebur said flatheads are aggressive and territorial, and eat or drive away anything that threatens their nest.

Maybe that's what happened to that 17-inch channel catfish. Given the flathead's attitude and the size of its mouth, only suicidal fish venture near its nest.