Technology unveiling catfish spawning secrets PDF Print E-mail
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Sunday, 26 August 2007 20:00

From the Missouri Department of Conservation --

Researchers are fishing for information to help manage Missouri catfish.

DALTON, Mo.-"Hey, guys, would you turn off your depth finders. It sounds like a techno party down there."

Danny Garrett, a doctoral candidate from the University of Missouri, was at the helm of an 18-foot johnboat on the Missouri River. Beside him, Research Assistant Brook Steinkoetter was holding a length of PVC pipe over the side of the boat. The pipe held a hydrophone, a microphone for listening to underwater sounds. It was picking up pulses from the other boats' sonar units, making it difficult to hear what they were listening for.

When the other boats' electronics switched off, they heard a clear, cricket-like chirp emanating from the mocha-colored water. Within moments, another electronic gadget decoded the complex series of tones in the high-pitched chirp. Checking his records, Garrett identified the sonic transmitter as one that he had surgically implanted in a 25-pound flathead catfish weeks earlier.

Garrett and his crew are working to learn more about where and when catfish spawn in the Missouri River and its tributaries. His field research is funded by and conducted in cooperation with the Missouri Department of Conservation. It is part of the agency's larger effort to amass a body of knowledge that will permit systematic, scientific management of catfish populations statewide.

"He's right here," Garrett shouted, pointing to the water beneath his boat. With that, Conservation Department workers in the other two boats went into action. The larger boat took Garrett's boat's place above the unsuspecting catfish and started a generator that pumped low-voltage electrical current into the water. The current, though harmless, temporarily disables fish, which float to the surface where they can be netted.

Garrett and the third boat's pilot swung into position downstream from the shocking boat. Moments later, workers were scooping up fish with long-handled nets. The boats darted left and right to intercept floundering fish, ignoring those too large or too small to be the tagged fish. They soon hauled in a hefty flathead with a healed incision in its belly.

"Woo-hoo!" exulted Garrett. "That's the biggest one we have ever recaptured."

The three boats made for shore, and Steinkoetter prepared a hypodermic needle to draw blood from the fish. Hormone levels in the sample would reveal whether the fish was preparing to spawn, in the midst of spawning, or past its annual reproductive period. This information, combined with information about the location of fish throughout the spring and early summer, will reveal where and when Missouri River catfish lay their eggs.

Basic information of this sort has been known about sunfish, largemouth and smallmouth bass, crappie and trout for years. It formed the basis for successful management programs for those species. Knowledge about catfish behavior and population dynamics has been harder to obtain because their habitat and behavior are different than those of other fish. The Conservation Department launched a program three years ago to fill this information void.

"We went through this same process with other game fish," said Fisheries Division Chief Steve Eder. "You start by learning all you can about the species' biology and what anglers want. Then you feed your data into population models and come up with experimental fishing regulations that continue to protect fish populations while addressing the desires of various angling interests. You test the regulations in a few areas, track the results and fine tune the seasons, methods and limits to get the desired results and report back to anglers on the changes in the fishery. When you are done, you have management strategies that work."

The Conservation Department recently asked anglers about their desires for catfishing on the Missouri River through a series of public meetings. The agency also conducted statewide surveys in 2002 to learn who catfish anglers are and what they want.

The agency learned that some anglers want to catch lots of catfish. Since channel catfish are the most abundant catfish species, and they thrive in the state's many farm ponds, public lakes and large reservoirs as well as in most streams, that is where most people pursue them.

Special regulations on some areas restrict the harvest of channel catfish. In most waters, anglers may keep up to 10 channel catfish daily, with no length limit. Channel catfish do not grow as large as the other two species, so the Conservation Department does not plan to change regulations on that species.

However, many anglers said they want to catch a larger number of big catfish. On average, their idea of a big catfish was one over 20 pounds. Flathead and blue catfish grow bigger than channel cats, so the Conservation Department is concentrating on them to meet the desires of these anglers.

The Conservation Department recently unveiled plans to test experimental blue and flathead catfish regulations on an 82-mile stretch of the Missouri River from Glasgow to Jefferson City and on parts of two tributary streams in this stretch, the Lamine and Blackwater rivers. The agency is considering the following sets of experimental regulations.

--Option A: Limit of to two flathead and blue catfish in the aggregate daily with a minimum length limit of 30 inches (approximately 11 pounds). Studies indicate that these restrictions would increase the number of blue catfish longer than 30 inches by 89 percent and the number of flatheads over 30 inches by 105 percent. The agency estimates that this option would take about three years to begin paying dividends in pounds of catfish harvested by anglers.

--Option B: Limit of one flathead and one blue catfish daily with a minimum length limit of 30 inches. Anglers would see results faster under this option in return for accepting greater harvest restrictions.

--Option C: Limit of one flathead and one blue catfish over 30 inches and one of each species under 30 inches daily. Anglers would be able to harvest more fish under this option, but it would take longer to increase the number of big fish.

--Option D: Limit of two flathead and blue catfish in the aggregate daily, with only fish under 20 inches and over 30 inches legal to keep. This "slot" length limit would effectively prohibit the harvest of catfish weighing 3 to 10 pounds. Because it would allow the harvest of more small catfish, it might take longer than the first three options to produce results.

--Option E: Other options for a change in regulations can be provided by anglers.

--Option F: No change in the current regulations

"This is an exciting time to be a catfish angler in Missouri," said Kevin Sullivan, who oversees efforts to evaluate new catfish management strategies. "We are on the cusp of changes that will do for catfish what we already have done for bass, crappie, deer and turkeys. In the future, we will be able to deliver what anglers tell us they want in terms of size and number of catfish. It all starts with laying a solid foundation of knowledge."

Sullivan said the Conservation Department will not propose catfish regulation changes until it completes public meetings on the subject. The agency will consider anglers' preferences and research findings during the process of formulating new regulations, if any. No changes will go into effect before March 1, 2009.

For the original article please visit http://mdc.mo.gov/cgi-bin/news/news_search.cgi?item=1187368293,57518,,

To see the accompaning picture visit http://mdc.mo.gov/news/images/fullsize/20070817.jpg

Additional details about the four options are available at
www.mdc.mo.gov/15280. For more information or to express your desires about catfish management in Missouri, visit http://mdc.mo.gov/24, or call (573) 751-4115.

-Jim Low-

Last Updated on Thursday, 23 August 2007 10:23