6/5/2007

Raising Catfish in Cages
by Joe Wilkinson

Approaching the wood-and-wire cages, the boat swung left and came up alongside. On board, Cody Davis and Corey Simpson positioned themselves on either side of the 25-gallon half-barrel. With the lid of the floating cage flipped open, they upended the barrel, pouring a stream of little catfish into the cage.

The 13 cages in Diamond Lake, in Poweshiek County, are home to 7,000 catfish for the summer. "The fish are provided to us free. We provide the labor and the food to bring them up to release size," explains park ranger Ken Vargason, from the Poweshiek County Conservation Department. "They are fed a high protein diet; pellets the size of a pencil eraser. They just grow tremendously." He, Simpson, a park ranger, and Davis, a seasonal worker, met the Department of Natural Resources hatchery truck at the boat ramp for the transfer.

The story is the same in 25 counties across Iowa. The cages protect the three to six inch fingerlings from largemouth bass and other predators. By about Labor Day, the fish will be 10 to 11 inches long, pretty much out of snack range. Catfish do well in close confinement. Other species would suffer stress, be susceptible to disease or being eaten by larger cage-mates.

The journey begins in southern Iowa, at the Lake Rathbun fish hatchery. There, DNR workers wade through catfish ponds, scooping egg masses out of old milk cans, used as artificial spawning 'holes' for brood fish. The eggs are monitored in the hatchery. As they hatch, the fish are raised and over-wintered there. Late the next spring, it's on to the stocking truck for a trip to one of the small lakes across Iowa.

"For us, it means they spend less time in the hatchery," says Department of Natural Resources fisheries technician Chris Mack. "We supply less food. It frees up space sooner and we have room for other fish. We can drop them off here and they continue their growth."

Along with largemouth bass and bluegill, channel catfish make up the backbone of a fish population in these county park lakes, providing the food chain and scavenger element needed for a healthy population. However, there is virtually no successful catfish reproduction in artificial lakes in Iowa. Any which are spawned would quickly become dinner for bass and other predators. That's why stocking is so critical. And with three months in what amounts to a protected chow line, the little cats get a great head start.

And with that start, they're closer to heading home on an angler's stringer. By next spring, maybe even late this fall, the bigger ones will be in the 'keeper' size range. "I would say in the pound and a half to two pound range, that's when people really enjoy them for eating", says Vargason. "Then, we also have the angler that wants nothing but the big fish. We did have some 20-pound catfish showing up already in the creel survey this year. They've done real well."