passing of boats with outboard motors within a few feet of the 

 cage because rate of gain was faster in those fish caged in the 

 boat slip than in fish caged in undisturbed ponds. 



In a final test we compared the production of channel 

 catfish in a modified raceway containing 262.5 cubic feet (7.43 

 cubic meters) of raceway volume, and a flow rate of about 80 GPM, 

 with the production obtained from feeding an equal number of 

 fish (1250 per acre) with a demand feeder in a 1-acre (0.4-hectare) 

 pond. Final standing crops differed by less than 1 percent, and 

 rate of food conversion was lower in the raceway than in the pond 

 (1.06 vs. 1.21) . The high rate of flow of unscreened reservoir 

 water through the raceway provided raceway fish with much sup- 

 plementary food. 



This report presents information obtained from a series 

 of miscellaneous investigations performed over the years 1968 

 through 1972 at the Sam A. Parr Fisheries Research Center in 

 Marion County, Illinois. All studies involved the channel cat- 

 fish ( Ictalurus punctatus ) . The principal studies were conducted 

 in a series of 1-acre (0.4-hectare) ponds,- additional studies 

 were made in smaller ponds and a raceway, and in cages floated 

 in the 585-acre (236. 7-hectare) Stephan A. Forbes reservoir. 



PINGERLING CHANNEL CATFISH AT DIFFERING DENSITIES IN A DIVIDED POND 



Material and Methods .--Our initial experiment utilized a 

 small (1/3-acre) (0. 14-hectare) , rectangular pond which was con- 

 structed to be six feet (1.8 meters) deep in the middle and shal- 

 low at each end so that a partition across the middle provided 

 two sections which were identical in all respects except their 

 orientation to the sun. This permitted two fish populations to 

 be physically separated but to share water circulating through 

 a 1/4-inch-mesh (6.4-millimeter mssh) separating screen. It was 

 our intention to establish differing densities of fish populations 

 in similar halves of the pond and to determine to what degree the 

 effects of crov;ding the catfish might be minimized by the dilut- 

 ing effect of the circulating water. We believed that this would 

 provide information as to the practicality of confining and feed- 

 ing a dense population of chr.nnel catfish in a fenced-off, manage- 

 able portion of a largor and less manageable body of water. On 

 June 19, 1968, the pond v;as stoc]:?.d with 300 finger lings (average 

 total length 1'.3 inches; 13.4 centimeters) in each half, equiva- 

 lent to a density of 2,000 fish per acre (4,942 fish per hectare). 



