An In-pond Raceway System Incorporating Removal of Fish Wastes
An aquaculture system called ?in-pond raceway (IPR)? was studied for channel catfish (Ictalurus punctatus) production. The raceway was a rectangular-shaped box (4.9~ I.2 m x I.2 m high), built from treated lumber and suspended between walkways of a floating pier. A set of airlifi pumps located at the head-end of the raceway circulated pond water into the raceway. The raceway had an approximately 4% bottom slope along the 49 m length to assist the movement of fish wastes cfeces and uneaten feed). In 1992 four raceways were stocked with an average of 2078 fingerlings per raceway. Mortalities during the 124-day culture period averaged 341 j&h (164%) per raceway. The growth rate averaged 1.29 g day-t with an average food conversion ratio (FCR) of 1.95. The average total weight of the harvested fish was 297.3 kg per raceway (52.2 kg mm:?). A total of 201 m3 of fluent containing fish wastes was removed and sampled. The samples were analyzed for concentrations of total solids, BOD and nutrients (nitrogen and phosphorus). The system was intended to remove settleable wastes with primary and secondary waste collectors. Soluble wastes were allowed to enter the pond.