CHANNEL CATFISH Ictalurus punctatus PRODUCTION IN FLOATING RACEWAYS

Letícia E. Fantini*, Jesse Chappell, Ruy A. C. Corrêa Filho, Jayme A. Povh, Terry Hanson and Fernando Kubitza
 
School of Fisheries, Aquaculture and Aquatic Science, Auburn University (SFAAS-AU) 203 Swingle Hall, Auburn, AL, USA 36849; e-mail: lef0022@auburn.edu
* Scholarship from CAPES - Brazil
 

Floating in-pond raceway systems (IPRS) consist of large floating rectangular cages placed into existing ponds. IPRS generally occupy less than 2% of the pond area, have a constant water flow of highly aerated water and grow fish at a high density. Due to the efficient feed conversion ratio (FCR), effective pond water circulation and easier management of fish stock, IPRS can support a higher fish yield compared to conventionally managed catfish ponds. Research at Auburn University has shown that hybrid catfish (female channel catfish, Ictalurus punctatus x male blue catfish, I. furcatus) can be grown to market size (680 g) in nine months, with survival ranging from 85 to 96%, FCR below 1.60 and gross yield greater than 15,000 kg/ha, while conventionally managed ponds often yield less than 8,000 kg of catfish/ha, with FCR above 2.0.

This study aimed to verify if channel catfish can be raised in IPRS units to a commercial size of 680 g in one growing season at a yield twice as much as the gross yield  recorded in conventional catfish ponds in Alabama (7,800 kg/ha/yr). For this, one floating IPRS was placed in each of four 0.4-ha ponds. Raceways were 64 m3 (4.9 m wide, 10.7 m long and 1.22 m deep) in ponds B1 and B2, and 45 m3 (3.05 m wide, 12.20 m long and 1.22 m deep) in ponds B3 and B4. Each IPRS had an airlift device made of a grid with 12 m of diffuser hose placed under a directional hood, propelled by a 1.5-HP air blower. The airlift device was positioned just before the inlet screen and provided raceways with a constant water flow and maintained adequate oxygen levels during the night and early morning hours. IPRS units were covered with a 25 mm net to prevent bird predation. Catfish fingerlings were stocked into IPRS units in April 2017 and fed a 32% CP commercial catfish pellet once or twice a day depending on water temperature and oxygen conditions. The feed was supplied at will until near apparent satiation. Raceways were inspected daily for the presence and removal of dead fish.

Partial production results are summarized in Table 1. A sequence of bacterial infections in the second month of the study (first Flavobacterium columnare, second Edwardsiella ictaluri) caused losses of fish in all raceways. Fortunately, fish were still small at the onset of those infections, causing minor losses of biomass. The IPRS unit in pond B4 experienced the highest mortality but fish in this unit also have the highest mean weight and highest estimated biomass compared to fish in other raceways. Full trial results post-harvest will be presented.