Effects of Density on Production of Hybrid Catfish in Intensively Aerated Earthen Ponds where Dissolved Oxygen is Not a Limiting Factor

Abstract

Research has demonstrated that by maintaining the minimum dissolved oxygen (DO) concentration in earthen ponds at or above 3.0 ppm, feed intake and growth of Channel Catfish Ictalurus punctatus, Blue Catfish I. furcatus, and hybrid catfish (female Channel Catfish × male Blue Catfish) may be doubled relative to those achieved with the oxygen management regimes typically used on commercial catfish farms. In earlier studies using only emergency aeration or low levels of fixed aeration, the direct effect of stocking rate has been confounded by lower morning DO concentrations in ponds stocked at higher densities due to higher feed input and fish biomass. Although higher stocking rates in those studies did produce greater yields, individual fish growth and feed intake may have been impacted by lower DO levels while appearing to be a direct density effect. In this study, production of hybrid catfish, which were fed daily to satiation in earthen ponds with no water exchange, was compared at low (5,000 fish/acre) and high (20,000 fish/acre) stocking rates while using controlled intensive aeration to maintain a minimum DO over 3.0 ppm in all ponds through the study. We achieved an average net production of 27,704 lb/acre at the higher stocking rate compared to 10,176 lb/acre at the lower stocking rate. Although this is the highest yield reported thus far in traditional static‐water earthen ponds in the southern USA, it may not be the maximum production possible. The average weight of harvested fish was higher at the lower density (2.2 lb versus 1.6 lb), but the feed conversion ratio was identical (1.8) at the two densities. Our data indicate that when morning DO is maintained above limiting concentrations, other factors such as direct density interactions (aggression and/or inhibitory pheromonal feedback) and/or water quality variables unrelated to morning DO—specifically un‐ionized ammonia—may play a role in catfish feed intake and growth but not food conversion.

Factors affecting feed conversion ratios in US commercial catfish production ponds

“…Mean monthly minimum DO in low treatments ranged from 1.4 to 2.5 mg/L in subsequent studies, with the high DO concentration ranging from 4.3 to 4.5 mg/L. In E. L. Torrans and Ott (2019), while the trigger DO concentration for aeration was 3 mg/L for both treatments, stocking densities differed greatly (12,355/ha and 49,420/ha). The low DO concentrations resulted in indirect effects of slower growth, longer time to reach harvest size, and increased risks of mortality (L. Torrans, 2011).…”

“…Torrans et al, 2012L. Torrans et al, , 2015E. L. Torrans & Ott, 2019) and split-pond production (Tucker et al, 2014;Tucker & Kingsbury, 2011), thereby reducing production costs, enhancing economic sustainability, and improving market competitiveness with low-priced imported products (Kumar et al, 2016(Kumar et al, , 2020Kumar & Engle, 2017a;Kumar, Engle, Hanson, et al, 2018).…”

“…More recent verification programs have sought to validate experimental findings of increased yields from intensive aeration (E. L. Torrans, 2005, 2008; L. Torrans, 2011; L. Torrans et al, 2012, 2015; E. L. Torrans & Ott, 2019) and split‐pond production (Tucker et al, 2014; Tucker & Kingsbury, 2011), thereby reducing production costs, enhancing economic sustainability, and improving market competitiveness with low‐priced imported products (Kumar et al, 2016, 2020; Kumar & Engle, 2017a; Kumar, Engle, Hanson, et al, 2018). Verification results of hybrid catfish production in intensively aerated ponds showed that yields in intensively aerated ponds (Table 2) were twofold to threefold greater than those managed with less intensive, traditional methods (Table 1).…”