Production of sunfish ( Lepomis spp.) and channel catfish ( Ictalurus punctatus) in acidified ponds

Abstract

Sulfuric acid was used to acidify ponds and obtain four different average levels of total alkalinity (1.6, 4.2, 9.6, and 32.8 mg/l as CaCO 3) in fertilized ponds stocked with sunfish ( Lepomis macrochirus and L. microlophus). Each treatment was replicated three times. Concentrations of available carbon dioxide, pH values, phytoplankton abundance, gross primary productivity, and net sunfish production were greater in the highest alkalinity treatment than in the three lower ones ( P<0.05). Sulfuric acid applications also were made at three rates to channel catfish ( Ictalurus punctatus) ponds to provide average alkalinity levels of 2.1, 5.8, and 46.2 mg/l as CaCO 3. Each treatment was used in three ponds, and fish were provided a pelleted ration. Net production of channel catfish did not differ among acid treatments. The different response between the two aquaculture systems resulted because sunfish relied on natural food organisms while channel catfish derived their nutriment primarily from pelleted feed. Therefore, lower natural productivity in acidic waters affected sunfish production but not channel catfish production.