Effects of Organic Fertilization and Organic Diets on Production of Channel Catfish in Earthen Ponds

Abstract

AbstractWe evaluated the effects of organic fertilization and “organic” diets on the production of channel catfish Ictalurus punctatus. During fingerling production, four 0.4‐ha earthen ponds were fertilized with a combination of inorganic fertilizers and regular cottonseed meal (control ponds) and four were fertilized with organically produced cottonseed meal only (organic ponds). Swim‐up fry were stocked into each pond at a rate of 247,000 fish/ha and fed a control or organic diet daily to apparent satiation for one growing season. During food fish production, overwintered control and organic fingerlings (mean initial weights = 50.8 and 44.8 g/fish, respectively) from fingerling production were each stocked into five 0.04‐ha ponds at a rate of 14,800 fish/ha and fed a control or organic diet daily to apparent satiation for one growing season. Fish were raised with a predetermined organic program that was largely based on U.S. livestock organic standards, since there were no organic aquaculture standards available in the USA. During fingerling production, ponds fertilized with a combination of inorganic fertilizers and cottonseed meal had higher total N and P and higher abundances of preferred zooplankton taxa than did ponds fertilized with organically produced and processed cottonseed meal alone. Gross production of fingerlings in organic ponds was lower than that in the control ponds. During food fish production, there were no differences in production characteristics and carcass yield between conventionally and organically grown fish. However, organic fish had lower fillet yield and higher body fat than did control fish. The slightly higher body fat observed in organic fish mainly resulted from the slightly higher fat content in the organic diet. The results from this study indicate that channel catfish can be grown from swim‐up fry to food size organically, but gross production during the first season may be lower in organic ponds than in nonorganic ponds, in part because preferred zooplankton taxa are produced in lower abundances in the ponds fertilized with organic cottonseed meal.