The impact of cottonseed meal condition on water quality, zooplankton densities, and sunshine bass production when used as an organic fertilizer in ponds

Abstract

Abstract Objective Cottonseed meal is applied to sunshine bass (female White Bass Morone chrysops × male Striped Bass M. saxatilis ) fry rearing ponds as an organic fertilizer to stimulate plankton development. The efficacy of cottonseed meal as a fertilizer following long‐term storage and degradation is unknown. The use of degraded and undegraded cottonseed meal were compared during the production of sunshine bass fingerlings in lined 0.4‐ha ponds. Methods Filling ponds were fertilized repeatedly between 13 days before and 6 days after fry stocking, and water quality, zooplankton, and 41–48‐day fingerling production were monitored. Adequate phytoplankton and zooplankton densities were maintained using cottonseed meal of both conditions. Result Cottonseed meal condition had no significant impact on any fish production metric. The degraded cottonseed meal appeared to release nitrogen more readily as indicated by higher prestocking NH 3 ‐N concentrations. Higher nutrient availability likely stimulated primary productivity at a faster rate, leading to higher dissolved oxygen, pH, and zooplankton densities during the first half of the pond cycle. The ponds fertilized with degraded cottonseed meal required more intensive water quality management to maintain adequate dissolved oxygen and pH for sunshine bass fry. However, poststocking water quality parameters were within species tolerance ranges. Conclusion The study confirmed that degraded cottonseed meal can be used as an organic fertilizer in sunshine bass fry rearing ponds without compromising fingerling production, provided ponds are managed appropriately.