Fish Yields in Relation to Water Quality and Plankton Production in Managed and Unmanaged Fresh Water Ponds

Abstract

Managed and unmanaged (unmanaged) extensive culture fisheries systems in small village ponds in the district of Kurukshetra, Haryana, India were explored and analyzed focusing on the relationship amongst water quality, production of fish food organisms, fish yields and management actions. In unmanaged ponds, fish growth/yield and dissolved oxygen were low and ammonia, chlorides, calcium, total hardness, magnesium, phosphates and biochemical oxygen demand were higher when compared against managed ponds. The differences are likely due to higher organic load in the unmanaged ponds arising from domestic sewage and cattle entry from non-point sources. Variations observed in the phytoplankton population for the unmanaged and managed ponds were insignificant, however, zooplankton were high in unmanaged ponds. The NPP was higher in the unmanaged ponds in contrast to managed ponds. From the finding it seems that Fish production does not tends to depend significantly on the extent of primary production. Significant direct relationship between fish production and primary productivity could not be determined in this study. However, multivariable relationships were detected through multivariate statistical analysis. Such relationships are not straightforward as a variety of factors including ammonia production, organic loading and the quantity and quality of fertilizers play important roles in influencing such relations.