Primary production and fishery potential of reservoirs of Karnataka

Abstract

Gross and net primary production were investigated with respect to depth in
eleven reservoirs of Karnataka (latitudes between 11058' and 16045' N) from
three main river systems (Cauvery, Krishna and Sharavathi) covering the three
geographical zones of the state. Mean gross primary production (GPP) of all
reservoirs were 1.26 g C/m2/d, was higher in Cauvery basin than Krishna. Surface
photoinhibition occurred in most of the reservoirs during the pre-and postmonsoon
seasons. Mean net primary production accounted for 61% of the GPP.
Mean maximum photosynthetic rate was 63.37 mg C/m3/h with the highest of
117 mg recorded in Nugu reservoir. All the reservoirs under small and medium
category are found to be productive. Among the large reservoirs, Narayanapur
is the most productive and Ghataprabha the least. Based on primary productivity
values, the reservoirs under small and medium category have an estimated
fish yield potential of 200 kg /ha./yr and those coming under large category have
100 kg/ha/yr. Management guidelines to realise the potential yield are presented