Fish stock assessment is a scientific effort that entails collecting, analyzing, and reporting demographic information to determine changes in the abundance of fishery stocks in response to fishing and predict future trends of stock abundance. Effective fisheries management requires an understanding of the impacts of fishing at the level of fish stocks supporting the fishery.

To provide the required data and information for the various water bodies, a resource monitoring program based on a number of methods are put in place. The methods included but are not limited to Catch Assessment and Frame Surveys that deal with the harvests and means of harvesting respectively; state-of-the-art hydroacoustics techniques, Trawl Surveys, Biological, Environmental surveys and other relevant surveys that examines the status of the fish stocks, their biology and interactions among themselves and with the environment. Stock assessment thus, synthesizes all the data and information generated so as to provide a common understanding on the status of the stocks, fisheries, and environment of the lake.

Fresh Water system Directorate regularly undertake Stock Assessment in the inland lakes (Lake Victoria, Turkana, Baringo, Naivasha) and rivers (Nzoia, Nyando, Sondu Mirius) to evaluate the status of fish stocks and provide fisheries managers with the information that is used in the regulation of a fish stock.