 Due to the biomass of phytoplankton and presence of cool water in these regions, upwelling zones can be identified by cool sea surface temperatures (SST) and high concentrations of chlorophyll-a.The increased availability of nutrients in upwelling regions results in high levels of primary production and thus fishery production.Approximately 25% of the total global marine fish catches come from five upwellings that occupy only 5% of the total ocean area.