Intra and inter annual patterns in coastal upwelling, its relation with primary productivity and marine fish catch trend at south west coast of India

South-west coast of India is the area where the influence of upwelling on pelagic catch is observable as compare to other upwelling zones of India. Various studies has carried out on upwelling patters of SW coast and the studies studies which relates the pelagic catch and upwelling is restricted to states only and not studied all SW coast as whole. In this study, the influence of upwelling on pelagic catch and productivity is studied throughout the SW coast. The online datasets of environmental parameters like meridional and zonal component of wind for calculation CUI or Ekman transport, chlorophyll-a and Sea Surface Temperature (SST) were downloaded from the online public domain; it was cut for 200m depth and monthly mean was calculated in R software . Pelagic landing data was taken from the CMFRI database. To make study more precise, whole SW coast (8°N to 16°N and 73°E to 78°E) was divided into small grids or stratum. The time series of these environmental parameters was done with pelagic fishes like Oil Sardine and Indian Mackerel. When these pelagic catch and environmental parameter was cross correlated, the Oil Sardine found significant with Ekman transport (r = 0.34) at lag -5 and chlorophyll-a (r = 0.46) at lag 2 and 3. Also, Indian Mackerel with Ekman transport was also found significant (r = 0.17, r = 0.27 and r = 0.24) at lag -6, -7 and -8 respectively and with chlorophyll-a (r = 0.40, 0.46 and 0.50) and very significant at lag 1, 2 and 3 respectively. This result implies that the catch of Oil Sardine is influenced by coastal upwelling and are high during post-monsoon season which extends till the beginning of pre-monsoon and in case of Indian Mackerel catch is high during post-monsoon period which extend till pre-monsoon. And this result is also assessed by catch anomalies of Oil Sardine, Indian Mackerel, Ekman transport and chlorophylla.