Application of Ocean Colour Monitor chlorophyll and AVHRR SST for fishery forecast: Preliminary validation results off Gujarat coast, northwest coastof India

Quantitative analysis of sea surface temperature (SST) and chlorophyll impr ove our understanding of circulation and distribution of phytoplankton popu lation in water masses. In this study near synchronous IRS P4 Ocean Colour Monitor (OCM) derived chlorophyll and NOAA AVHRR derived SST are used for e xploring fishery resources. Ocean Colour Monitor data were atmospherically corrected using long wavelength approach. Ocean Chlorophyll - 2 (OC2) bio-o ptical algorithm was applied to corrected radiance to calculate chlorophyll concentration. Multi channel sea surface temperature (MCSST) approach was adopted for estimation of SST from split window of NOAA AVHRR. Both data se ts were geometrically corrected and registered with master image of north w estcoast of India so as to generate geo-coded chlorophyll and SST images. S ea surface temperature contours generated and overlaid on chlorophyll image s to generate composite images. These composite images were interpreted for generating experimental fishery forecast along the Gujarat coast. Differen t types of the oceanic features like, coastal fronts, fringe fronts, rings, mushrooms, meanders and features shaped as tongue and mushroom, jet etc. w ere selected for forecast. The information was disseminated to Porbandar fo r validation. Gill-netters were used for experimental fishing. Suggested ar eas were located using global positioning system (GPS). The feedback receiv ed from fishing sites were analysed. The catch per gill net operation was n ormalised and compared with month wise normal catch available around Porban dar. About 2-3 fold increase in the catch in potential fishing zones (PFZ) area was observed. The frontal positions in chlorophyll image coincide with temperature boundaries at some locations. This coincidence indicates that physical and bio-chemical processes are closely coupled at these locations and can be used for identification of potential fishing zones (PFZs).