Validation of Potential Fishing Zone (PFZ) Forecasts from Andaman and Nicobar Islands

Abstract

The annual exploitable fisheries of Andaman and Nicobar Islands are estimated to be 1.48 lakh t of which a meagre 22% is harvested currently. Potential Fishing Zone (PFZ) forecasts based on remotely- sensed chlorophyll concentration and sea surface temperature were applied for harvesting the unexploited marine fishery resources. Simultaneous validation experiments (n = 87) synchronizing with PFZ forecasts within (PFZs) and outside (non-PFZs) the demarcated zones employing different vessel categories viz., gillnetters (n = 50), trawlers (n = 22) and longliners (n = 15) were carried out. Significant disparity in fish catch was observed within and outside PFZs. Fish catch from gillnetters composed of carangids, clupeids, scombrids with Megalaspis cordyla being dominant at PFZ. Carangids, sphyraenids, serranids, lutjanids, thunnids, lethrinids and carcharhinids were reported from trawlers with significantly higher CPUE from PFZs except nemipterids. Fish catch from longliners constituted mainly of carcharhinids and serranids, where the catch of former was found to be significantly higher at PFZs. Alopias spp. (Carcharhinidae), Istiophorus platypterus and Makaira indica (Istiophoridae) chiefly contributed to the fish catch composition during validation of tuna fishery forecasts by longliners which suggests that the productive surface waters favouring pelagic fish aggregation at PFZs has also contributed to the benthic fishery resources of various trophic levels. Gut contents of pelagic fishes harvested from both zones were analyzed and compared. Further, the study investigates the validity of PFZ forecasts based on depth, ecology and area of operation.