The influence of mesoscale eddies on a commercial fishery in the coastal waters of the Andaman and Nicobar Islands, India

Abstract

Mesoscale eddies enhance the productivity in a stratified coastal environment by upwelling. The seas around the Andaman and Nicobar Islands have been found to have frequent mesoscale eddy activity. Commercial fishing grounds coincide with upwelling areas associated with cyclonic and anticyclonic eddies and also with areas between two adjacent eddies. There are different eddy zones supporting different types of fishing gears and fish. The current study aims at identifying the different zones of mesoscale eddies in the Andaman Sea and compares the productivity and fishing activity in each of them. Data collected from 454 commercial fishing trips in the Andaman Sea along with maps of sea level anomaly and Moderate Resolution Imaging Spectroradiometer (MODIS) global level 3 mapped thermal infrared (IR) daytime sea surface temperature (SST) from the Aqua and Terra satellites were used for the study. Known upwelling areas such as the periphery of anticyclonic and the core of cyclonic eddies showed higher catches in longlines, ring seines among the fishing gears, and among all the fish species groups. Downwelling areas such as the periphery of cyclonic and the core of anticyclonic eddies showed lower catches with ring seines and the fish species groups. Areas in between adjacent eddies were explored in this study and the fish captures in such areas were found to be different with types of fishing and the target fish group. The study shows results that link eddy activity with the performance of a fishery.

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Acknowledgements

This study is a component of the science investigations carried out by the authors as a part of SARAL (Satellite with Argos and ALtiKa)/AltiKa science team. The authors would like to thank AVISO of CNES (Centre National d’Etudes Spatiales) for altimetry data, PO.DAAC – NASA for SST and OceanColor – NASA for chlorophyll data. The support from the Director, Central Agricultural Research Institute (CARI), in conducting the research study is thankfully acknowledged. Constant support and encouragement from the Director, National Remote Sensing Centre (NRSC), is acknowledged. The authors thank Deemat C. Mathews for his support in the statistical analysis of catch data.