Mudbanks and fisheries along the Kerala coast-myth and reality

Abstract

Mudbanks, a unique coastal oceanographic phenomenon occurring along the southwest (SW) coast of India during the SW monsoon season, are synonymous with the fishery of this region. Here we examine the validity of the popular notion that mudbanks directly support rich fisheries, using a high temporal resolution water column data collected from the Alappuzha mudbank region in Kerala during April to September 2014, in conjunction with fisheries data. Our study reveals that the upwelling which occurs during the SW monsoon season along this coast brings oxygen-deficient subsurface water to the upper water column. Escaping the oxygen-depleted waters, the fish aggregate within a thin upper layer allowing easy visual identification and capture of fish shoals. This process occurs throughout the coast and is not confined just to the mudbanks. Mudbank being a calm region, traditional fishermen using non-motorized country craft were able to carry out fishing within this region only during the SW monsoon. With the induction of motorized and mechanized fishing, the link between mudbanks and fisheries is becoming less prominent, although the former still continue to be important fish landing centres.