Zooplankton abundance in the continental shelf waters of the northeast coast of India

Higher concentrations of zooplankton standing stock and population occurred in the region off Chilka lake and Paradip (19° 10'N-19° 55'N and 85°09'E-86° 50'E) during January and off Visakhapatnam (17°30'N- 18°28'N and 83°14'E- 84°29*E) during November and April. The most productive period along the northwestern part of the Bay of Bengal was the northeast monsoon season (October-January) followed by the premonsoon season (February-May). High abundance of copepods, chaetognaths, siphonophores, cladocerans, fish larvae, planktonic molluscs, amphipods, foraminifers and larval polychaetes constituted the northeast monsoon maximum. Very low biomass values were recorded during the southwest monsoon season (June-September). The neretic zone up to 50 m depth was rich in zooplankton population during northeast monsoon and further to a lesser extent up to 100 m during the premonsoon season. However, a steady decline was evident with increasing depth zones. The less saline northern part exhibited remarkable differences in the abundance of the population and standing stock in such a way that 63% of the total was confined to the northern region. Fish eggs were predominant during February-May and larvae in July and January-February. The peak period of the zooplankton population coincided with the maximum landings of the pelagic and demersal fishery resources of the northwestern coast of the Bay of Bengal.