Arabian Sea oceanography and fisheries of the west coast of India

The physical and chemical forcing, which drives the Arabian Sea production is now fairly understood. The main attributes which contribute to the productivity are (1) the boundary and open process, which manifest as upwelling during summer monsoon and (2) cooling in the northern Arabian Sea during winter. These bring in higher amount of nutrients into the upper ocean, which enhance primary productivity and we examine how these might contribute to the fisheries along the west coast of India. The highest catches are between October and March. From an oceanographic point, this region can be divided into two areas: south of 15 degreesN and north of this latitude. Although the fish catches from these two areas are fairly equal, there is considerable difference in the composition. In the south, planktonivorous fishes dominate, whereas in the north carnivores are more abundant. This appears to be a puzzle, and not reported hitherto. Based on the lower food-web, which appears to be similar in the two regions, we seem to be unable to explain this difference.