Studies on the surface mixed layer and its associated thermocline off the west coast of India and the inferences thereby for working out a prediction system of the pelagic fisheries of the region

Abstract

The thermocline in the sea, which separates the warm mixed layer at the top and the cold stratified layers below, is important from many aspects. The greater the depth of the thermocline the more will be the water column of the mixed layer enriched with dissolved oxygen which will be available for sea life. The vertical distribution of nutrient salts depends upon the situation of the thermocline (Graham, 1954). The depth of the pelagic shoals depends largely on the vertical extension of the mixed surface layer (Mela and Laevastu, 1962). The vertical extent of the mixed surface layer is also important from the view point of the vertical distributions of the buoyantly floating eggs and larvae of the pelagic fish which are affected by the vertical turbulence occurring in the layer (King and Hide, 1957; Silliman 1950).