Hydrography of Fishing Grounds of Arabian Sea off Mangalore

Abstract

Hydrographical parameters, namely temperature, salinity, disi>olved oxygen and density of the fishing grounds off Mangalore extending over an are2. of ca 850 km2 have been studi~d during March 1976-March 1977. Twelve stations o.long three transects up to 50 m Isobath were located for sampling. The vertical distribution of temperature show three distinct phases, namely, a period of conspicuous variation, a short intermedjary phase and a period of thermal stability. The disso]ved oxygen of the bottom waters was drastically low during September. Salinity :fluctuations were not considerable betweenmonths an~ depths. Dense waters existed over the shelf region, especially along the bottom dunng Septemb~r and to a certain extent in October also. The distribution patterns of temperature, dtssolved oxygen . and density cl~arly indicate the movement of cold, dense, oxygen-poor- bottom waters from greater depths to the upper reaches of the shelf during September.