Journal of the Marine Biological Association of India

Volume 32 Issue 1&2

Influence of some bottom water oceanographic features on demersal fish catches in the Arabian Sea off Manjeswar.

D. E.Nathaniel, T. N. Ramana and M.P.M Reddy

In order to understand the possible reasons for the month wise fluctuations of demersal fish catches obtained by experimental bottom trawling at 20 m depth in the Arabian Sea off Manjeswar, certain oceanographic features from bottom waters such as temperature salinity, dissolved oxygen and water currents have been correlated with the fluctuation demersal fish catches in the area.

Throughout the period of investigation, the trawl catch obtained when the trawling was performed against the bottom water current was more than the trawl catch obtained when the trawl net was operated along with or across the current. This was attributed to the increased trawling efficiency based on the knowledge of the bottom water current. A significant direct positive correlation occurred between bottom water temperature and trawl catch 65 kg during March coincided with the highest bottom water temperature of 29.2oC and the lowest catch of 7.5kg during September coincided with the lowest temperature of 25.9oC. There was a direct correlation between trawl catch and bottom water salinity for all the months except during April and May. Remarkably lower catches were obtained during May and September which coincided with the lowest oxygen values of 3.78 and 3.45 ml/l during these months respectively.

Date : 31-12-1990