DIURNAL VARIATION IN THE CATCHES OF DEMERSAL FISHES IN THE NORTH WEST REGION OF BAY OF BENGAL DURING 1959-60

Abstract

During the pericxl November 1959-Ootober 1960, the Government of India
trawler M. T. Ashok carried out exploratory trawling for demersal fishes, both
during day and night, off the coasts of Andhra and Orissa between latitudes
17°-40' to 20°-10' N and in depths ranging from 5 to 64 metres. Six major groups of
fishes viz., sharks and skates, rays, catflshes miscellaneous big and small fishes and
prawns in the catches showed diurnal variations. The catches of sharks, skates,
miscellaneous fish and catfish were heavier during the day than night, irrespective
of the area of capture and depth. Prawns and rays, however, yielded better
catches at night.
No definite trends could be seen in the seasonal variations of the above
six groups in 17°-40' N and 18°-10' N latitude zones and also at two depth-ranges
of 35-44 m and 45-54 m. Further, analysis was made of the seasonal variations
of the six groups at two depth-ranges 35-44 m and 45-54 m, but no definite trends
on their abundance could be discerned.