Exploratory fishing by oceanic drift gillnetting and purse seining in the Lakshadweep

Abstract

With a view to develop the oceanic pelagic fisheries, it was planned as early as 1965 to conduct exploratory fishing in the offshore and oceanic areas by drift gillnetting and purse seining. During the cruises of R. V. Varuna it was possible to plan out the operation of drift gillnet fishing which was started in January 1965 and continued as and when possible upto the end of January 1968. Purse seining for tunas was also conducted by R. V. Varuna and M. V. Tuna of the erstwhile Indo-Norwegian Project. Although during the cruises scouting for tuna was conducted by sonar (ASDIC) (horizontal range 1500 m) and echosounders, it was found that visual scouting was more effective. The characteristic sonic spires in the Deep scattering layer between 300 and 450 metre were observed and it is presumed that these could be due to the presence of larger tunas such as bigeye and possibly billfishes at that depth. A brief summary of the results of the operations has been presented earlier (Silas 1969).