Summary report on cruise of the R/V Shoyo Maru in the north Arabian Sea, 2 October 1976 - 13 January 1977
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At the Fifth session of the IOFC Executive Committee held in Rome in April 1976, the Indian Ocean Programme reported its success in bringing the R/V Shoyo Maru to the Arabian Sea and adjacent waters off India and Pakistan in November and December 1976. The present paper gives a brief description of the survey and its results, summarized from the original report in Japanese which will be published by the Fishery Agency of Japan in 1977. The activities covered oceanographic observation, convention al biological survey (sighting of pelagic shoals and collection of fishes) and acoustic survey. In spite of special attention, the squid Sympleototeuthis oualaniensis did not appear abundantly during the present cruise. The equatorial undercurrent did not exist in the equatorial waters during the transitional period, from the southwest monsoon to the northeast monsoon. Although the upwelling was recognized in the western part of the Second Area in the 1975 cruise, this was not encountered in the 1976 cruise. This might be attributed to the difference in the survey period; the first cruise in 1975 covered the late southwest monsoon season while the present cruise the early northeast monsoon season. The coastal upwelling on the continental slope was evidently less remarkable during the present cruise than during the previous one. The pelagic shoals again appeared rather scarce in the offshore waters throughout the survey period as was the previous cruise. There was a considerable number of important commercial fishes, almost the same species of the previous survey, on the Pakistani continental shelf, but none of them appeared to be large enough to attract a large-scale operation. In the present survey, the squids were not caught as often as in the previous survey. The index of echo abundance in the Second Area in 1976 was half of that in 1975. Since the duration of our cruise was very limited, it was difficult to find any reasoning for such year-to-year variation. However, it might be suggested that the squids moved toward the west coast of India or the southern Arabian Peninsula, or a deeper layer during the northeast monsoon season.