During the surveys of the pelagic fish resources of the Northwestern Arabian Sea carried out with R/V "Dr. Fridtjof Nansen" during 1975-1977, mesopelagic fish were observed in abundance over wide areas. Usually the densest concentrations were found in the Gulf of Oman, in the Gulf of Aden and off Pakistan, and some trawl stations in these areas gave very high catch rates. The data from these cruises and from other available sources have been analysed by Gjøsæter (1978, 1981a), and by Gjøsæter and Kawaguchi (1980). These studies conclude that the mesopelagic stocks in the Arabean Sea is the largest known so far. An analysis carried out by Wijkstrøm (1978) concluded that a commercial fishery for mesopelagic species might be possible in these areas.
Therefore, it was decided to undertake more research in these areas, and further cruises were conducted with the R/V "Dr. Fridtjof Nansen" in the Gulf of Oman and the Gulf of Aden in July-August 1979 and in January-February 1981.
The purpose of these cruises was to make new estimates of the abundance of the mesopelagic fishes, to collect data for further studies on the ecology and life history of the species conserned, and to do experimental fishing.
Preliminary results of these cruises were reported by Gjøsæter and Myrseth (1979) and by Aglen, Gjøsæter and Tilseth (1981). Some of the data collected were also analysed by Gjøsæter (1981b).
