Results of the Royal Society Indian Ocean Deep Slope Fishing Expedition, 1969

During a 6-week Royal Society Expedition in the western Indian Ocean 638 fishes were caught on drop lines worked chiefly at night at depths between 100 and 1000 m. Many of the species caught were rare or unrecorded from the area. The primary aim of the Expedition, to find specimens of the coelacanth Latimeria and thereby extend its known range, was not fulfilled. One teleost, the lutianid Etelis marshi, and a squaloid shark, Centrophorus sp., were particularly common, accounting for 60 % of the total catch; the remainder comprised 24 teleost and 11 elasmobranch species. Details are given of the itinerary, the fishing gear, fishing methods and the individual species caught, together with a brief discussion on the effect of depth, height of hooks above the sea floor and geographical position on the composition of the catches.