The Seamounts Cruise Gets Going

After a very pleasant day or two at Cape Town RRS James Cook sailed at 14.00 on Monday 7^th November. It was a beautiful sunny day and the ship moved smoothly out of the Waterfront harbour and out to sea. We all stood on the foredeck taking photographs of Table Mountain as the ship swung to the east to take up the first station. Cape fur seals were lying in rafts dotted here and there and would lazily swim off or suddenly dive as the vessel approached. Cape gulls drifted past and gannets flew low over the water passing by without heed to the ship. We made a stop and deployed the CTD (Conductivity, Temperature, Depth), a large metal frame with water sampling bottles and instruments for measuring temperature, oxygen concentration and fluorescence (chlorophyll) in the water column. After this it was time to calibrate the multifrequency echosounders we use to look at the behaviour of the animals living in the water column during the trip. This was a very fiddly operation requiring the suspension of a small metal sphere underneath the hull-mounted echosounders of the ship using a combination of three lines deployed from what resembled fishing rods over the side of the ship. We had heard horror stories about how long this operation could take but we were very lucky with calm weather and immediately managed to get echoes from the sphere. Outside fur seals swam around the ship. They were very sociable, often gathering in small groups, prodding each other with their noses or scratching or grooming themselves with teeth or flippers. Occassionally one would hang, tail up out of the water and head down on the surface. At one point out metal sphere and lines suddenly moved back towards the stern of the ship and we were quite suspicious that the seal’s curiosity had got the better of them and they had come to investigate our calibration sphere. We could see the seals diving on the echosounders as they were blowing trails of bubbles as they dived down to 70 or 80 meters below the ship, occasionally coming up chasing small fish (we had seen a large male trap some fish between the harbour wall and the ship while it was moored in Cape Town and then proceed to gorge itself for half an hour or more). The whole operation was completed by 02.00 on Tuesday morning, much quicker than we were expecting, at which point we recommenced our journey towards the first seamount, Coral. The moon appeared between clouds and the ships wake was bright blue green with bioluminescence, an amazing sight.