Tuesday, 02 September 2008

Deep trawl

This evening, we made a deep trawl on the top of a seamount, located about here. The trawl was at around 700m. The bottom was hard rock - at least, that was what we could see from the echosounder. We also used the multibeam echosounder to build up a picture of the bottom topography to look for any terrain that would be particularly harsh on the fishing gear - like pinnacles or rocky outcrops. Once we found a likely spot, we deployed the gear. Jens-Otto was somewhat concerned that we might lose the fishing gear on such an uncharted spot, but the careful survey before we did the trawl paid off. To the left, you can see Jéssica sampling some of the fairly large squaliform sharks we caught. They're not quite as big as they look there, it's a cunning camera angle trick. :)

I spent some time up in the bridge whilst the trawl was down, checking out the various control systems up there, particularly those concerned with the trawling. To the left, you can see the trawl winch control panel in the bridge. The computer screen is a readout from the winch control system, which tracks the amount of wire out, the amount of pressure being exerted on the trawl wires, the symmetry of the trawl and other useful information. On the right, you can see Øyvind Nilsen, who was kind enough to show me around the systems related to trawling on the bridge.


The nets are fitted with a fairly advanced netsonde system (Scanmar), which provides information about exactly how the net is lying in the water, particularly, how far apart the two sides of the net are (74m), how high above the sea bottom the bottom of the trawl is (rollers or "tickler chain") - you can see by the way the bottom appears to be dropping away that the trawl is actually on its way up again, and how high off the bottom the top of the net (with floats on) is. On the right, you can see the trawl coming up.

Part of Dr Fridtjof Nansen's spacious, modern and well-appointed bridge. See what I mean about tempting buttons!?






Bradley with one of the deepsea fishes we caught. I think we eventually decided this was Phosichthys argenteus.






I hear the whirling of the CTD winches, so I better go and find out what's going on as I am technically on shift now! I'll try and check in later with some more photos.

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