A deep sea octopod, one of the first animals captured on the second leg
An eel larvae. Photo: D. Shale
CTD sampling rossette entering the waters above the MAR. Photo: D. Shale
Date:7 July 2004
Author: Aino Hosia (Univ. Bergen, Norway), Monty Priede (Univ. Aberdeen, Scotland)
Today's absolute highlight must have been the first station of the second leg. With mostly new scientists onboard, everyone is excited about getting a glimpse of what lives in the depths of the Mid-Atlantic. A major feature of the second leg is direct underwater observations of living deep sea animals in their natural environment using cameras on board ROVs (remotely operated vehicles) and landers. As we approached Superstation 40, our first stop out of Horta, the Aberdeen team were preparing the ROBIO lander for launching. The ship circled round while the captain examined the sea floor looking for a likely landing site for ROBIO, in the foothills of the western side of the MAR.
Once the position was agreed, the ROBIO was launched into the deep by the light of the ship’s flood lights. The floats were slipped down the trawl ramp at the stern of the ship and the lander itself was lifted into the water by crane. Like all deep sea landers ROBIO free-falls to the sea floor, taking about 70 minutes for the journey in 2600m of water. ROBIO carries a digital camera, and sensors for current, depth, temperature and salinity, all of which are logged on an on board computer.
With ROBIO away doing its work, precious ship time was not to be wasted. A CTD and an underwater video profiler were employed to look at the water column and then the sea floor was mapped in detail using the SIMRAD EM300 multibeam echosounder to determine a good track for trawling where the net would not get snagged.
On board we have two ROVs for mapping the deep ocean fauna. The tried and tested Aglantha, operating down to 2000 meters, and the brand new Bathysaurus with an amazing maximum operational depth of 5 kilometers. The plan is to employ an ROV at each station to film, and sample, the deep-sea organisms living at the Mid-Atlantic Ridge. As the technicians were still working on preparations, the ROVs were given a rest while we got down to some serious fishing.
The trawl was deployed on the bottom at 2900 m and 4 hours later everyone came out on deck to watch the catch come to the surface. As the net came on board a deep sea grenadier fish was spotted in one of the wings and once the net was opened, Mike Vecchionne quickly retrieved a large deep sea cirrhate octopus. It was a field day for the new scientists onboard, who immediately dug into the pailfuls of animals in search of their favourite critter. Apart from many species of vicious-looking fish with rather long, sharp teeth, several bucketfuls of large sea cucumbers resembling slimy violet footballs were brought up by the trawl. Sorting the species in the fish room was a challenge, such variety is not normally seen in shallow water fisheries.
MS Loran is working southeast of us, on the eastern flank of the mid-Atlantic Ridge, and have already finished a number of longline trials resulting in large catches of the deep-sea rattail Coryphaenoides armatus and many other species, including a number of deep-sea sharks. Communication with the vessel is currently easy via e-mail, and pictures are exchanged for identification.
On board the G.O.SARS the day ended as it began, mapping the sea floor. This really is exploring, there is no point in us capturing or observing animals unless we know where the observations came from. We are laying the foundations for future voyagers to this fascinating part of the ocean.
Report from MS Loran, by Inge Fossen, Chip Cotton, Jan Erik Dyb & Ann Helen Hellevik
We steamed out of Horta on the evening of July 4th and arrived at the first station early on the morning of July 6th. During the trip we enjoyed gorgeous weather, calm seas, dolphin-watching, whale-watching (sperm whales and some unidentified whales), sea turtle sighting and freshly cooked waffles on the bow of the boat. Once the work began, these happy times were sorely missed as the scientists have been working 16-hour shifts in order to keep up with the fishermen. The M/S Loran is a highly efficient and automated vessel. The crew has been extremely patient and helpful in getting this research done. Hook baiting, setting, and hook retrieval is almost an entirely automated process and it is truly a wonder to see in action.
So far we have sampled 7 stations, three with the longline and one with a gillnet. The longline stations have been fished on the bottom in approximately 2500-3000 meters of water, with approximately 3000 hooks per set. The gillnet was fished on the bottom in the same depth stratum but only yielded one fish. These first stations have yielded at least 18 species, including rattails, gulper sharks, lantern sharks, Portuguese dogfish, chimaeras, slickheads, deep-sea eels, deep-sea rays, various deep-sea cod-like fishes, and little sleeper sharks. We are researching the possibility that several of these fishes are very rare species. Stay tuned for the results on that investigation…