The first dive of the Shinkai 6500 was made today with Dr. Miwa from JAMSTEC as the scientist onboard. He has collaborated with Prof. Tsukamoto on several cruises looking for spawning eels using the Hyper-Dolphin and Una-Cam drifting camera systems on the R/V Natsushima. The photo shows the submersible being deployed behind the ship, with the small boat bringing divers who will remove the connections to the ship on the top of the submersible. The dive initially went down to a depth of 1000 m and then it came up to a particular temperature range of 4.7-5.3C at depths between 800-900 m. Those temperatures and depths are based on the daytime behaviors recorded by satellite transmitting pop-up tags attached to Japanese eels. The tagged eels show very clear diel vertical migration behavior (DVM) of coming up shallower at night and then going back down deeper during the day. So we are using those depths to target our observations. The dive went smoothly, and fortunately two mesopelagic eels were seen that were using a vertical body position of holding their bodies perfectly straight and not moving. We published a paper about an eel we recorded doing that in 2012 during a deep dive of the Shinkai 6500 during that earlier cruise, so we were hoping to see some more vertical eels this time so we could publish another paper with other information in it also. So the observations today and hopefully more in the next 4 dives will enable us to make a new paper. Various other deep sea animals were seen, but no anguillid eels. The submersible also took water samples in the Niskin Bottles that were added to the outside, so that water was transferred to other containers for filtering for e-DNA or amino acid analysis. Then after dinner the Deep-Tow Camera System (YK-DT) was deployed to make video observations in the upper few hundred meters and to take water samples. Lots of interesting planktonic organisms were seen in the YK-DT video imagery until it came back onboard at 2 am, with another load of water samples.
Doctor Eel’s Logbook, Katsumi Tsukamoto, Freshwater Eel, Mariana, R/V Yokosuka, Shinkai 6500, Submersible, Deep-Tow, Research Cruise, Oceanic Survey, Spawning Behavior, Migration, Ecology, Leptocephalus, CTD, Plankton, Environmental DNA, Internal Tide, Deep Sea, Nihon University, Kindai University, The University of Tokyo, Hokkaido University, JAMSTEC
Le Blog du Docteur Anguille, Katsumi Tsukamoto, anguilles d’eau douce, R/V Yokosuka, Campagne en mer, echantillonnage oceanique, Reproduction, Migration, Ecologie, leptocephale, plankton, AND environnemental, marée interne, hautes profondeurs, Universite de Nihon, Kindai University, Universite de Tokyo, Hokkaido University, JAMSTEC