The ship used had seen similar service in 2014 and earlier to observe ESAS and Laptev seabed methane release.
Source: Siberian Times
In 2011, Semelitov was quoted as saying, "'We found more than 100 (methane) fountains, some more than a kilometre across. These are methane fields on a scale not seen before. The emissions went directly into the atmosphere..."
"This is the first time that we've found continuous, powerful and impressive seeping structures, more than 1,000 metres in diameter. It's amazing. Over a relatively small area, we found more than 100, but over a wider area, there should be thousands of them."
These methane "mega flares" previously detected were found again during July, 2014 on the SWERUS-C3 expedition which captured images of whole streams of methane bubbling to the surface, as depicted in this polar.se image.
Source: polar.se, http://earthsky.org/earth/scientists-discover-vast-methane-plumes-escaping-from-arctic-seafloor
On that expedition, the Russian professor reported 500 abnormal fields of methane emissions from the Laptev and East Siberian seabeds.
According to the Siberian Times, Semelitov revised these prior findings upward during September-October, 2016, "'The area of spread of methane mega-emissions has significantly increased in comparison with the data obtained in the period from 2011 to 2014,' he said. 'These observations may indicate that the rate of degradation of underwater permafrost has increased."
The detailed findings of the expedition were presented at an international conference in Tomsk on 21 to 24 November, 2016, however they have not been shared with the public.