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"G.O. Sars" arrived in Walvis Bay, Namibia

The research cruise with G.O.Sars in the Southern Ocean has come to an end. We were safely guided to the harbour in Walvis Bay by our navigators, together with the pilot onboard the boat “Flamingo”.

Above:
The patrol vessel “Flamingo” besides G.O.Sars. Photo: Leif Nøttestad

Cape fur seals also joined us the last mile into the harbour. After more than 5 weeks at sea without being on land, it feels strange to put our feet on solid ground in Namibia. When we start walking on land our legs feel a bit shaky. The body is used to the movements of the ship in the Southern Ocean caused by everything from moderate wind to stormy weather.

The participants in the second leg of this cruise have worked hard on the cruise report prior to reaching the harbour in Walvis Bay. It is always best to finish reports while onboard, before we spread all over the world. The cruise report should be useful and interesting reading for both scientists and laymen.


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Cape fur seals following us into the harbour. Photo: Eirik Grønningsæter


We have collected Terrabytes of data from an vast collection of instruments and sampling devices onboard. From our main results, we have estimated the amount of Antarctic krill (Euphausia superba) to be approximately 14 million tons, within an area covering about 500 000 km2. This number is most likely an underestimation, due to the fact that we have not counted the krill appearing and swimming close to the surface. The reason is that the echosounder which we primarily use to estimate krill along the cruise tracks, do not detect schools (less than 15 m depths) close to the surface.


Scientific personnel and crew on board G.O. Sars during 2 Leg of the AKES cruise. Photo: Elise Golten

 

The quantitative multibeam sonar, on the other hand, is able to detect krill schools all the way up to the surface, and has thus been an important complementary scientific acoustic instrument in the Southern Ocean. The ocean areas we have mapped and applied in the abundance estimation only include about 5% of the Southern Ocean. This shows how large ocean area we are talking about north of the Antarctic continent. If we are assuming a uniform distribution of krill around the Southern Ocean, the total estimate is then roughly 280 million tons of krill. The scientific AKES cruise on board “G.O.Sars” has definitely increased our knowledge about Antarctic krill and the Southern Ocean ecosystem.

 

There have been 41 people on board “G.O.Sars” during this 2 Leg of the AKES cruise, and we would like to thank all for their contributions and hard work!
 

Written by

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Leif Nøttestad, PhD, senior scientist at the Institute of Marine Research in Norway, working on behaviour, ecology and management of herring, mackerel and bluefin tuna. Leif is on this expedition involved in studies of fish and marine mammals, sonar investigations of krill and public outreach work on film and photo on board G.O.Sars in the Southern Ocean.