Blog: Whales predict the catch of krill under sea ice

Photo: Jan and Fokje are having a look at the SUIT catch. The pink-orange colour shows that there is a lot of krill.

In the last loose sea ice we had the opportunity to fish with the SUIT and the RMT. We were very happy with this, since we haven’t been fishing under the ice a lot due to the lost time and our new route.

Whales predict the catch

The many whales that had been spotted and the brown discolouration at the underside of the ice made us suspect that there might be a lot of krill in the area. Krill is an important food source for whales. Additionally, the brown colour of the ice indicates that there are a lot of algae growing in it, which are an important food source for the krill. And indeed, after counting the catch of our first fishing attempt close to the ice edge, it turned out that we caught over 6000 krill. More than enough to take samples to analyse at home, for instance to look at stomach content or measure the energy value. Apart from krill, there were also a lot of amphipods in our net, another crustacean species that we frequently encountered on this journey. The next fishing attempt in the ice edge even exceeded the first one and yielded more than 11.000 krill.

Collecting the last ice core

During the ice stations we collected ice cores. The cores were left to melt slowly in the ‘cold container’, our chilled working space. The work area is kept cool to ensure that the temperature difference with outside is not too big. After the cores had melted, we put the remaining water over a fine mesh filter. Algae and other in-ice life will remain on the filters, which we also will take home for further analysis. There were many hours spent in this working space. Since the last ice core has now been melted and processed, the cold container is now also ice free.

Last time ice fishing with the SUIT

This week we fished with the SUIT for the last time in open water. Although we found it a bit sad that it was the last, it is time to start packing and preparing for the way home.

Fokje Schaafsma, 21 January 2015

Southern Ocean, 60.14°South – 00.12°West