Cameras, shrimps and icebergs – an eventful expedition to Greenland

The Greenland shrimp trawl fishery is in the process of applying to be certified as sustainable by the Marine Stewardship Council, a lengthy and stringent process which incorporates years of research in three themes:

1. Health of the target stock;
2. Ecosystem impacts of the fishery; and
3. Fisheries management practices. 

ZSL's Dr Chris Yesson and Dr Kirsty Kemp are carrying out part of this research in the form of a “benthic impact assessment”, which involves taking underwater photographs of the sea floor, all along the Western coast of Greenland, to determine what sea life is down there. As Chris and Kirsty’s Master’s student, I was fortunate enough to be able to travel to Greenland with them to collect the fourth year of benthic biodiversity data from the research trawler R/V Paamiut.

On 24 June we arrived in Ilulissat, the second largest town in Greenland at ~5,000 people and 2,000 sled dogs. It is a growing centre of tourism for Greenland, hosting (among other things) high end sports equipment shops and a five star hotel, yet it still retains some feeling of being an Arctic outpost. The only way to get in or out of town is to fly or sail. The houses are painted traditionally in beautiful rainbow colours, which seem to stick out in stark contrast from the harsh landscape around them. There is nothing to break the horizon on land or on the sea but ice and rocks and the high roof of the Royal Greenland seafood processing warehouse.

Chris and I were greeted on the Paamiut by a crew of Greenlandic fishermen, Danish and Greenlandic fisheries biologists, and the Faroese captain Birgir. The ship is owned by the Greenland Institute of Natural Resources (GINR), and its primary mission is to carry out shrimp stock assessments. The crew spent their days trawling and then weighing and measuring thousands of shrimp, while Chris and I took the night shift to work with our deep sea camera.

Things got off to a bit of a rocky start when on day three of the cruise, the Paamiut hit a large iceberg! The most vulnerable part of the ship was our steel sampling platform, which was crushed like a leaf against the side of the hull. The main hull of the Paamiut is ice class reinforced, so luckily the rest of the ship did not suffer much damage.

After a day making repairs in Aasiaat, we were able to continue with our (more or less) regular sampling routine. Six or seven times a night, we lowered the camera to a depth between 150 and 500 metres and take a series of 10 images of the seabed. All told, we collected around 500 seabed photographs, which is more than we had hoped for. Back in London, these images are processed to identify all benthic species (species that live on the seabed), including animals such as hydroid corals, sea spiders, brittle stars, and sea anemones.

The arctic seabed may seem like an unlikely place to find such a diversity of life, but in fact cold water coral reefs or sponge beds can be just as beautiful and almost as diverse as tropical systems in the south. This is an image of a sea pen (Octocorallia: Pennatulacea) in the genus Pennatula, taken off the Western coast of Disko Island. They are filter-feeders that live anchored in soft substrates, such as mud, and can move around the seabed in order to take advantage of faster currents. This was an exciting and rare find for us, as we have only seen four sea pens in almost 1,500 images!

By comparing the biodiversity of sites that have experienced different levels of trawling, we can start to get an understanding of how trawling is affecting the benthic marine life around Greenland. Trawling may affect different types of animals in different ways, with some being more resistant to disturbance than others. Some areas have been left to recover from trawling impacts for almost 30 years, and these may give us an idea of how long it takes for a more natural community to re-establish itself. All told, we now have about 2,400 seabed images to process and analyse. So far I have identified 44 different taxonomic groups, and I’m sure there are more to be discovered. For now, it’s back to the computer lab for me!

Until next time Greenland...

Taylor Gorham

Masters Student

Imperial College London and the Institute of Zoology, ZSL