GfI member on expedition with the fisheries research vessel Walther Herwig III
In October/November 2013, GfI member Julian Münster spent six weeks on an expedition around the southern tip of Greenland aboard the fisheries research vessel Walther Herwig III. The purpose of this voyage was to assess cod and redfish stocks as well as other important demersal fish species in the Irminger and Labrador Seas. The results of the voyage will form the basis for future catch quotas and will be used to develop improved management and utilisation strategies.
Julian Münster reported regularly on his research and experiences on board, accompanied by impressive pictures, here in his expedition blog:
Seasickness and fulmars [Entry 1]
Icebergs off East Greenland [Entry 3]
Cod in heavy weather [Entry 4]
The Walther Herwig is a 63-metre-long stern trawler that was commissioned in 1993 and is operated by the Federal Office for Agriculture and Food (BLE). It is used to survey various fish stocks in the Atlantic, North Sea and Baltic Sea. There is room for 12 scientists and 21 crew members on board. The aim of this research trip is to investigate cod and redfish stocks off eastern, southern and western Greenland. To this end, precisely defined routes (known as lines) are fished for 30 minutes at a time. As a parasitologist at the Biodiversity and Climate Research Centre (BiK-F, a joint venture between Senckenberg and Goethe University Frankfurt am Main), my job is to examine the fish measured and weighed after hauling for parasites. This also includes further morphological and genetic identification after the trip has ended at my home institute. Research on marine parasites and their ecology provides insight into the food webs of the oceans and knowledge about the distribution of their hosts.
When I arrived on Sunday, 6 October 2013, it was still very quiet on board the FFS (fishing research vessel) Walther Herwig III, as most of the scientists did not arrive until the next day. This gave me a little time to look around Bremerhaven and familiarise myself with the ship. The first day at sea dawned with perfect weather and we set sail at around 4 p.m. on a mirror-smooth sea. I would have liked it to continue like this. Unfortunately, things turned out differently and the wind picked up quite quickly. The wind blew strongly, at times exceeding force 10, and a considerable swell quickly built up, causing the ship to dance on the waves like a cork. To mitigate the effects of these weather conditions, the captain sought shelter overnight in the lee of the Scottish coast. However, I still struggled with the onset of seasickness. But despite nausea and dizziness, and thanks to a strong stomach, I was spared the trip to the ship’s side. A patch administered by the ship’s doctor behind my ear will hopefully bring further improvement.
Today, in relatively calm seas, we were able to observe not only fulmars but also the first whales, presumably fin whales. Let’s hope it continues like this! On Sunday, we are expected to arrive in the Irminger Sea off East Greenland, our first fishing area. If the weather cooperates, fishing will begin and the quiet days on board will come to an end.
Best regards from somewhere between the Faroe Islands and Iceland,
Julian Münster
FFS Walther Herwig III in Bremerhaven
The coast of the Scottish island of Hoy
Sundown over the North Sea
(All photos: Julian Münster)
The lights of the Icelandic coast are clearly visible in the evening after sunset. We would have liked to see a little more, but even so, it is impressive.
The next morning, we arrive at the first fishing area and, after breakfast, we can begin the journey with the first haul of the planned 100. Whether we achieve our goal depends not least on the weather. In the first week of fishing, the weather remains favourable. The wind rarely exceeds force 6 and the swell remains relatively flat, so that the net can be hauled back on board up to seven times a day. The first haul usually arrives on board around 8 a.m., the last around 5.30 p.m. The codend, the end of the net where the caught fish collects, is emptied into the chute, a slide that leads to the fish deck. There, the fish is sorted by species on a conveyor belt and then weighed and measured. The otoliths, or ear bones, of the main fish species, cod (Gadus morhua) and redfish (Sebastes marinus and S. mentella), are removed through an incision in the skull. Similar to a tree, the age of the fish can be determined from the rings on the otoliths. In addition to my work in fisheries biology, I record parasitic nematodes, also known as roundworms. These are identified in Frankfurt after the expedition. The species of these nematodes are diagnosed using molecular biology, as it is very difficult to identify the different species based on morphological characteristics alone. This is particularly true for so-called sibling species, two closely related species that are morphologically identical but cannot reproduce sexually with each other or produce fertile hybrids. Parasites are usually only known for their disgust factor and as pathogens for diseases, and experience shows that their potential as indicators for ecological issues is often overlooked. The presence of a parasite usually also means that its hosts, often one or two intermediate hosts and its final hosts, are present in the region. In the case of nematodes such as Anisakis simplex (herring worm), small crustaceans are the first intermediate hosts (including Copepoda and Euphausiacea), which ingest the parasite’s eggs as food. The second intermediate hosts are small fish and cephalopods that are preyed upon by larger fish, such as cod. These are in turn eaten by the final hosts, usually whales, and more rarely seals. In these, the parasites develop into adult individuals and reach sexual maturity. The various parasite species thus provide insight into the otherwise difficult-to-access food webs of marine habitats.
Unimpressed by this, the Walther Herwig III steams towards the Greenland coast to carry out hydrographic measurements with a CTD probe at precisely defined points, determining temperature, depth, conductivity and chlorophyll content. Unfortunately, our hopes of catching a glimpse of the Greenland coast are dashed by the late hour and poor visibility. Instead of mountains, only fog and snow flurries. Only once did the coast briefly appear through the binoculars when the cloud cover lifted. In the coming weeks, however, we will be fishing closer to the coast more often and will hopefully have enough time to marvel at the fjords and glaciers.
Until then, I remain with chilly regards,
Julian Münster
Fog on the Greenland Sea
Redfish with a parasitic crustacean (Sphyrion sp.)
The fish deck on the Walther Herwig III
(All photos: Julian Münster)
After several foggy, grey days, one morning the sky is bright blue and the mainland comes into view. The coast of East Greenland is impressive; it is difficult to describe it any other way. Rugged mountains seem to rise directly out of the sea and stretch from one side of the horizon to the other. This picture is interrupted only by glaciers pushing their way into the dark sea. The mainland seems unreal and is sparsely populated. Apart from the contrails in the sky, there is no sign of human influence anywhere. The obligatory seagulls, which accompany our ship day and night in the hope of easy prey, provide the perfect backdrop.
We cannot enjoy the sun and the panorama for long, as we are not here on holiday but have a tight schedule to work through. However, the exceptionally calm weather works in our favour. The schedule takes into account days when storms make work impossible, and after a week we have almost completed twice the workload. Thanks to the continuous work and the very structured days, time flies by. Breakfast is at 7:30 in the morning, followed by a tea and coffee break at around 10:00. Lunch is ready at 11:30, followed by cake at around 15:00 and dinner at 17:30. So no one goes hungry here. We have half an hour for each meal, after which we continue sorting and measuring the fish. Longer breaks are only taken when the fishing stations are further apart or the net needs to be repaired because it has been damaged by rocks. However, everything usually runs so smoothly that we manage six to seven hauls instead of the targeted four. As a result of overfishing in previous years, the catches are also very modest, a sign that stocks have not yet recovered. This makes it all the more important to collect reliable data today in order to ensure successful fisheries management.
When the first iceberg appears, work is temporarily forgotten. The ice blocks, which lie like islands off the coast, are too fascinating. At first, there is only one in the distance. You need binoculars to see it more clearly. But over the next few days, they become more and more frequent. We enjoy the perfect view with blue skies and the panorama of the Greenland coast, but the crew on watch is less enthusiastic. Now they have to keep an eye out for icebergs and smaller ice blocks (known as ‘growlers’) day and night.
A glance at the weather report reminds us that it is usually much stormier here at this time of year. A hurricane with wind speeds of 12 has been forecast for the coming days at Cape Farewell, our current fishing area. We managed to avoid this by sailing north along the west coast. This means we can continue to enjoy calm seas with maximum wind speeds of 4.
On Saturday, the sun is shining once again and in the morning I can observe a school of pilot whales swimming in front of the ship. In the afternoon, fin whales appear and stay close to us for a long time. Most of the time, only their blow can be seen, but some individuals come close to the ship and offer an impressive sight.
If the good weather conditions continue, we will have completed all our fishing points by next week. Then, after a short stopover in Nuuk, we will begin the ten-day return journey. But there is still a little time until then.
For now, I remain with best regards from calm seas,
Julian Münster
Seagulls accompany the ship
Drifting icebergs in the grey autumn light of the Labrador Sea
(All photos: Julian Münster)
The ship is suddenly thrown to one side by a wave. All over the ship, you can hear the clattering of chairs and water crates, accompanied by the sound of breaking glass. In the corridor, an orange that has found its way out of a storeroom is enjoying its new-found freedom. Poseidon has clearly lost patience with us, or decided that we have used up our luck with the weather.
The new week actually began once again with outrageously good weather. We also noticed very little of the hurricane passing close by; in fact, the only sign was the drop in the barometer. So we continue to make very rapid progress with our programme. The catches off the west coast of Greenland differ significantly from those off the east coast. While the codend on the east side arrives on board well filled, here in the west it is often only a handful of fish. The reason is probably the heavier fishing in the Labrador Sea. On both sides, redfish (Sebastes marinus, S. mentella) and cod (Gadus morhua) are the dominant species. Cod in particular plays a crucial role in the food webs, filling some ecological niches and displacing other species. Predators, especially for adult animals, are rare. Cod stocks maintain their own balance through cannibalism. In the less heavily fished east, where fishing is banned in some regions, fish of all sizes can be caught, while in the west, fish are usually no larger than 50 cm, with no specimens over 100 cm at all. It is difficult to imagine whether cod stocks will ever return to their former strength. This species is a good example of uncontrolled exploitation. It has been targeted by fishermen since the beginning of the 16th century and has become increasingly important. Stocks reached their economic peak in 1968 with a total catch of over 3.9 million tonnes. The economic importance of cod was evident in the dispute over territorial waters and associated fishing regulations, which escalated into the three so-called ‘Cod Wars’ between Iceland and Great Britain, in which Germany was also involved.
The peak in 1968 was followed by a collapse in stocks due to overfishing and a prolonged cold spell. Today, catch quotas are strictly regulated. For 2012, the TAC (Total Allowable Catches) was set at 810,031 tonnes. Despite the sharp decline, cod is still among the top 10 most intensively fished marine species worldwide. In 2012, both the EU and NAFO (North Atlantic Fisheries Organisation) imposed a fishing ban on certain regions off south-west and south-east Greenland.
Thanks to the good weather, we have no days lost and are able to work through all the fishing points 10 days faster than planned. On Friday morning, we sail into Nuuk’s Godthab Fjord as the sun rises impressively. Here, the traces of autumn have already disappeared under a thin blanket of snow. Only the relatively warm sun and the Inuit, some of whom are lightly dressed, show that winter has not yet arrived. Nuuk is a loose collection of colourful wooden houses interspersed with some dilapidated prefabricated buildings. In the city centre there is a modern shopping and social centre. Overall, the capital of Greenland, with its approximately 17,000 inhabitants, is a nice small town situated in a wonderful fjord landscape. The surrounding mountains look a little like the Alps. Countless small and large icebergs and growlers float on the calm fjord, some of which are washed up on the small bays at high tide. At night, the scenery is illuminated by greenish northern lights. How fortunate that the sky is clear enough for long enough to take a few photos before the next morning’s fog turns everything black and white.
Unfortunately, we have to leave earlier than planned because the weather forecast predicts another storm. The cloud formations as we set sail do not bode well; this time we cannot avoid the low pressure system and sail straight into it. The sea remains calm until Cape Farewell, but as soon as we leave the shelter of the coast, a considerable swell quickly builds up. The wind and waves from astern, together with the swell coming through the Denmark Strait, cause the ship to rock violently, sending everything that is not lashed down or safely stowed in cupboards flying through the ship. It is a little frightening when the ship is in a trough and suddenly wave crests tower above you where they shouldn’t be. The ship is thrown from side to side, it is exhausting to stay on your feet, and in bed you have to hold on to avoid rolling out. Eating is difficult in these conditions.
In the harbour of Nuuk
View over the capital of Greenland
Polar lights
Godthab-Fjord
(All photos: Julian Münster)