Summary lectures Sea Mammal Days (Saturday 23-2-2019)

The lecture program of the Zeezoogdierdagen 2019 was held at NIOZ and was opened by Henk van der Veer (Head Dept Coastal Systems, NIOZ). He gave a very brief introduction about the history of NIOZ and showed a short movie about the research activities of the institute. The day was chaired by Geert Hoogerduijn, team leader Wadden Unit (Ministry of Agriculture, Nature and Food Quality) and coordinator of stranded cetaceans in the Netherlands.

Chair of the day Geert Hoogerduijn (ministery of LNV) welcomes the public
Chair of the day Geert Hoogerduijn welcomes the public

10:45 – 11:15  Anne-Marie Svoboda (Ministry of Agriculture, Nature and Food Quality)

Working on cetacean issues at the Ministry

Anne-Marie Svoboda introduces herself as a marine biologist, which is now working at the ministry. She gave an overview of all Dutch ministries dealing with subjects on marine nature. Cetacean policy at the Ministry of Agriculture, Nature and Food Quality includes various projects such as the harbour porpoise protection plan, of which a second edition is expected in 2019. In collaboration with fisherman interesting results were obtained during 5 year’s monitoring of incidental bycatch of harbour porpoise. Also, the ministry is dealing with international treaties such as ASCOBANS, OSPAR, bird habitat directive (EU BHD) and Marine Strategy Framework Directive (EU MSFD), International Whaling Commission (IWC).

The MSFD focuses on biodiversity, litter and noise and started in 2012, and will follow a six-yearly cycle. (More information about the MSFD and cetaceans can be found on and Underwater noise generated e.g. by sonar, seismic activities, construction/drilling, explosives and drilling is an issue since 2004, but recently the MSFD has defined noise as pollution. More information about the MSFD and cetaceans can be found on the and

IWC is an organisation with 89 member states all over the world, which is committed to the conservation of whales and management on whaling. Some member states object to the whaling management as laid down in the moratorium of 1982, and still hunt whales in their own waters, for scientific purposes, or practices aboriginal subsistence whaling. For management bodies, it can be hard to reach agreement on the different view of international whaling. Recently, in December 2018 Japan decided to leave the IWC as member state. It is not clear which effects this will have for whales and whaling.

Since the mass stranding events of sperm whales in 2016 in North Sea, protocols were set up to regulate these events, including the euthanasia and post mortal research. Geert Hoogerduijn, is appointed as coordinator the strandings of large whales and will evaluate the activities during and after the stranding. Post-mortal research on stranded whales include pathobiology, diet, contaminants, plastics, hearing damage, which is done by various institutes in the Netherlands.

Anne-Marie Svoboda (Ministery of LNV) talking with Sophier Brasseur and Jan Beiboer
Anne-Marie Svoboda (Ministery of LNV) talking with Sophie Brasseur and Jan Beiboer

10:45 – 11:15  Anja Reckendorf  (Tierärtzliche Hochschule, Hannover – Germany)

Marine debris and plastic pollution – an emerging threat to aquatic wildlife and human health

Anja Reckendorf is researcher at the institute for Terrestrial and Aquatic Wildlife Research in Büsum, Germany. In her presentation she gave an overview of the emerging threat of marine debris on wildlife and human health and presented some results of ITAW.

Marine debris can be defined as “any persistent, manufactured or processes solid material discarded, disposed of or abandoned in the marine and coastal environment.” It can be found anywhere in the marine environment (beach, water surface, ocean floor etc) and is moved by currents, wind and waves. In some cases, marine debris is directly dumped in the ocean, for instance by cruise ships, but by far the largest proportion of marine debris originates from rivers. In total 94 per cent of marine debris enters the oceans by rivers. In 2010 this was estimated to be 275 million metric tonnes. 

Marine debris can break down by sunlight (UV), waves and wind, salinity and temperature. The rate of degradation can be categorized by the size of the marine debris, which ranges from mega debris (>100mm) to micro debris (<5mm). These particles can also absorb chemical pollution. An important problem is that (micro-)plastics are ingested and accumulate in the food chain. It has been shown that 56% of cetaceans ingest marine debris.

At the ITAW, the research on plastic pollution has three divisions: distribution of floating debris, macro plastics on animals and macro plastics inside animals. In a recent study they examined records of 1622 harbour porpoises, harbour seals and grey seals between 1990 and 2014 along the German coasts. These records revealed 14 entanglements and 17 cases of debris ingestion and detected objects comprised fishing-related debris (64.9%) as well as general debris (35.1%). Furthermore, in another study a large amount of marine debris (250 fishing-related items and 72 pieces of general debris) was found in nine out of 22 sperm whales that stranded along the North Sea coast in early 2016. Both studies show the evidently high level of marine mammal exposure to marine debris and the imminent threat of associated health and welfare risks within the German North and Baltic Sea. Various larger items found in sperm whales, such as a 68×23.5 cm plastic engine cover of a car. It was concluded that the marine debris was not the cause of the death in these animals, but the larger particles may have fatal consequences in later life.

The conclusion of the presentation was that plastic pollution is an emerging non-infectious threat to aquatic wildlife and human health. It is possible however to have a positive influence yourself. It is possible to join organisations that work on reducing plastic waste and to use less plastic yourself.

Anja Tierärtzlicht Hochschule, Büsum) shows a plastic engine cover found inside a sperm whale's stomach.
Anja shows a plastic engine cover found inside a sperm whale’s stomach.

11:45 – 12:15  Annabel Kok replacing Fleur Visser(NIOZ / University of Amsterdam)

Foraging in a noisy world

Annabel Kok is a PhD student with Fleur Visser and both are studying the effect of sound on marine life. The continuing rise in underwater sound levels in the oceans, such as for example pile-driving and shipping, leads to disturbance of marine life. Sound seems to be one of the reasons of cetacean standings, but sound may also cause other less visible effects. It could also cause changes in the foraging behaviour of marine species, for example by deterring animals from a suitable prey location or by distracting them while they are trying to catch prey. Underwater sounds are increasing due to an increase of anthropogenic activities, for example. Many living marine creatures depend on sound for various purposes such as navigation, echolocation or communication.

The research of Fleur and Annabel focuses on the predator-prey interaction changes due to sound, with fin whales and Risso’s dolphins as predator species. Animals are equipped with suction cup-attached archival tags (D-tags), which included a hydrometer, accelerometer and pressure sensor. For fin whales also cameras are used on the animal. Echo is used to monitor the prey species of both study species. Annabel showed various 3D animations how dolphins reacted on sound. One of the preliminary results is a change in the behaviour of Risso’s dolphins in the way they response to underwater sound. The sound that Risso’s dolphins generally produce near the water surface, are now recorded at much greater depths, where it is getting noisier. The aim for the coming years is to gain more knowledge if and how sound can affect the ability of cetacean foraging and how it might effect the balance of marine food chains.

Annebelle Kok - Universiteit Leiden
Annebelle talking on cetaceans in a noisy world

12:15 – 13:45 Lunch break

Lunch prepared by StayOkay-Texelat Zeezoogdierdagen 2019
Lunch at Zeezoogdierdagen

13:45 – 14:15  Eleonora Panella  (IFAW, Brussels- Belgium)

Whales and ship strikes. A case study in the Mediterranean.

Eleonora Panella is a marine biologist and works as a wildlife campaigner for the IFAW (International Fund for Animal Welfare) in Brussels. She presented work of IFAW that has been done to prevent ship strikes in the Mediterranean Sea.

Eleonora Panella (IFAW-Brussels) talking on ship strikes in the Strait of Gibraltar
Eleonora talking on ship strikes in the Strait of Gibraltar

Marine mammals face many anthropogenic threats. These include entanglement, climate change, habitat loss, noise pollution and ship strikes. Noise pollution and ship strikes are a major threat to cetaceans. Underwater noise causes chronic stress, affecting many individuals, but ship strikes affect far fewer individuals but cause serious injury and death. If vessels slow down, both noise pollution and ship strikes will be reduced.

The Strait of Gibraltar is an area with a high shipping density and a high occurrence of marine mammals. Therefore, this can be seen as a high-risk area. In 2007, a part of the Strait was defined as a zone where a reduction of speed to 13 knots was recommended. Three years later, a survey was done about the speed limit and it turned out that most skippers did not know about it and most vessels had a much higher speed in the defined area. Fast ferries were the fastest, with speeds up to over 30 knots, normal ferries mostly sailed between 13-19 knots, and cargo ships on average around 10-15 knots.

The pilot whale is a very well-studied species in the Strait of Gibraltar. These whales seem less affected by ship strikes, but he construction of the port of Tanger may have had negative effects. Various ferry routes are crossing their main distribution area. Pilot whales are the most abundant species and therefore the main target species for whale watching in the area, which causes pressure on these animals.

It was concluded that not much is known about the ship strikes on large whales, but there are many signs of smaller vessels in collisions with smaller cetaceans. There is no protocol in place to report ship strikes in the Strait of Gibraltar, and speed limit is not implemented. The IFAW recommends the slowing down of vessels. This not only reduces noise pollution and the risk of collisions, but also reduces fuel consumption. Other causes of distress include, small vessels, whale watching, plastic pollution and epizootic episodes.

14:15 – 14:45  Meike Scheidat  (Wageningen Marine Research)

The International Whaling Commission (IWC) – defining a new role in global whale conservation and management.

Meike is marine ecologist gave an short overview about global conservation policy and politics of cetacean conservation, with special emphasis on the IWC (International Whaling Commission).

The major developments in the modern commercial whaling started around 1860, when the harpoon and faster (steamed) vessels were introduced. This resulted in a higher catch, which reduced the number of whales considerably. After the World War II, the ICRW (International Convention for the Regulation of Whaling) was set up in 1946 and the IWC in 1949. Sixteen member states (including the Netherlands) of the IWC agreed in 1950 on a proper conservation and an orderly development of the whaling industry. The industrial whaling killed nearly 2,9 million whales of various species in the twentieth century. Most whaling occurred in the Antarctic, but around 1960 whaling was rapidly increasing in the Arctic. At that time scientific advice was little used and based on poor data.

During the 1960s there was more open and liberal society and this was the time when new norms developed about whales and whaling. These include humane killing of whales and the idea that whales are conscious intelligent beings and nature conservation in general. This led to quick conservational changes for the great whales, such as bans on hunting of some species or establishing quotas for other species. In 1982, the whaling moratorium was decided and became effective in 1986. This decision stopped commercial whaling, however this was objected by a number of states including Norway, Japan, Peru and Iceland.

The Convention talks about management of whales, but what exactly is a whale? Anyhow, small cetaceans were mostly ignored by the IWC. Therefore, a sub-committee on small cetaceans was established in 1979 and finally in 2009 a research fund for Small Cetacean Conservation was set up by IWC. In 2014 small cetaceans were officially included in the work programme of the IWC. This is good news because some small cetaceans are really in trouble (and have no other international governmental body responsible for their conservation and management).

At the eind of her talk, Meike sketched two possible ways the IWC could develop from now on. This is particularly interesting as Japan resigned as a member state from the IWC in December 2018. One way could be that Japan start whaling in Japanese waters, other countries resign from IWC and also commence commercial whaling.Another way is more positive: the South Atlantic Ocean Sanctuary will be established, the special permit whaling will stop and the IWC will start protecting the small cetaceans. The IWC could redefine its mandate and become very effective tool to help address the most pressing threats (maybe noise pollution or shipping strike is more relevant) to all cetacean species globally.

Meike (WUR IJmuiden) talking on issues in IWC
Meike talking on issues in IWC

14:45 – 15:15  Nathalie Houtman (WWF-NL, Zeist)

International Cetacean Conservation by WWF

Nathalie Houtman works for the WWF. She currently is on an assignment where she studies underwater noise, plastic and human-animal interactions. In her talk she presents the work that the WWF does in regards to international cetacean protection.

The WWF is involved with cetacean protection since 1961, and regards cetaceans as priority species. By-catch, shipping and habitat degradation are the three main threats globally. With efforts of organisations like WWF nature conservation can work. Nathalie explains with several case studies how the WWF works and tries to improve these 3 threats.

The vaquita is currently the most endangered cetacean species. The current vaquita population estimate is 18 adults. It is heavily threatened by entanglement in the nets used by illegal fisheries in the Gulf of California. The gillnet fisheries target the endangered totoaba, of which the swim bladder can pay as much as 10000 dollars on the Chinese market. The goal of the WWF is to create a gillnet-free habitat, which is done in several ways such as lobbying, enforcement, searching for alternatives and research. The protection work for the vaquita is a joint-effort with many organisations and institutions. Despite the low number of adults, there is still some hope for the vaquita: recently 2 young vaquitas were spotted. This could make a population recovery possible.

An other examples are the Indus river dolphin and the right whale, which also suffer from the threat of entanglement. The WWF is trying in improving the protection of these species by looking for alternatives, doing research and international collaboration. Entanglement is the biggest threat to marine mammals, but it is also costly for fishermen because their gear gets damaged or lost.

Shipping is a never-ending stream of traffic in the marine environment causing noise pollution and collisions with cetaceans. It is a big threat, and mainly large cetaceans are affected. The WWF is looking for alternative shipping routes, doing research on early warning tools to avoid ship collisions (REPCET), collaborating with other organisations and working on engagement.

Habitat degradation is caused by oil and gas industries and other human activities. One solution to stop habitat degradation is the protection of certain areas and to create safe havens where cetaceans can feed, breed, socialize and migrate.  In the arctic, the goal of the WWF is to have 30 percent of the area protected. In 2016, 5 percent of the arctic was protected. It is likely that the willingness to protect the area will increase because of the climate change and the decreasing sea ice.

At the end of her presentation Nathalie shows us how we can help. We can sign the petition to protect the Arctic on and help protect the cetaceans and other marine life in the Arctic.

Nathalie Houtman talking about cetacean conservation projects of WWF
Nathalie talking about cetacean conservation projects of WWF

15:45 – 16:15  Geert Aarts & Sophie Brasseur (Wageningen Marine Research / NIOZ)

Opportunistic sound exposure experiments: Behavioural reactions of wild grey seals to pile-driving.

Geert Aarts is a marine biologist, specialised in predicting how marine mammals are distributed in their environment. He also studies the effect of underwater noise on porpoises and seals. He presented his work on the behavioural response of grey seals to pile-driving.

The hearing of seals is best at low frequencies. The frequencies that are emitted during pile driving are between 0.5-1khz, which is within the range of what seals can hear. To study the effect of pile driving on grey seals an uncontrolled outdoor ‘experiment’ was done, with several seals that where tagged beforehand with GPS-trackers and time-depth recorders. The behavioural responses of seals were recorded as well the distance to pile-driving activities in two offshore wind farms in the North Sea in 2015.

Geert Aarts (Wageningen Marine Research) shows how seals react on noise wind parks
Geert shows how seals react to noise in wind parks

There was much variability in behavioural responses between individuals, such as changes in dive patterns, how fast the seals were descending to the bottom, changes in the direction of swimming or no change in the behaviour at all. The distance to the pile-driving activity appeared not always a good predictor for the reactions of the seal: there were seals no apparent response at small distances (e.g. 12km) and seals further away (37 km or more) that reacted clearly on the noise of the pile-driving. From the behavioural is assumed that the seals do not know the direction of sound and thus do not know where sounds of the pile-driving come from.

Future plans of this study include the improvement of the statistical methodology, the change the behaviour state of each seal and to use more detailed 3D movement data that were collected with the loggers. It is also planned to study the effects of mitigation efforts of pile driving.

16:15 – 16:45  Kees Camphuysen (NIOZ)

Cetaceans as an integral part of marine ecosystems: towards a better understanding of distribution patterns and temporal trends within the North Sea basin.

Cees is a marine ecologist working for NIOZ. In his presentation he discusses how research on cetaceans could be more integrated in ecological studies. Historical research on cetaceans had limited or no interest in the ecology. Old publications mainly focused on the occurrences, abnormalities, rarities, mainly on stranded animals or striking observations. Today more advanced research is conducted which is partly facilitated by the electronic revolution. We can now study the hearing ability of an animal in a captive facility (as already done by Dudok van Heel in the 1950s at NIOZ) or using tracking devices in the wild. Using advanced software, we are able to create complex models, for instance predictive habitat models.

Nevertheless, real ecological studies seem to be lagging behind. In other words, the reasons why certain trends occur are not clear. Cees showed us various studies of species that are decreasing or increasing over time and space. Examples are harbour porpoises in the southern North Sea, the changing composition of different dolphin species on the Dutch coast and other studies elsewhere. Scientists generally don’t have any clue why this happens or why animals use certain areas. People in the field who are out for monitoring a specific species, might not be as open for other factors that may be very important. We should spend more time in the field then behind the computer to observe what is really happening out there. For pro-activemanagement of marine ecosystems, it is really important to identify which species are at risk and which habitats are critical for conservation.

Studying the marine ecosystems, such as the North Sea, has opportunities but also constrains. Some variables are easy to measure, but might be ecologically less important. If you use an explanatory factor such as chlorophyll a to estimate the distribution of marine mammals, you are skipping many steps in the food chain. If you take the length of the food chain into account, you might realize the relation between the two variables is probably nonsense. The same holds true for variables such as sea surface temperature (SST) and bathymetry thresholds. For instance, data on vertical migration and the availability of prey, or the behaviour of prey and predators may not be as easy to obtain, but more likely to be relevant. We should try to understand the ecosystem using a multi-species approach (with predators, competitors, facilitators), and not limit us only one species.

Kees Camphuysen (NIOZ) on the charismatic megafauna in the North Sea
Kees on the charismatic megafauna in the North Sea

16:45 – 17:00 Workgroup Marine Mammals and concluding remarks by the chair. 

The day was closed by a short presentation of Workgroup Marine Mammals how we, as a work group, can contribute to marine mammal issues. In 2018 the work group was present at a symposium on underwater noise and the shipping industry, organized by IFAW, ‘Stichting De Noordzee’ and ‘Rijkswaterstaat’. This symposium brought together all parties involved, such as industry, policy-makers, government and other stakeholders, to learn from each other and talk about possible solutions. It became clear that the industry is willing to work on solutions, but that there is often no clear definition of the problem or the goals that should be achieved. For example: when does underwater sound become noise? The workgroup might be able to play a role in these ‘translations’ as we are not specialists but generalists.
The work group also participated in a meeting about ‘Natura 2000’ areas in the Dutch part of in the North Sea. Rijkswaterstaat invited stakeholders to provide input for the management plans for these three protected areas in the North Sea. An important comment of the workgroup on the proper assessment was that scientific information on English seals is not included for the Dutch part of the Doggersbank. The English coast is closer to this part of the Doggersbank and it is likely that especially English seals are foraging or hanging out in this area.
Finally we also think we can play a role in citizen science. For example, in the goody bag of the Zeezoogdierdagen there is a flyer from, named Sex on the beach. It containes some simple guidelines to increase the significance of each observation of stranded dead harbour porpoises. If also length and sex can be determined from these records then this information is very valuable for researchers like Lonneke IJsseldijk and Mardik Leopold.
This means there is a lot to do for the work group. Inge invites attendees interested in participating in the work group, to contact us, as well if someone has an idea on what else the work group could do.

Finally, the chair thanked the presenters of the talks, the team of volunteers and all attendees.

Speakers and volunteers of the Zeezoogdierdagen2019
Speakers and volunteers of the Zeezoogdierdagen2019

Many thanks to the reporters Jessica Schop and Ronald Smit for the summaries of the talks!