Yearly stranding reports

As part of the implementation of the Royal Decree on marine species protection in the Belgian national waters, the institute produces annual reports on observations and strandings of marine mammals in Belgium. These reports are available in Dutch and French on this web page (previous reports only in Dutch). Printed copies can be requested at marinemammals@naturalsciences.be.

Report of 2019

The Royal Belgian Institute of Natural Sciences (RBINS) has been responsible for coordinating research into the strandings and cause of death of marine mammals in Belgium since the early 1990s. Information on observations at sea is also collected. With the collaboration of SEALIFE Blankenberge and the Universities of Liège and Ghent, RBINS has, as it does every year, brought together the available data in a report.

In 2019 51 harbour porpoises washed ashore: a low number compared to previous years. More than half of these animals were in a far state of decomposition, and often the cause of death could no longer be determined. Four porpoises had ended their lives as bycatch, four others as a result of predation by a grey seal. The estimated density of harbour porpoises at sea in June and August was about the average of previous years. The only other cetacean found stranded was a highly decomposed common dolphin. As in 2018, a solitary, social bottlenose dolphin was present for months in the area bordering French waters. In addition, a group of bottlenose dolphins was observed twice. More exceptional were the sightings of a humpback and a minke whale.

The presence of seals on our coast is still on the rise; in the port of Nieuwpoort there is now a permanent resting place which is often used by more than 10 harbour seals. Grey seals also seem to be becoming more common. This translates into increasing numbers of dead and dying seals on the beach: 47, the highest number ever recorded. SeaLife took care of 11 Grey and 15 Common Seals.

In 2019, two leatherback turtles and some sunfish were observed. Their presence was possibly related to an unusual influx of Atlantic water. The exact species to which a stranded sunfish belonged is still under investigation.

Marine mammals are very popular: some temporary or permanent exhibitions were opened in 2019, and the skeleton of a sperm whale that was washed ashore in 1989 was excavated with the aim of preparing and exhibiting it. Finally, the report also contains editorials on underwater noise and porpoises, the international dimension of marine mammal research, some well-known seals in Nieuwpoort, and extreme fluctuations in the weight of seals.

Report of 2018

As every year, RBINS has collected data on marine mammals in Belgium. For 2018, this happened with the cooperation of SEALIFE Blankenberge, the University of Liège and Natuurpunt. In 2018, 134 marine mammals washed ashore dead or dying in Belgium, concerning 89 harbour porpoises, 1 white-beaked dolphin, 1 fin whale, 18 grey seals, 11 harbour seals and 14 seals that were not identified to species. In addition, SEALIFE Blankenberge took 30 seals into care: 17 grey and 13 harbour seals (the highest number of grey seals ever, and for the first time more grey than common seals).

Ten percent of the harbour porpoises for which the cause of death could be established had died from drowning in fishing nets, and 30% from predation by grey seals. The fin whale, an 18-metre-long male found dead at sea, presumably died from a natural cause. The number of stranded dead and dying seals (43) was the highest number ever. Six of the grey and one of the harbour seals were believed to have died from incidental capture. One grey seal died entangled in a piece of nylon rope, and another choked on a flatfish.

The most striking sightings in 2018 concerned very high numbers of harbour porpoises in April (estimated at almost 20,000 in the Belgian waters, based on aerial counts) and the relatively frequent occurrence of bottlenose dolphins.

The annual report also contains editorials about the sense and nonsense of taking seals into care, the impact of waste on marine mammals and the use of the port of Nieuwpoort as a resting place for seals.

Report of 2017

The newest marine mammal report presents an overview of marine mammals and remarkable fish in Belgium in 2017. It also focusses on the causes of death of beached animals and the revalidation of animals that were taken into care, and contains opinion pieces about Arctic climate refugees and the grey seal in our coastal waters.

In 2017, the number of stranded harbour porpoises more or less equalled the average of the past 10 years. Nearly 60% of the 93 harbour porpoises that stranded along the Belgian coast in 2017, died due to predation by the grey seal or incidental catch.

Two observations of white-beaked dolphins were documented in 2017, while bottle-nosed dolphins were reported more regularly. Also one deceased individual of both these species washed ashore. A dead minke whale floated through Belgian waters, and eventually washed ashore in the Netherlands.

With 10 common seals, 8 grey seals and 19 non-identified seals, the number of dead or dying seals exhibits a rising trend. Additionally, 22 common and 6 grey seals were taken into temporary care at SEALIFE Blankenberge. A remarkably high number of seals that had been injured by fishing hooks was observed in the port of Nieuwpoort.

The bowhead whale that stayed off the coastal towns of Ostend and Middelkerke on 31 March and 1 April was the first ever to be reported for the entire North Sea. Barely a year after the stranding of a narwhal, the sighting of this animal, of a species that inhabits very northerly waters, instigates a lot of speculation about the effects of climate change on marine life in the Arctic, and perhaps at a global scale.

Report of 2016

The newest marine mammal report presents an overview of marine mammals and remarkable fish washed ashore in Belgium in 2016. It also focuses on the causes of death, revalidation and release of animals that were taken into care, and briefly introduces the research on the influence of offshore windmill parks on the harbour porpoise.

The most remarkable stranding of 2016 undoubtedly concerned a narwhal, an Arctic animal that was last observed in the North Sea almost 70 years ago. Also two humpback whales were seen, and a basking shark and two ocean sunfishes washed ashore.

With 137 animals, the number of harbour porpoises that washed ashore was again very high. The major causes of death were incidental catch in fishing gear and predation by grey seals. Harbour porpoises were shown to avoid an area up to a distance of 20 km during the construction of offshore wind turbines.

White-beaked dolphins were reported on one day only, in contrast to bottlenose dolphins that were regular and prominent guests again. In April a severely decomposed male bottlenose dolphin washed ashore, followed by a heavily decomposed dolphin along the Scheldt a few days later. The species could not be determined anymore.

The number of strandings of dead and dying seals remained similar to previous years: six harbour seals, 11 grey and 12 unidentified seals. SEA LIFE Blankenberge took care of record high numbers: 15 grey and 24 common seals, including an albino animal. No less than 12 grey and 20 common seals could be returned to the wild after revalidation.