Grey seals versus men

Over the past weeks, horrendous messages appeared in the press about grey seals that ‘shall’ attack swimmers along our coastline. Some nuancing is required.

Grey seal, 23 January 2007 (copyright KBIN)

Those that followed the media over the last two weeks must have noticed it : newspapers, websites and news programs on TV and radio warned for grey seals, which were portrayed as murderous creatures that make our beaches and coastal waters unsafe and will soon start violating tourists.

It all started with an article in La Dernière Heure (DH) « Il va y avoir des attaques de phoques en Belgique » (« There will be attacks of grey seals in Belgium »; Wednesday 9 August), based on an interview with our science communicator Kelle Moreau. Also the front page of the paper unequivocally and alarmistically advertised: « Alerte aux phoques tueurs à la côte belge » (« Warning for killing seals along the Belgian coast »). Het Laatste Nieuws (HLN) copied the message (« Seals will attack swimmers at the coast »), be it in a drastically reduced form in which particularly the sensation remained. Subsequently, the unfortunate message was spread widely, both by the French and the Dutch-speaking press.

Grey seal and a dog that is allowed too close, 14 March 2017 (copyright Roland François).

We want to nuance a number of things :

The intention of the article in La Dernière Heure was to inform about the strandings of marine mammals and rare fishes on the Flemish beaches in 2016. Predation by grey seals was mentioned as one of the causes of death of stranded harbour porpoises, in the context of which the journalist asked whether it can be excluded that a grey seal would ever attack a human being. Our science communicator responded that such an event cannot be excluded, but that such cases would rather qualify as accidents rather than manifestations of aggression or attempted predation. Grey seals are big and strong animals, with substantial teeth and claws, that could easily wound a human being as a consequence of « disturbance » (of a resting animal on a beach, a mother with cub, …), « confusion » (a foraging animal in turbid water may mistake a human being for something else?) or even of playful behaviour. However, our biologists believe that the chance of such an interaction with a grey seal in our waters remains very small (but exists), and that panic is unnecessary. We must definitely not avoid our coastal waters and beaches, and the grey seal is absolutely not an unwanted guest on our coast. The only message is that we should realise that grey seals are predators, that we should have a healthy respect for these animals, and best leave them alone.

Grey seal and swimmer (copyright Diederik D’Hert)

The fact that grey seals have harbour porpoises on their menu was also shown for the first time by researchers of our institute, after a few porpoises washed ashore in 2011 with wounds that – after analysis – appeared to have been inflicted by grey seals. Initially, this news caused great disbelief. Only after confirmation by analyses of foreign scientists, this new phenomenon was widely accepted.

Annual report strandings 2016

As part of the implementation of the Royal Decree on marine species protection in the Belgian national waters, annual reports on observations and strandings of marine mammals in Belgium are compiled.

The new marine mammal report (download on http://www.marinemammals.be/reports) presents an overview of marine mammals and remarkable fish washed ashore in Belgium in 2016. It also focusses 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.