Marine Mammals

Marine mammals regarded as indigenous species in the Wadden Sea are the harbour (or common) seal Phoca vitulina, grey seal Halichoerus grypus, and harbour porpoise Phocoena phocoena. Several other marine mammal species, both pinnipeds and cetaceans, occur in the Wadden Sea and adjacent North Sea, either as stragglers or regular visitors. Stranding records since the 1999 Quality Status Report, show that occasionally five other species of seals are encountered in the Wadden Sea area and adjacent North Sea. These are: the harp seal Phoca groenlandica, hooded seal Cystophora cristata, ringed seal Phoca hispida, bearded seal Erignathus barbatus and walrus Odobenus rosmarus, all of which have a more northerly distribution. Cetaceans documented on the Wadden Sea coast are the white-beaked dolphin Lagenorhynchus albirostris, white-sided dolphin Lagenorhynchus acutus. Remarkable are the occurrence (live and dead) of large cetaceans in the Wadden Sea region since the 1999 QSR, notable six minke whales Balaenoptera acutorostrata, one humpback whale Megaptera novaeangliae, two fin whales Balaenoptera physalus and thirteen sperm whales Physeter macrocephalus.

Link to Seal Management (CMS-Seal Agreement, Trilateral Seal Management Plan)

1. Harbour Seals

Result of the aerial survey in 2011

The harbour seal Phoca vitulina  is the animal most commonly associated with the Wadden Sea. They haul-out on sand banks and catch fish in the tidal channels and the open sea. The population has recovered well from the last distemper epizootic in 2002. Recent investigation have revealed that harbour seals are using the Wadden Sea but also the neighboring North Sea to a much greater degree than was previously known.

 

2. Grey Seals

Result of the aerial survey in 2010-2011

The grey seal Halichoerus grypus was a common species along mainland Europe during the Neolithic and early Bronze Age (4000 - 1200 BC). Most of the sub-fossil seals remain found in Dutch deposits dated between 2000 BC and 1000 AD, which is comparable to finds in other parts of the Wadden Sea. By the end of the Middle Ages (1400-1500 AD), grey seals virtually disappeared from the Wadden Sea area. Up until the mid-20th century, only straggling animals were reported on the Dutch, German and Danish North Sea coasts.
In recent times, about three decades ago, grey seals started to re-establish themselves in the Wadden Sea, first a haulout rookery off the German Island of Amrum, followed later by a few
rookeries in the western part of the Dutch Wadden Sea. More regular surveys from boats have been carried out in the Netherlands since 1980 and from 1988 onwards off Amrum. Maybe the re-colonisation has started sometime earlier, but grey seals present were just taken as harbour seals.

Present occurrence
The grey seal rookeries in the Netherlands are mainly found in the western part of the Wadden Sea, although gradually more single animals and small haul-out groups are observed in the middle and eastern part. Numbers at the main haul/outs have increased exponentially since 1980, on aver age by 20% annually.
In the westernmost part of the German Wadden Sea (Lower Saxony), small groups have recently been observed near the islands of Borkum, Norderney and Juist, and single ones in the Weser-Elbe estuary.
The haulout rookery off Amrum (Schleswig-Holstein) is growing and moult counts (carried out from boats) indicate an annual increase of about 4-5%.
Another stronghold of grey seals in the German Bight is located on the island of Helgoland. Regular occurrence has been known there since 1989. Only straggling seals are found in the Danish Wadden Sea.

Trilateral Seal Expert Group (TSEG)
Sophie Brasseur and Peter Reijnders, IMARES, Texel, The Netherlands
Thomas Borchardt, LKN Schleswig-Holstein, Nationalparkverwaltung, Germany
Ursula Siebert, FTZ-Büsum der Universität Kiel, Schleswig-Holstein, Germany
Sven Ramdohr, LAVES Cuxhaven, Niedersachsen, Germany
Richard Czeck, Nationalparkverwaltung Niedersächsisches Wattenmeer, Niedersachsen, Germany

Peter Körber, BSU, Nationalpark Hamburgisches Wattenmeer, Hamburg, Germany
Lasse Fast Jensen, Fiskeri- og Søfartmuseet, Esbjerg, Denmark
Jonas Teilmann, National Environmental Research Institute, Aarhus University, Denmark
 

 

Download

QSR 2009: Thematic Report 20: Marine Mammals (Reijnders et al.)

QSR 2004: Chapter 13: Marine Mammals