Hooded seals (Cystophora cristata) are primarily found in the Arctic and northern Atlantic Oceans, near Jan Meyen Island, off Newfoundland, Labrador and Davis Strait.1,2 They like drifting pack ice and deep Arctic waters. Hooded seals are known to be a very migratory species and have been seen as far south as the Canary Islands and Guadaloupe.2 One of the main pupping and breeding grounds is near Jan Meyen Island.3 Pupping season is, throughout all areas, in late March and early April. The animals molt from June to August.4 Hooded seals hold the record of the shortest lactation period of all mammals. The average nursing time is only 4 days in which the pups double their weight. After those few days, the dams leave their offspring.5
Within a period of several months in 2010/2011, three young female animals got into the North Sea and further to the German Wadden Sea. One animal died on the transfer to the Seal Center Friedrichskoog. The other two were nursed and raised in the center for several months before they were released back into the North Sea. "Wicki" was found with a weight of 44.5 kg on the island Föhr on November 11, 2010, and was released on April 13, 2011 (79.6 kg). "Eve" was found with a weight of 35 kg right near the rehabilitation center in Friedrichskoog on August 24, 2011, and was released on October 13, 2011 (51 kg). Before their release, data loggers (Wildlife Computers, Inc.,Redmond, WA 98052, USA) were attached to their heads to track their route. Wicki's tag reported for only about one month. She swam straight west to the east coast of England, then up north keeping nearshore to Northumberland before heading east again. The logger stopped transmitting in the middle of the North Sea, probably due to molt. Eve also swam to England but hit the coast between Dundee and Aberdeen for the first time. Unlike Wicki, Eve stayed in Scotland and later England. She swam up and down the coast, before she was found on a beach near Skegness and taken to the Seal Sanctuary Natureland in Skegness. When found she only weighed 30 kg. As neither the Norwegian nor the Icelandic or other government wanted the hooded seal back in their waters, due to possible diseases caught in the North Sea, Eve had to be kept at the sanctuary.
The authors wish to thank the staff of both seal centers Friedrichskoog and Skegness, Prof. Dr. Siebert of the Institute for Terrestrial and Aquatic Wildlife Research. The authors thank Jonas Teilmann for the help with the ARGOS data.
* Presenting author
1. Hooded Seal (Cystophora cristata). National Marine Fisheries Service; 1987.
2. Hooded Seals (Cystophora cristata). http://marinebio.org/species.asp?id=304.
3. Harris DE, Lelli B, Jakush G, Early G. Hooded seal (Cystophora cristata) records from the southern Gulf of Maine. Northeastern Naturalist. 2001;8(4):427.
4. Kovacs KM. Mating strategies in male hooded seals (Cystophora cristata)? Canadian Journal of Zoology. 1990;68(12):2499.
5. Iverson SJ, Oftedal OT, Bowen WD, Boness DJ, Sampugna J. Prenatal and postnatal transfer of fatty acids from mother to pup in the hooded seal. Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology. 1995;165(1):1–12.