Innvandring fra Storbritannia til Norge av havert (Halichoerus grypus)

The present article on the migration of grey seals from British waters to the Norwegian coast is mainly intended to arouse the interest of the coastal population of Norway for the British marking experiments. The first part of the article gives a review of the Farne Island grey seal population and the scientific work carried out since 1951 by the Natura! History Society of Northumberland. Durham and Newcastle upon Tyne. Likewise the tagging work on the Orkneys, Hebrides and North Rona by the Nature Conservancy, Edinburgh is shortly reviewed. At the end of January 1962 altogether 25 marked grey seals have been recaptured in Norway. These grey seals are coming partly from the Farne Islands and partly from the Orkneys. A more detailed list is given of the recaptures and a map showing the localities. Almost all animals recaptured in Norway have been found drowned in gill nets. One animal were taken alive and transferred to the Bergen Aquarium where it died after a few days. The migration routes to Norway seem to have a certain pattern. The Farne Islands grey seals are mostly recaptured in the Stavanger area, while the Orkney grey seals mostly are found in the BergenStad area. As shown in the map there are, however, a few exceptions to this general pattern. The direction of migration both from Farne Islands and from the Orkneys is towards northeast, and it is suggested that possibly the frequent southwesterly gales in November-December are one of the factors influencing the swimming direction of the very young grey seals leaving their home waters. A review is given of the occurrence of grey seals on the Norwegian coast where they have been very scarce since the beginning of this century. Specially mentioned is the Halten colony which in the 1870-ies numbered 5-600 animals. In 1954 this colony was strong1y reduced and counted less than 50 animals. The grey seals in the whole Halten district was finally protected by law in April 1953. There is no information on the present size of this colony, but it is still considered to be very small. In conclusion is mentioned the possiblity of grey seals from the British coast becoming established in Norway or augmenting the existing small Halten colony. However, the answer to this problem lies in future recoveries of mature animals bearing a British tag.