Northern Gannets are passage migrants in Dutch coastal waters. Ship-based seabird surveys revealed that Northern Gannets occur year-round in the Southern North Sea, a finding that has been supported by beached bird surveys. Most of the beached Northern Gannets in The Netherlands were either oiled, or entangled in fishing gear. Typical patterns of oiling (birds seem to hit the oil mainly during take-off) and types of ropes and fishing gear responsible for most Northern Gannet deaths are described. Oil rates in beached Northern Gannets declined significantly over time, but are still very high (79% in adults and immatures, 47% in juveniles). On the contrary, the frequency of entangled Northern Gannets increased significantly recent years (1977-89 5%, 1990s 7.5%). In the 1980s, most were entangled in fishnets or in various types of ropes and nylon fibres from trawlers. In the 1990s most entangled Northern Gannets were killed in nylon fish line, normally used by sports anglers. Approximately 450 Northern Gannets are estimated to wash ashore annually. Relatively few juvenile Northern Gannets have been found and the shift in age distribution through the year reflects the age composition of Northern Gannets in the Southern Bight. The Atlantic breeding population has increased during most of the 20th century and in accordance with that, numbers of Northern Gannets recorded during seawatching have increased over the past 30 years. These trends are not reflected in Northern Gannet strandings, the frequency of which seems to have declined markedly after the late 1940s and have been stable over the last 30 years.
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