Seabird Group Seabird Group

Mission accomplished: chronic North Sea oil pollution now at acceptable levels, with Common Guillemots Uria aalge as sentinels

In memory of Peter Hope Jones
Kees (C. J.) Camphuysen1* ORCID logo

1 Royal Netherlands Institute for Sea Research (NIOZ), P.O. Box 59, 1790 AB Den Burg, Texel; Nederlandse Zeevogelgroep (NZG), Den Helder, The Netherlands.

Full paper


Marine oil pollution has been an issue of concern for at least a century. The earliest reports contained outrage over oil-contaminated dead seabirds found ashore. This paper reports on observed trends in strandings and oil rates of Common Guillemots Uria aalge to illustrate the history of oil pollution and its effects in the North Sea. This paper is also a tribute to Peter Hope Jones, who brought systematic beached bird surveys and oil-spill impact assessments to a higher level, by implementing detailed research on affected wildlife. In recent decades, unexpectedly, the oil problem has disappeared almost completely from the North Sea. Given the global nature of current environmental issues, including the climate and biodiversity crises, it may be instructive to examine the background to this stunning success. A short history of major oil events is presented, including the measures taken to reduce the oil problem. It required a succession of major oil incidents to push the community into action. The process of international conventions was notoriously slow, and the implementation of concrete measures even slower, as economic arguments prevailed to prevent or delay immediate action.


Marine oil pollution has been an issue of concern for at least a century. One of the most dramatic and visible effects of oil pollution is the contamination and associated mass mortality of seabirds at sea (Bourne 1976; Croxall 1977; Reineking & Vauk 1982; Clark 1984; Dunnet 1987; Camphuysen 1989a; Danielsen et al. 1990). For decades, it seemed a tough nut to crack. Yet, miraculously, and in the course of only a decade or two, the problem has now disappeared almost completely from the North Sea, and in fact from most other areas worldwide. Give or take a few oil incidents, chronic oil pollution is now, quite suddenly, something from the (recent) past. Now that many people get depressed and feel frustrated by the global nature of current environmental issues, such as the climate and biodiversity crises, the effects of agriculture or fisheries, plastic pollution, or ‘just’ the human population increase, it may be worthwhile to document this stunning success. How did it come about, how did it develop and escalate, and, most of all, how could it end?

Oil pollution (petroleum hydrocarbons, PHCs) enters the marine environment from a variety of sources, including transport (e.g. deliberate discharges or accidental leakages of bilge and fuel oil), tanker operations or shipping accidents, atmospheric emissions, releases or leakages from coastal refineries, offshore production instal- lations or marine terminals, from urban or river run-off (e.g. municipal or industrial waste), together with natural inputs (Wardley-Smith 1976; NRC 1985; Wolfe 1985; Clark 2001). Here I will focus on the situation in the North Sea, where the prime sources for most of the easily visible chronic marine oil pollution were (and in a way still are) transport, releases or leakages from offshore installations, and shipping incidents (e.g. Dunnet 1987; Dahlmann et al. 1994; Camphuysen 2007a).

The first written reports of marine oil pollution expressed outrage over oil- contaminated dead seabirds found on beaches (Anon. 1910; Dawson 1911; Verwey 1915). Even then it was clear that divers (loons), grebes, sea ducks and auks were the groups most severely affected by oil. This northern-hemisphere perspective was subsequently extended to include penguins and cormorants, and it was confirmed that species that spent the majority of their time swimming had a higher sensitivity to oil pollution than more aerial groups such as tubenoses, skuas, gulls and terns (King & Sanger 1979; Gandini et al. 1994; Camphuysen 2007a). Since the earliest accounts, the publication record on oil-related seabird mortality and oil incidents is massive.

Common Guillemots Uria aalge (hereafter ‘Guillemots’) have been over- represented in published reports of oiled birds in the North Sea. Abundant and highly vulnerable seabirds as they are, they commonly washed ashore and are still often found on beaches today. It was not until the early twenty-first century that the EU Marine Strategy Framework Directive insisted on the implementation of an independent indicator to evaluate the effectiveness of measures to reduce chronic oil pollution (OSPAR 2010). The so-called ‘oiled-Guillemot-EcoQO’ was adopted, an Ecological Quality Objective (EcoQO) to assess fluctuations, patterns and trends in chronic marine oil pollution, and beached bird surveys officially became that independent monitoring instrument. The oil rate in Guillemots was selected because the species was abundant enough to be useful as a ‘Canary in the coalmine’ in all North Sea countries (OSPAR Commission 2009).

The oiled-Guillemot-EcoQO came late, and was just a measuring instrument. At least 100 years had already been spent on attempts to reduce the oil problem, but initially with little effect. To refresh our collective memory, it seems timely to present a short history and a timeline of both the worrying signals, as published since the early twentieth century, and the measures taken to reduce the oil problem.

This paper reports on observed trends in strandings and oil rates (% oiled) of Guillemots to document the history of oil pollution and its effects in the North Sea. It uses data collected from birds that washed ashore along the Dutch coast over the past 120 years (1900–2020), or throughout the entire twentieth and early twenty-first centuries. But not only that. It was the late Peter Hope Jones who, in the late 1970s, brought both systematic beached bird surveys and incidental oil- spill impact assessments to a higher level, by implementing more detailed research on affected wildlife. He saw the ecological importance as well as the relevance for seabird conservation of collecting as much information as possible from animals that were otherwise largely out of reach, far out at sea. An important step was to collect and study carcasses such that, for example, age composition and the (likely) colonies of origin could be assessed. As a tribute to his legacy, I will therefore present and discuss results obtained by using his initial protocols (Hope Jones et al. 1978, 1982, 1984, 1985, 1988; Hope Jones & Morgan 1979), partly updated in later years (Kuschert et al. 1981; Camphuysen 1983, 1995a, 2007b; Maas 1983; Sandee 1983; Franeker 1983; Harris 2014). As a result of these ‘extra’ observations, regular beached bird surveys became more than just a demonstration of an existing environmental problem. We were able to learn things from birds that were otherwise notoriously hard to study. The results are valuable pieces of the jigsaw puzzle, especially when combined with results from studies on breeding grounds, at-sea surveys, seawatching, ringing studies, dietary studies using proxies such as eDNA, stable isotopes or fatty acids, and novel tracking studies.


Anon. 1910. Eisentenhavarie bei Dago. Neue Baltische Waidmannsblätter 6: 489.

Anon. 1923. Duitschland - Tegen olievervuiling. Gooi en Eemlander 23 juni 1923.

Anon. 1934. Stookolie. Amoeba 13: 79. [Crossref]

Anon. 1955. Handleiding ter voorkoming van de verontreiniging van de zee door olie. Koninklijke Nederlandsche Reedersvereeniging, ‘s-Gravenhage.

Anon. 1967. The ‘Torrey Canyon’. Presented to Parliament by the Secretary of State for the Home Department, April 1967. HMSO, London.

Anon. 1995. JAMP Guidelines on standard methodology for the use of oiled beached birds as indicators of marine oil pollution. Monitoring guidelines, OSPAR Convention for the Protection of the Marine Environment of the North-East Atlantic, Ref. No. 95–06e.

Anon. 2002. Bergen Declaration. Ministerial declaration Fifth International Conference on the Protection of the North Sea, 20–21 March 2002, Bergen, Norway.

Anon. 2012. Mariene Strategie voor het Nederlandse deel van de Noordzee 2012–2020, Deel 1. Rapport, Ministeries I&M en ELI, ‘s-Gravenhage.

Anon. 2021. January 1862: Elisabeth Watts exports first Pennsylvania oil to London.

Barclay-Smith, P. 1930. Progress made in combatting oil discharges at sea. Bird Lore 32: 397–400.

Barrett, R. T. 1979. Small oil spill kills 10–20,000 seabirds in North Norway. Marine Pollution Bulletin 10: 253–255. [Crossref]

Barrett, R. T., Anker-Nilssen, T., Bakken, V., Strøm, H. Krasnov, Y. & Aarvak, T. 2008. Biometrics as a determinant of the origins of seabirds killed in oil spills and other incidents. Bird Conservation International 18: 229–241. [Crossref]

Begg, G. S., Reid, J. B., Tasker, M. L. & Webb, A. 1997. Assessing the vulnerability of seabirds to oil pollution: sensitivity to spatial scale. Colonial Waterbirds 20: 339–352. [Crossref]

van den Berg, A. B. & Bosman, C. A. W. 2001. Zeldzame vogels van Nederland. Tweede druk; Avifauna van Nederland, 1. KNNV Uitgeverij Utrecht en GMB Uitgeverij, Haarlem.

Bibby, C. J. 1981. An experiment on the recovery of dead birds from the North Sea. Ornis Scandinavica 12: 261–265. [Crossref]

Bibby, C. J. & Lloyd, C. S. 1977. Experiments to determine the fate of dead birds at sea. Biological Conservation 12: 295–309. [Crossref]

Blake, B. F. 1984. Diet and fish stock availability as possible factors in the mass death of auks in the North Sea. Journal of Experimental Marine Biology and Ecology 76: 89–103. [Crossref]

Blake, B. F., Tasker, M. L., Jones, P. H., Dixon, T. J., Mitchell, R. & Langslow, D. R. 1984. Seabird Distribution in the North Sea. Nature Conservancy Council, Huntingdon.

Bootsgezel, J. J. 1933. Stookolie. De Levende Natuur 38: 285–287.

Bourne, W. R. P. 1967. The Torrey Canyon disaster. Seabird Bulletin 3: 4–11.

Bourne, W. R. P. 1970. Special review: after the ‘Torrey Canyon’ Disaster. Ibis 112: 120–125.

Bourne, W. R. P. 1976. Seabirds and pollution. In: Johnston R. (ed.), Marine Pollution: 403–502. Academic Press, London.

Bourne, W. R. P. & Devlin, T. R. E. 1970. International Beached Bird Survey 1969. Birds 3: 12–13.

Bourne, W. R. P., Parrack, J. D. & Potts, G. R. 1967. Birds killed in the Torrey Canyon Disaster. Nature 215: 1123–1125. [Crossref]

Brada, J. D. 1950. Olieslachtoffers. Vanellus 3: 2–4.

Camphuysen, C. J. 1983. Leeftijdsbepaling en ondersoorten bij de Papegaaiduiker Fratercula arctica. Nieuwsbrief NSO 4: 28–32.

Camphuysen, C. J. 1989a. Beached Bird Surveys in The Netherlands 1915–1988: seabird mortality in the southern North Sea since the early days of oil pollution. Techn. Rapport Vogelbescherming 1, Werkgroep Noordzee, Amsterdam.

Camphuysen, C. J. 1989b. Vondst van een noordelijke Zeekoet Uria aalge hyperborea in Nederland. Limosa 62: 47–48.

Camphuysen, C. J. 1990. Biometrics of auks at Jan Mayen. Seabird 12: 7–10.

Camphuysen, C. J. 1992. Auk wrecks in the southern North Sea, 1981–1991: oil pollution or food shortage? In: Tasker, M. L. (ed.), Proceedings of the Seabird Group Conference, ‘European Seabirds’, Glasgow, 27–29 March 1992: 23.

Camphuysen, C. J. 1995a. Leeftijdsbepaling van Zeekoet Uria aalge en Alk Alca torda in de hand. Sula 9: 1–22.

Camphuysen, C. J. 1995b. Olieslachtoffers langs de Nederlandse kust als indicatoren van de vervuiling van de zee met olie. Sula 9 (special issue): 1–90, I–XX.

Camphuysen, C. J. 1998. Beached bird surveys indicate decline in chronic oil pollution in the North Sea. Marine Pollution Bulletin 36: 519–526. [Crossref]

Camphuysen, C. J. 2002. Post-fledging dispersal of Common Guillemots Uria aalge guarding chicks in the North Sea: the effect of predator presence and prey availability at sea. Ardea 90: 103–119.

Camphuysen, C. J. 2007a. Chronic oil pollution in Europe, a status report. Report Royal Netherlands Institute for Sea Research, commissioned by International Fund for Animal Welfare (IFAW), Brussels.

Camphuysen, C. J. 2007b. Alcidae Auks. In: Camphuysen, C. J., Bao, R., Nijkamp, H. & Heubeck, M. (eds.), Handbook on Oil Impact Assessment. Technical document 4.1, Assessing the damage. Report to DG Environment, European Commission, Grant Agreement 07.030900/2005/42907/ SUB/A5, Version 1.0, Royal Netherlands Institute for Sea Research, Texel. Available at

Camphuysen, C. J. 2009. Het gebruik van zeetrektellingen bij de analyse van populati- eschommelingen van duikers Gaviidae langs de kust. Sula 22: 1–24.

Camphuysen, C. J. 2010. Declines in oil-rates of stranded birds in the North Sea highlight spatial patterns in reductions of chronic oil pollution. Marine Pollution Bulletin 60: 1299–1306. [Crossref]

Camphuysen, C. J. 2020. Beached bird surveys in The Netherlands, winter 2019/20. NIOZ Report, RWS Centrale Informatievoorziening BM 20.24, Royal Netherlands Institute for Sea Research, Texel.

Camphuysen, C. J. 2021. Beached bird surveys in The Netherlands, winter 2020/21. NIOZ Report, RWS Centrale Informatievoorziening BM 21.16, September 2021. Royal Netherlands Institute for Sea Research, Texel.

Camphuysen, C. J. & Dahlmann, G. 1995. Guidelines on standard methodology for the use of (oiled) beached birds as indicators of marine pollution. Ad Hoc working group on Monitoring, Oslo and Paris Convention for the Prevention of Marine Pollution. MON 95/7, Agenda item 7, 13–17 November 1995, Copenhagen.

Camphuysen, C. J. & Heubeck M. 2001. Marine oil pollution and beached bird surveys: the development of a sensitive monitoring instrument. Environmental Pollution 112: 443–461. [Crossref]

Camphuysen, C. J. & Leopold, M.F. 2005. The Tricolor oil spill: characteristics of seabirds found oiled in The Netherlands. Atlantic Seabirds 6: 109–128.

Camphuysen, C. J. & van der Meer J. 1996. Recent trends in oiled seabirds. Ad Hoc working group on Monitoring, Oslo and Paris Convention for the Prevention of Marine Pollution, Environmental Assessment and Monitoring Committee (ASMO). MON 1995 summary record: 20–48, Copenhagen.

Camphuysen, C. J. & Vollaard, B. 2015. Oil pollution in the Dutch sector of the North Sea. In: Carpenter, A. (ed.), Oil Pollution in the North Sea: 117–140. Springer-Verlag, Berlin. [Crossref]

Camphuysen C. J., Chardine, J., Frederiksen, M. & Nunes, M. 2005. Review of the impacts of recent major oil spills on seabirds. In: Anon. (ed.) Report of the Working Group on Seabird Ecology, Texel, 29 March–1 April 2005. Oceanography Committee, ICES CM 2005/C:05, Ref. ACME+E, International Council for the Exploration of the Sea, Copenhagen, Denmark.

Carpenter, A. (ed.) 2015. Oil Pollution in the North Sea. Handbook of Environmental Chemistry. Springer-Verlag, Berlin, Heidelberg, New York.

Carpenter, A. 2019. Oil pollution in the North Sea: the impact of governance measures on oil pollution over several decades. Hydrobiologia 845: 109–127. [Crossref]

Carter, I. C., Williams, J. M., Webb, A. & Tasker, M. L. 1993. Seabird concentrations in the North Sea: an atlas of vulnerability to surface pollutants. Joint Nature Conservation Committee, Aberdeen.

Clark, R. B. 1984. Impact of oil pollution on seabirds. Environmental Pollution Series A 33: 1–22. [Crossref]

Clark, R. B. 2001. Marine Pollution, 5th edition, Oxford University Press, Oxford.

Croxall, J. P. 1977. The effect of oil on seabirds. apports et Procès-Verbaux des Réunions du Conseil Permanent International pour l’Exploration de la Mer 171: 191–195.

Dahlmann, G., Timm, D., Averbeck, C., Camphuysen, C. J. & Skov, H. 1994. Oiled seabirds: comparative investigations on oiled seabirds and oiled beaches in The Netherlands, Denmark and Germany (1990–1993). Marine Pollution Bulletin 28: 305–310. [Crossref]

Danielsen, F., Skov, H., Durinck, J. & Christensen, K. D. 1990. Seabirds and oil pollution in Danish waters 1984–89. Dansk Ornitologisk Forenings Tidsskrift 84: 8–9.

Dawson, W. L. 1911. Another fortnight on the Farallones. Condor 13: 171–183. [Crossref]

Drost, R. 1959. Oil pollution on the coast of the German Federal Republic. Proceedings of the International Conference on Oil Pollution of the Sea, Copenhagen, 3–4 July 1959: 73–75.

Dunnet, G. M. 1982. Oil pollution and seabird populations. Philosophical Transactions of the Royal Society of London B 297: 413–427. [Crossref]

Dunnet, G. M. 1987. Seabirds and North Sea oil. Philosophical Transactions of the Royal Society of London B 316: 513–524. [Crossref]

Ebbesmeyer, C. C. 2004. Where the toys are. Beachcombers’ Alert! 8: 1–8.

European Commission 2010. Issue 4 (Seabirds), EcoQO element (f), Commission Decision of 2010, Chapter 8.2, Effects of contaminants; EU 2010.

Fernández Boán M., García, L., Ramos, A., Dopico, M., Bigas, D., Castelló, J., Bao, R. & Camphuysen, C. J. 2005. Características generales de la población de Arao Común (Uria aalge) afectada por el accidente del petrolero Prestige en la costa de A Coruña. Oral presentation VI Congreso Galego de Ornitoloxía e V Jornadas Ornitológicas Cantábricas, in Viveiro, Lugo (Spain), 29–31 October, 2005.

van Franeker, J. A. 1983. Inwendig onderzoek aan zeevogels. Nieuwsbrief NSO 4: 144–167.

Furness, R. W. & Camphuysen, C. J. 1997. Seabirds as monitors of the marine environment. ICES Journal of Marine Science 54: 726–737. [Crossref]

Gandini, P., Boersma, P. D., Frere, E., Gandini, M., Holik, T. & Lichtstein, V. 1994. Magellanic Penguins (Spheniscus magellanicus) affected by chronic petroleum pollution along the coast of Chubut, Argentina. Auk 111: 20–27. [Crossref]

Grol, C. 2021. Oliebedrijven gaan samen opruimen in de Noordzee. Financieel Dagblad 5 February 2021.

Harris, M. P. 2014. Aging Atlantic Puffins Fratercula arctica in summer and winter. Seabird 27: 22–40. [Crossref]

Harris, M. P. & Swann, B. 2002. Common Guillemot Uria aalge. In: Wernham, C. et al. (eds.), The Migration Atlas: Movements of the Birds of Britain and Ireland: 397–400. Poyser, London.

Harris, M. P. & Wanless, S. 1990. Moult and autumn colony attendance of auks. British Birds 83: 55–66.

Harris, M. P., Wanless, S., Ballesteros, M., Moe, B., Daunt, F. & Erikstad, K. E. 2015. Geolocators reveal an unsuspected moulting area for Isle of May Common Guillemots Uria aalge. Bird Study 62: 267–270. [Crossref]

Hautekiet, M. R. 1955. Vijf jaar stookolieslachtoffers. Wielewaal 11: 289–294.

Heubeck, M. 1992. The occurrence of dead auks on Shetland beaches, March 1979 to February 1992. In: Osborn, K. (ed.), Shetland Bird Report 1991: 94–103. Shetland Bird Club, Lerwick.

Heubeck, M. 1995. Shetland beached bird surveys: national and European context. Proceedings of the Royal Society of Edinburgh 103: 165–179. [Crossref]

Heubeck, M., Meek, E. & Suddaby, D. 1992. The occurrence of dead auks (Alcidae) on beaches in Orkney and Shetland, 1976–91. Sula 6: 1–18.

Heubeck, M. & Mellor, M. 2016. SOTEAG Ornithological Monitoring Programme, 2016 report. The Shetland Oil Terminal Environmental Advisory Group 2016, Univ. of Aberdeen.

Hlady, D. A. & Burger, A. E. 1993. Drift-block experiments to analyse the mortality of oiled seabirds off Vancouver Island, British Columbia. Marine Pollution Bulletin 26: 495–501. [Crossref]

Hope Jones, P. 1984. Skins of Guillemots Uria aalge and Razorbills Alca torda examined at Cascais, Portugal, in May 1982. Memorias do Museo do Mar, Serie Zoologica 3: 1–10.

Hope Jones, P. 1985. Determination of age, sex and origin of guillemots and razorbills killed in oilspills and other incidents. MSc thesis, Open University.

Hope Jones, P. 1988. The European cline in wing length of Guillemots Uria aalge. Seabird 11: 19–21.

Hope Jones, P. & Morgan, P. J. 1979. Collection and use of oiled seabirds in Wales. BTO News 99: 4.

Hope Jones, P., Monnat, J. Y., Cadbury, C. J. & Stowe, T. J. 1978. Birds oiled during the Amoco Cadiz incident: an interim report. Marine Pollution Bulletin 9: 307–310. [Crossref]

Hope Jones, P., Monnat, J. Y. & Harris, M. P. 1982. Origins age and sex of auks (Alcidae) killed in the ‘Amoco Cadiz’ oiling incident in Brittany, March 1978. Seabird Report 6: 122–130.

Hudson, R. 1969. Beached birds survey. British Birds 62: 45–46.

Huijer, K. 2005. Trends in oil spills from tanker ships 1995–2004. International Tanker Owners Pollution Federation (ITOPF), London.

ITOPF 2008. Tanker spills: the last 40 years. Ocean Orbit: the Newsletter of the International Tanker Owners Pollution Federation Limited September 2008: 5.

Joensen, A. H. 1972. Studies on oil pollution and seabirds in Denmark 1968–1971. Danish Review of Game Biology 6: 1–24.

Jongens, G. W. 1937. Olieslachtoffers. De Levende Natuur 41: 382.

Keijl, G. O. & Camphuysen, C. J. 1992. Resultaten van een verdriftingsexperiment voor de Nederlandse kust, februari 1991. Sula 6: 41–49.

King, J. G. & Sanger, G. A. 1979. Oil vulnerability index for marine oriented birds. In: Bartonek, J. C. & Nettleship, D. N. (eds.), Conservation of Marine Birds of Northern North America : 227–239. Wildlife Research Report 11. Fish & Wildlife Service, Washington DC.

Kuschert, H., von Ekelöf, H. O. & Fleet, D. M. 1981. Neue Kriterien zur Altersbestimmung der Trottellumme (Uria aalge) und des Tordalken (Alca torda). Seevögel 2: 58–61.

Lagring, R., Degraer, S., de Montpellier, G., Jacques, T., Van Roy, W. & Schallier, R. 2012. Twenty years of Belgian North Sea aerial surveillance: a quantitative analysis of results confirms effectiveness of international oil pollution legislation. Marine Pollution Bulletin 64: 644–652. [Crossref]

Larminie, F. G., Clark, R. B., Rudd, J. K. & Tasker, M. L. 1987. The history and future of North Sea oil and gas: an environmental perspective. Philosophical Transactions of the Royal Society of London B 316: 487–493. [Crossref]

Leopold, M. F., Kik, M., van Tulden, P., van Franeker, J. A., Kühn, S. & Rijks, J. 2019. De Zoe en de zeekoet: Een onderzoek naar de doodsoorzaak en de herkomst van de zeekoeten die massaal strandden op de Nederlandse kust in januari en februari 2019. Unpublished Research Report C026/19. Wageningen Marine Research, Den Helder. [Crossref]

Maas, F. J. 1983. Leeftijdsbepaling en ondersoorten bij de Alk Alca torda. Nieuwsbrief NSO 4: 61–65.

Mackay, N. 2016. North Sea oil industry under fire as spills rise. ( Sunday Herald. Accessed March 2021.

Mitchell, R., Langslow, D. R., Blake, B. F., Jones, P. H., Dixon, T. & Tasker, M. L. 1980. Investigation of the distribution of seabirds at sea: first annual report, November 1979 to November 1980. Nature Conservancy Council, Aberdeen.

Mörzer Bruijns, M. F. 1959. Stookolievogels op de Nederlandse kust. De Levende Natuur 62: 172–178.

Mudge, G. P. & Aspinall, S. J. 1985. Seabird studies in East Caithness, summer 1985. Royal Society for the Protection of Birds, Sandy.

National Research Council (NRC) 1985. Oil in the Sea: Inputs, Fates and Effects. National Academies Press, Washington DC.

Nye, S. M., Bellamy, D. J. & Holden, M. J. 1973. Resource map of the North Sea: a first attempt. In: Goldberg, E. D. (ed.), North Sea Science: 481–485. MIT Press, Cambridge, MA.

OSPAR & Camphuysen, C. J. 2005. Background Document on the Ecological Quality Objective on Oiled Guillemots. North Sea Pilot Project on Ecological Quality Objectives, Biodiversity Series. OSPAR publication number: 2005/252.

OSPAR Commission 2009. EcoQO handbook for the application of Ecological Quality Objectives in the North Sea, second edition. EcoQO Handbook, OSPAR Commission, Oslo

OSPAR Commission 2010. OSPAR Commission 2010. Regional Implementation Framework for the EU Marine Strategy Framework Directive, MSFD Road Map. OSPAR publication no. 501/2010.

Ouwehand, J., Leopold, M. F. & Camphuysen, C. J. 2005. A comparative study of the diet of Guillemots Uria aalge and Razorbills Alca torda killed during the Tricolor oil incident in the south-eastern North Sea in January 2003. Atlantic Seabirds 6: 147–164.

Parslow, J. L. F. 1966. Oil pollution survey. British Birds 59: 390–392. [Crossref]

Perrins, C. 1969. Rehabilitation of Oiled Seabirds: A Report to the Advisory Committee on Oil Pollution of the Sea. By R. B. Clark & R. J. Kennedy. [Book review]. British Birds 62: 241–242.

Reineking, B. & Vauk, G. 1982. Seevögel: Opfer der Ölpest. Jordsandbuch Nr 2. Herausgegeben vom Verein Jordsand zum Schutz der Seevögel e.V, Otterndorf.

Reynolds, T. J., Harris, M. P., King, R., Swann, R. L., Jardine, D. C., Frederiksen, M. & Wanless, S. 2011. Among-colony synchrony in the survival of Common Guillemots Uria aalge reflects shared wintering areas. Ibis 153: 818–831. [Crossref]

Richardson, M. G., Heubeck, M., Lea, D. & Reynolds, P. 1982. Oil pollution, seabirds, and operational consequences, around the northern isles of Scotland. Environmental Conservation 9: 315–321. [Crossref]

Sandee, H. 1983. Kleurcontrast in de vleugeldekveren bij Alk en Zeekoet. Nieuwsbrief NSO 4: 133–143.

Stienen, E. W. M., Haelters, J., Kerckhof, F. & van Waeyenberge, J. 2004. Three colours of black: seabird strandings in Belgium during the Tricolor incident. Atlantic Seabirds 6: 129–146.

Stone, C. J., Webb, A., Barton, C., Ratcliffe, N., Reed, T. C., Tasker, M. L., Camphuysen, C. J. & Pienkowski, M. W. 1995. An atlas of seabird distribution in north-west European waters. Joint Nature Conservation Committee, Peterborough.

Swennen, C. & Spaans, A. L. 1970. De sterfte van zeevogels door olie in februari 1969 in het Waddengebied. Het Vogeljaar 18: 233–245.

Tanis, J. J. C. & Mörzer Bruijns, M. F. 1962. Het onderzoek naar stookolievogels van 1958–1962. De Levende Natuur 65: 133–140.

Tromp, J. 1927. Teervogels. Het Vaderland: staat – en letterkundig nieuwsblad 28 January 1927.

Verwey, J. 1915. De Trekvogels, de Oorlog en nog wat. De Levende Natuur 20: 20.

Verwey, J. 1922. The moult of Uria troille (L.) and Alca torda (L.). Ardea 11: 99–116.

Verwey, J. 1923. De rui van Uria troille (L.). Ardea 12: 31–336.

Verwey, J. 1927a. On the movements of the southern and northern Guillemots off the Dutch coast. Ardea 16: 32–35.

Verwey, J. 1927b. Geslechtsreife und Prachtkleid der Vögel II. Zwischenkleid von Uria aalge (L.). Zoologischer Anzeiger Leipzig 71: 1–4.

Votier, S. C., Hatchwell, B. J., Beckerman, A., McCleery, R. H., Hunter, F. M., Pellatt, J., Trinder, M. & Birkhead, T. R. 2005. Oil pollution and climate have wide-scale impacts on seabird demographics. Ecology Letters 8: 1157–1164. [Crossref]

Wardley-Smith, J. 1976. The Control of Oil Pollution on the Sea and Inland Waters. Graham & Trotman, London.

Westhoff, V. 1936. Teerslachtoffers. Amoeba 15: 27.

de Wijs, W. J. R. 1981. Uria aalge hyperborea in Nederland? Limosa 54: 63–64.

de Wijs, W. J. R. 1985. Herkomst en leeftijd van Zeekoeten Uria aalge in Nederland. Limosa 58: 61–64.

Witherby, H. F. 1923. Notes on the Common Guillemot, a new British form. British Birds 16: 323–324.

Witherby, H. F. 1926. On the distribution of the Southern and Northern Guillemots, in Great Britain. British Birds 19: 274.

Witherby, H. F., Jourdain, F. C. R., Ticehurst, N. F. & Tucker, B. W. 1952. The Handbook of British Birds, 5. Seventh impression, H. F. & G. Witherby, London.

Wolfe, D. A. 1985. Fossil fuels: transportation and marine pollution. In: Duedall, I. W., Kester, D. A., Park, P. H. & Ketchum, B. H. (eds.), Wastes in the Ocean, 4: 45–94. Wiley-Interscience, Hoboken, New Jersey.

Woltman, D. 1920. Olie en vogels. De Levende Natuur 25: 61.

Zoest, R. van Verduin, E. & Visser, A. 2011. Het aantal olievlekken op de Noordzee daalt. Nieuwsbrief Integraal Beheer Noordzee 2011: 4.