P. Reijnders and K. Lankester, Status of marine mammals in the North sea, Netherlands Journal of Sea Research, vol.26, issue.2-4, pp.2-4427, 1990.
DOI : 10.1016/0077-7579(90)90098-2

G. Power and J. Gregoire, Predation by Freshwater Seals on the Fish Community of Lower Seal Lake, Quebec, Journal of the Fisheries Research Board of Canada, vol.35, issue.6, pp.844-50, 1978.
DOI : 10.1139/f78-135

J. Estes, -Strategists?, Journal of the Fisheries Research Board of Canada, vol.36, issue.8, pp.1009-1026, 1979.
DOI : 10.1139/f79-140
URL : https://hal.archives-ouvertes.fr/inserm-00723650

W. Bowen, Role of marine mammals in aquatic ecosystems, Marine Ecology Progress Series, vol.158, pp.267-74, 1997.
DOI : 10.3354/meps158267

V. Lesage, M. Hammill, and K. Kovacs, Marine mammals and the community structure of the Estuary and Gulf of St Lawrence, Canada: evidence from stable isotope analysis, Marine Ecology Progress Series, vol.210, pp.203-224, 2001.
DOI : 10.3354/meps210203

J. Tougaard, I. Ebbesen, S. Tougaard, T. J. Teilmann, and J. , Satellite tracking of harbour seals on Horns Reef Technical report to Techwise A/S, Biological Papers from the Fisheries and Maritime Museum Available: http://www.ens.dk/sites/ens.dk/files/supply/renewable-energy, 2003.

P. Reijnders, S. Brasseur, T. Borchardt, K. Camphuysen, R. Czeck et al., Marine mammals Trilateral Monitoring and Assessment Group, Thematic Report N°20. In: Marencic H and Vlas J de Quality status report 2009. Wadden Sea Ecosystem N°25. Wadden Sea Secretariat, 2009.

R. Smardon, The Wadden Sea Wetlands: A multi-juridictional Challenge Sustaining the World´s Wetlands?Setting Policy and Resolving Conflicts. College of Environmental Science and Foresty, pp.21-54, 2009.

H. Lotze, K. Reise, B. Worm, J. Van-beusekom, M. Busch et al., Human transformations of the Wadden Sea ecosystem through time: a synthesis, Helgoland Marine Research, vol.84, issue.Suppl, pp.84-95, 2005.
DOI : 10.1007/s10152-004-0209-z

M. Hoffmann, J. Belant, J. Chanson, N. Cox, J. Lamoreux et al., The changing fates of the world's mammals, Philosophical Transactions of the Royal Society B: Biological Sciences, vol.328, issue.5975, pp.2598-610, 1578.
DOI : 10.1126/science.1188606

P. Reijnders, E. Ries, S. Tougaard, N. Nørgaard, G. Heidemann et al., Population development of harbour seals Phoca vitulina in the Wadden Sea after the 1988 virus epizootic, Journal of Sea Research, vol.38, issue.1-2, pp.161-169, 1997.
DOI : 10.1016/S1385-1101(97)00031-2

P. Reijnders, S. Brasseur, and E. Meesters, Earlier pupping in harbour seals, Phoca vitulina. Biologie Letters

S. Brasseur, B. Diederichs, R. Czeck, L. Jensen, A. Galatius et al., Aerial surveys of Harbour Seals in the Wadden Sea in 2013?Is the population growth rate slowing down? 2013 Available: http:// www.waddensea-secretariat.org/sites

A. Galatius, S. Brasseur, R. Czeck, B. Diederichs, L. Jensen et al., Aerial surveys of Harbour Seals in the Wadden Sea in 2014?The highest pup count recorded yet Available: http://www. waddensea-secretariat.org/sites, 2014.

N. Osinga, I. Pen, U. De-haes, H. Brakefield, and P. , Evidence for a progressively earlier pupping season of the common seal (Phoca vitulina) in the Wadden Sea, Journal of the Marine Biological Association of the United Kingdom, vol.13, issue.08, pp.1663-1671, 2012.
DOI : 10.1139/z91-162

H. Drescher and . Biology, ecology and conservation of harbour seals in the tidelands of Schleswig-Holstein, Beitr Wildbiol, vol.1, pp.1-73, 1979.

G. Behrends and . Zur-nahrungswahl-von-seehunden, Phoca vitulina L.) im Wattenmeer Schleswig-Holsteins, Zeitschrift für Jagdwissenschaft, vol.31, issue.1, pp.3-14, 1985.

U. Sievers, Stomach content analysis in the harbour seal (Phoca vitulina) from the Schleswig-Holstein Waddensea, Zool Anz, vol.222, issue.56, pp.249-60, 1989.

T. Härkönen and M. Heide-jørgensen, as a predator in the Skagerrak, Ophelia, vol.60, issue.3, pp.191-207, 1991.
DOI : 10.1080/00785326.1986.10429749

T. Härkönen, , in the Skagerrak and the Kattegat, Journal of Zoology, vol.169, issue.3, pp.535-578, 1987.
DOI : 10.1111/j.1469-7998.1987.tb03724.x

E. Brown and G. Pierce, Monthly variation in the diet of harbour seals in inshore waters along the southeast Shetland (UK) coastline, Marine Ecology Progress Series, vol.167, pp.275-89, 1998.
DOI : 10.3354/meps167275

A. Hall, J. Watkins, and P. Hammond, Seasonal variation in the diet of harbour seals in the south-western North Sea, Marine Ecology Progress Series, vol.170, pp.269-81, 1998.
DOI : 10.3354/meps170269

G. Pierce, P. Thompson, A. Miller, J. Diack, D. Miller et al., ) in the Moray Firth area of Scotland, Journal of Zoology, vol.27, issue.No. 82, pp.641-52, 1991.
DOI : 10.1111/j.1469-7998.1991.tb04393.x

P. Thompson, B. Mcconnell, D. Tollit, A. Mackay, C. Hunter et al., Comparative Distribution, Movements and Diet of Harbour and Grey Seals from Moray Firth, N. E. Scotland, The Journal of Applied Ecology, vol.33, issue.6, pp.1572-84, 1996.
DOI : 10.2307/2404795

D. Tollit, P. Thompson, and S. Greenstreet, , in relation to variations in prey abundance, Canadian Journal of Zoology, vol.75, issue.9, pp.1508-1526, 1997.
DOI : 10.1139/z97-774

P. Thompson, G. Pierce, J. Hislop, D. Miller, and J. Diack, Winter Foraging by Common Seals (Phoca vitulina) in Relation to Food Availability in the Inner Moray Firth, N.E. Scotland, The Journal of Animal Ecology, vol.60, issue.1, pp.283-94, 1991.
DOI : 10.2307/5460

A. Gilles, H. Andreasen, S. Müller, and U. Siebert, Nahrungsökölögie von marinen Säugetieren und Seevögeln für das Management von NATURA Available: https://www.bfn.de/ fileadmin, Gebieten. Endbericht für das Bundesamt für Naturschutz . Federal Agency for Nature Conservation, 2000.

S. Andersen, J. Teilmann, P. Harders, E. Hansen, and D. Hjollund, Diet of harbour seals and great cormorants in Limfjord, Denmark: interspecific competition and interaction with fishery, ICES Journal of Marine Science, vol.64, issue.6, pp.1235-1280, 2007.
DOI : 10.1093/icesjms/fsm092

P. Reijnders, K. Abt, S. Brasseur, K. Camphuysen, B. Reineking et al., Wadden Sea Ecosystem N°19 Available: http://www.waddensea-secretariat.org/sites, Wadden Sea Secretariat, pp.305-318, 2005.

K. Das, G. Lepoint, Y. Leroy, and J. Bouquegneau, Marine mammals from the southern North Sea: feeding ecology data from ? 13 C and ? 15 N measurements, Marine Ecology Progress Series, vol.2633354, pp.287-98, 2003.

K. Hobson, J. Sease, R. Merrick, and J. Piatt, INVESTIGATING TROPHIC RELATIONSHIPS OF PINNIPEDS IN ALASKA AND WASHINGTON USING STABLE ISOTOPE RATIOS OF NITROGEN AND CARBON, Marine Mammal Science, vol.2, issue.1, pp.114-146, 1997.
DOI : 10.1007/BF00379558

S. Caut, S. Laran, E. Garcia-hartmann, and K. Das, Stable isotopes of captive cetaceans (killer whales and bottlenose dolphins), Journal of Experimental Biology, vol.214, issue.4, pp.538-583, 2011.
DOI : 10.1242/jeb.045104

L. Tieszen, T. Boutton, K. Tesdahl, and N. Slade, Fractionation and turnover of stable carbon isotopes in animal tissues: Implications for ?13C analysis of diet, Oecologia, vol.37, issue.1-2, pp.32-39, 1983.
DOI : 10.1007/BF00379558

M. Deniro and S. Epstein, Influence of diet on the distribution of carbon isotopes in animals, Geochimica et Cosmochimica Acta, vol.42, issue.5, pp.495-5060016, 1978.
DOI : 10.1016/0016-7037(78)90199-0

G. Rau, A. Mearns, D. Young, R. Olson, H. Schafer et al., Animal C/C Correlates with Trophic Level in Pelagic Food Webs, Ecology, vol.64, issue.5, pp.1314-1322, 1983.
DOI : 10.2307/1937843

K. Hobson, J. Piatt, and J. Pitocchelli, Using Stable Isotopes to Determine Seabird Trophic Relationships, The Journal of Animal Ecology, vol.63, issue.4, pp.786-98, 1994.
DOI : 10.2307/5256

B. Peterson and B. Fry, Stable Isotopes in Ecosystem Studies, Annual Review of Ecology and Systematics, vol.18, issue.1, pp.293-320, 1987.
DOI : 10.1146/annurev.es.18.110187.001453

B. Fry, Food web structure on Georges Bank from stable C, N, and S isotopic compositions, Limnology and Oceanography, vol.33, issue.5, p.9, 1988.
DOI : 10.4319/lo.1988.33.5.1182

K. Hobson and H. Welch, Determination of trophic relationships within a high Arctic marine food web using ? 13 C and ? 15 N analysis, Marine Ecology Progress Series, vol.84, p.10, 1992.

S. Hall-aspland, T. Rogers, and R. Canfield, Stable carbon and nitrogen isotope analysis reveals seasonal variation in the diet of leopard seals, Marine Ecology Progress Series, vol.305, issue.3354, pp.249-59, 2005.
DOI : 10.3354/meps305249

Y. Cherel, L. Kernaléguen, P. Richard, and C. Guinet, Whisker isotopic signature depicts migration patterns and multi-year intra- and inter-individual foraging strategies in fur seals, Biology Letters, vol.13, issue.5, pp.830-832, 2009.
DOI : 10.1016/j.tree.2004.03.017
URL : https://hal.archives-ouvertes.fr/hal-00528653

C. Newland, I. Field, Y. Cherel, C. Guinet, C. Bradshaw et al., Diet of juvenile southern elephant seals reappraised by stable isotopes in whiskers, Marine Ecology Progress Series, vol.424, pp.247-58, 2011.
DOI : 10.3354/meps08769
URL : https://hal.archives-ouvertes.fr/hal-00573179

K. Hobson, D. Schell, D. Renouf, and E. Noseworthy, Stable carbon and nitrogen isotopic fractionation between diet and tissues of captive seals: implications for dietary reconstructions involving marine mammals, Canadian Journal of Fisheries and Aquatic Sciences, vol.53, issue.3, pp.528-561, 1996.
DOI : 10.1139/f95-209

S. Newsome, M. Tinker, D. Monson, O. Oftedal, K. Ralls et al., ), Ecology, vol.94, issue.4, pp.961-7405, 2009.
DOI : 10.3354/meps281267

L. Zhao and D. Schell, Stable isotope ratios in harbor seal Phoca vitulina vibrissae: effects of growth patterns on ecological records, Marine Ecology Progress Series, vol.281, pp.267-73, 2004.
DOI : 10.3354/meps281267

B. Convention, C. Council-of-europe, and . No, Convention on the Conservation of European Wildlife and Natural Habitats. Annex III: Protected fauna species Available: http://conventions.coe.int/ Treaty, 1985.

H. Benke, U. Siebert, R. Lick, B. Bandomir, and R. Weiss, The current status of harbour porpoises (Phocoena phocoena) in German waters, Arch Fish Mar Res, vol.46, pp.97-123, 1998.

P. Martens and B. Jeev, Zooplankton response to a warmer northern Wadden Sea, Helgoland Marine Research, vol.58, issue.6, pp.67-75, 2008.
DOI : 10.1007/s10152-007-0097-0

L. Jensen, Monitoring of the seal population in the Wadden Sea in 2015?Monitering af saelbestanden i Vadehavet 2015, p.2015

M. Pockberger, Abiotic and biotic impacts on fish in the Wadden Sea Evaluating the effect of large scale climate oscillations, local ecosystem characteristics and invasive species: Doctoral dissertation, The Christian Albrecht University of Kiel, Available, vol.2015

F. Kellnreitner, The trophic structure of a Wadden Sea fish community and its feeding interactions with alien species: Doctoral dissertation, The Christian Albrecht University of Kiel, Available, vol.2012

U. Siebert, P. Wohlsein, K. Lehnert, and W. Baumgärtner, Pathological Findings in Harbour Seals (Phoca vitulina): 1996???2005, Journal of Comparative Pathology, vol.137, issue.1, pp.47-58, 2005.
DOI : 10.1016/j.jcpa.2007.04.018

J. Pinnegar and N. Polunin, Differential fractionation of delta13C and delta15N among fish tissues: implications for the study of trophic interactions, Functional Ecology, vol.13, issue.2, pp.225-256, 1999.
DOI : 10.1139/cjfas-54-5-1142

S. Bunn, N. Loneragan, and M. Kempster, Effects of acid washing on stable isotope ratios of C and N in penaid shrimp and seagrass: Implications for food web studies using multiple stable isotopes, Limnology and Oceanography, vol.40, issue.3, p.4, 1995.

R. Froese and P. D. , Data Base: FishBase [Internet], 2014.

C. Oh, R. Hartnoll, and R. Nash, Feeding ecology of the common shrimp Crangon crangon in Port Erin Bay, Isle of Man, Irish Sea, Marine Ecology Progress Series, vol.214, pp.211-234, 2001.
DOI : 10.3354/meps214211

V. Lesage, Trophic relationships, seasonal diving activity and movements of harbour seals, Phoca vitulina concolor, in the St Lawrence River estuary, Canada.: Doctoral dissertation, The University of Waterloo Available: https, 1999.

H. Bocherens, M. Fogel, N. Tuross, and M. Zeder, Trophic Structure and Climatic Information From Isotopic Signatures in Pleistocene Cave Fauna of Southern England, Journal of Archaeological Science, vol.22, issue.2, pp.327-400035, 1995.
DOI : 10.1006/jasc.1995.0035

K. Hobson and J. Sease, STABLE ISOTOPE ANALYSES OF TOOTH ANNULI REVEAL TEMPORAL DIETARY RECORDS: AN EXAMPLE USING STELLER SEA LIONS, Marine Mammal Science, vol.238, issue.1, pp.116-145, 1998.
DOI : 10.1016/0016-7037(84)90091-7

S. Jenkins, S. Partridge, T. Stephenson, S. Farley, and C. Robbins, Nitrogen and carbon isotope fractionation between mothers, neonates, and nursing offspring, Oecologia, vol.129, issue.3, pp.336-377, 2001.
DOI : 10.1007/s004420100755

S. Newsome, P. Koch, M. Etnier, and D. Aurioles-gamboa, USING CARBON AND NITROGEN ISOTOPE VALUES TO INVESTIGATE MATERNAL STRATEGIES IN NORTHEAST PACIFIC OTARIIDS, Marine Mammal Science, vol.78, issue.3, pp.556-72, 2006.
DOI : 10.1006/jasc.1998.0351

S. Polischuk, K. Hobson, and M. Ramsay, Use of stable-carbon and -nitrogen isotopes to assess weaning and fasting in female polar bears and their cubs, Canadian Journal of Zoology, vol.79, issue.3, pp.499-511, 2001.
DOI : 10.1139/z01-007

A. Parnell, R. I. Bearhop, S. Jackson, and A. , Source partioning using stable isotopes: coping with too much variation, PLoS ONE, vol.5, issue.3, p.1, 2010.

W. Edwards, H. Lindman, and L. Savage, Bayesian statistical inference for psychological research., Psychological Review, vol.70, issue.3, pp.193-242, 1963.
DOI : 10.1037/h0044139

N. Daan, P. Bromley, J. Hislop, and N. Nielsen, Ecology of North Sea fish, Netherlands Journal of Sea Research, vol.26, issue.2-4, pp.2-4343, 1990.
DOI : 10.1016/0077-7579(90)90096-Y

P. Polte and H. Asmus, Intertidal seagrass beds (Zostera noltii) as spawning grounds for transient fishes in the Wadden Sea. Marine ecology-progress series, pp.235-278, 2006.

I. Tulp, L. Bolle, and A. Rijnsdorp, Signals from the shallows: In search of common patterns in long-term trends in Dutch estuarine and coastal fish, Journal of Sea Research, vol.60, issue.1-2, pp.54-73, 2008.
DOI : 10.1016/j.seares.2008.04.004

H. Baumann, A. Malzahn, R. Voss, and A. Temming, The German Bight (North Sea) is a nursery area for both locally and externally produced sprat juveniles, Journal of Sea Research, vol.61, issue.4, pp.234-277, 2009.
DOI : 10.1016/j.seares.2009.01.004

M. Dickey-collas, L. Bolle, J. Van-beek, and P. Erftemeijer, Variability in transport of fish eggs and larvae. II. Effects of hydrodynamics on the transport of Downs herring larvae, Marine Ecology Progress Series, vol.390, pp.183-94, 2009.
DOI : 10.3354/meps08172

A. Del-norte-campos and A. Temming, Daily activity, feeding and rations in gobies and brown shrimp in the northern Wadden Sea, Marine Ecology Progress Series, vol.115, p.13, 1994.
DOI : 10.3354/meps115041

K. Mahé, J. Delpech, and A. Carpentier, Synthèse bibliographique des principales espèces de Manche orientale et du golfe de Gascogne. Centre Manche-mer du Nord. Département Halieutique. Laboratoire Ressources Halieutiques de Boulogne sur mer: Convention Ifremer-Ministère de l'Industrie, 2006.

J. Luksenburg, T. Pedersen, and I. Falk-petersen, Reproduction of the shorthorn sculpin Myoxocephalus scorpius in northern Norway, Journal of Sea Research, vol.51, issue.2, pp.157-66, 2004.
DOI : 10.1016/j.seares.2003.09.001

H. Heessen, The Distribution of Cod (Gadus morhua) in the North Sea, NAFO Scientific Council Studies, vol.18, p.7, 1993.

G. Pierce, P. Boyle, L. Hastie, and M. Santos, Diets of squid Loligo forbesi and Loligo vulgaris in the northeast Atlantic, Fisheries Research, vol.21, issue.1-2, pp.149-630165, 1994.
DOI : 10.1016/0165-7836(94)90101-5

R. France, Carbon-13 enrichment in benthic compared to planktonic algae:foodweb implications, Marine Ecology Progress Series, vol.124, pp.307-319, 1995.
DOI : 10.3354/meps124307

R. Heckey and R. Hesslein, Contributions of Benthic Algae to Lake Food Webs as Revealed by Stable Isotope Analysis, Journal of the North American Benthological Society, vol.14, issue.4, pp.631-53, 1995.
DOI : 10.2307/1467546

J. Hislop, A. Robb, M. Bell, and D. Armstrong, The diet and food consumption of whiting (Merlangius merlangus) in the North Sea, ICES Journal of Marine Science, vol.48, issue.2, pp.139-56, 1991.
DOI : 10.1093/icesjms/48.2.139

A. Rijnsdorp and B. Vingerhoed, Feeding of plaice Pleuronectes platessa L. and sole Solea solea (L.) in relation to the effects of bottom trawling, Journal of Sea Research, vol.45, issue.3-4, pp.3-4219, 2001.
DOI : 10.1016/S1385-1101(01)00047-8

J. Navarro, M. Coll, C. Somes, and R. Olson, Trophic niche of squids: Insights from isotopic data in marine systems worldwide. Deep Sea Research Part II: Topical Studies in Oceanography, pp.93-102, 2013.

S. Jennings, J. Pinnegar, N. Polunin, and K. Warr, Linking size-based and trophic analyses of benthic community structure, Marine Ecology Progress Series, vol.226, pp.77-85, 2002.
DOI : 10.3354/meps226077

K. Hobson, Tracing origins and migration of wildlife using stable isotopes: a review, Oecologia, vol.120, issue.3, pp.314-340, 1999.
DOI : 10.1007/s004420050865

L. Loc-'h, F. Hily, C. Grall, and J. , Benthic community and food web structure on the continental shelf of the Bay of Biscay (North Eastern Atlantic) revealed by stable isotopes analysis, Journal of Marine Systems, vol.72, pp.1-417, 2008.

I. Berg, T. Haug, and K. Nilssen, Harbour Seal ( Phoca vitulina ) Diet in Vester??len, North Norway, Sarsia, vol.10, issue.6, pp.451-61, 2002.
DOI : 10.2307/3808110