Contributors and references


Karin Hårding, Britt-Marie Bäcklin, Charlotta Moraeus, Kaarina Kauhala, Ursula Siebert, Tina Kesselring, Sacha Viquerat, Lena Avellan and Tero Härkönen



This version of the HELCOM core indicator report was published in July 2018:

Reproductive status of seals HELCOM core indicator 2018 (pdf)

Older versions of the core indicator report are available:

Core indicator report – web-based version December 2015 (pdf)

Extended core indicator report – outcome of CORESET II project (pdf)

2013 Indicator report (pdf)



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Harding, K.C., Härkönen, T., Helander, B., Karlsson, O. (2007) Status of Baltic grey seals: Population assessment and risk analysis. NAMMCO Scientific Publications 6: 33-56.

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Härkönen, T., Harding, K.C., Goodman, S., Johannesson, K. (2005) Colonization history of the Baltic harbor seals: Integrating archaeological, behavioural and genetic data. Marine Mammal Science 21: 695-716.

Harkonen, T., Bäcklin, B-M., Barrett, T., Anders Bergman, A., Corteyn, M., Dietz, R., Harding, K., Malmsten, J., Roos, A., Teilmann, T. (2008) Mass mortality in harbour seals and harbour porpoises caused by an unknown pathogen. The Veterinary Record 162: 555-556.

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Additional relevant publications

Bäcklin, B.-M., Moraeus, C., Kauhala, K., Isomursu. M. (2013) Pregnancy rates of the marine mammals - Particular emphasis on Baltic grey and ringed seals. HELCOM web portal.

Caswell, H. (2001) Matrix population models: Construction, analysis, and interpretation. Second edition. Sinauer, Sunderland. Massachusetts, USA.

Dietz, R., Heide-Jørgensen, M.-P., Härkönen, T. (1989) Mass deaths of harbour seals Phoca vitulina in Europe. Ambio 18(5): 258-264.

Galatius, A., Ahola, M., Härkönen, T., Jüssi, I., Jüssi, M., Karlsson, O., Verevkin, M. (2014) Guidelines for seal abundance monitoring in the HELCOM area 2014. Availabe at:

Harding, K.C., Härkönen, T., Caswell, H. (2002) The 2002 European seal plague: epidemiology and population consequences. Ecology Letters 5: 727-732.

Harding, K.C., Härkönen, T., Pineda, J. (2003) Estimating quasi-extinction risk of European harbour seals: a reply to Lonergan and Harwood. Ecology Letters 6: 894-897.

Härkönen, T., Lunneryd, S.G. (1992) Estimating abundance of ringed seals in the Bothnian Bay. Ambio 21: 497-510.

Härkönen, T., Stenman, O., Jüssi, M., Jüssi, I., Sagitov, R., Verevkin, M. (1998) Population size and distribution of the Baltic ringed seal (Phoca hispida botnica). In: Ringed Seals (Phoca hispida) in the North Atlantic. Edited by C.Lydersen and M.P. Heide-Jørgensen. NAMMCO Scientific Publications 1: 167-180.

Härkönen, T., Dietz, R., Reijnders, P., Teilmann, J., Harding, K., Hall, A., Brasseur, S., Siebert, U., Goodman, S., Jepson, P., Dau Rasmussen, T., Thompson, P. (2006) A review of the 1988 and 2002 phocine distemper virus epidemics in European harbour seals. Diseases of Aquatic Organisms 68: 115-130.

Härkönen, T., Brasseur, S., Teilmann, J., Vincent, C., Dietz, R., Reijnders, P., Abt, K. (2007) Status of grey seals along mainland Europe, from the Baltic to France. NAMMCO Scientific Publications 6: 57-68.

Härkönen, T., Harding, K., Rasmussen, T.D., Teilmann, J., Dietz, R. (2007) Age- and Sex-specific Mortality Patterns in an Emerging Wildlife Epidemic: the Phocine Distemper in European Harbour Seals. PLoS ONE 2(9): e887. doi: 10.1371/journal.pone.0000887.

Harkonen, T., Harding, K.C.  (2011) Predicting recurrent PDV epidemics in European harbour seals. NAMMCO Scientific Publications 8: 275-284.

Harwood, J., Prime, J.H. (1978) Some factors affecting the size of British grey seal populations. Journal of Applied Ecology 401-411.

Heide-Jørgensen, M.-P., Härkönen, T. (1992) Epizootiology of seal disease. J. Appl. Ecol. 29: 99-107.

Hiby, L. et al. (2013) Estimates of the size of the Baltic grey seal population based on photo-identification data. NAMMCO Scientific Publications [S.l.] 6: 163-175. Oct. 2013. ISSN 2309-2491. Available at: <>. Doi:

Jüssi, M., Härkönen, T., Jüssi, I. Helle, E. (2008) Decreasing ice coverage will reduce the reproductive success of Baltic grey seal (Halichoerus grypus) females. Ambio 37: 80–85.

Karlsson, O., Härkönen, T., Bäcklin, B.-M. (2008) Populationer på tillväxt. Havet, 2008: 91-92.

Kauhala, K., Ahola, M. & Kunnasranta, M. 2014. Decline in the pregnancy rate of Baltic grey seal females during the 2000s, estimated with different methods. – Annales Zoologici Fennici 51: 313-324.

Kokko, H. Helle, E, J., Ranta E., Sipilä, T. (1999) Backcasting population sizes of ringed and grey seals in the Baltic and Lake Saimaa during the 20th century.  Annales Zoologici Fennici 36: 65-73

Meier, H.E.M., Döscher, R., Halkka, A. (2004) Simulated distributions of Baltic Sea-ice in the warming climate and consequences for the winter habitat of the Baltic Ringed Seal. Ambio 33: 249–256.

Mortensen, P., Bergman, A., Bignert, A., Hansen, H.J., Härkönen, T., Olsson, M. (1992) Prevalence of skull lesions in harbour seals Phoca vitulina in Swedish and Danish museum collections during the period 1835-1988. Ambio 21: 520-524.

Olsen, M.T., Andersen, S.M., Teilmann, J. Dietz, R., Harkonen, T. (2011) Status of the harbour seal in Southern Scandinavia. NAMMCO Scientific Publications 8: 77-94.

Palo, J.U., Mäkinen, H.S., Helle, E., Stenman, O., Väinölä, R. (2001) Microsatellite variation in ringed seals (Phoca hispida): genetic structure and history of the Baltic Sea population. Heredity 86: 609–617. doi: 10.1046/j.1365-2540.2001.00859.x.

Teilmann, J., Riget, F., Harkonen, T. (2010) Optimising survey design in Scandinavian harbour seals: Population trend as an ecological quality element. ICES Journal of Marine Science 67: 952–958.

Sipilä, T. (2003) Conservation biology of Saimaa ringed seal (Phoca hispida saimensis) with reference to other European seal populations. PhD Thesis. Available at:

Stenman, O., Halkka, A., Helle, E., Keränen, S., Nummelin, J., Soikkeli, M., ... Tanskanen, A. (2005) Numbers and occurrence of grey seals in the Finnish sea area in the years 1970-2004. In Symposium on Biology and Management of Seals in the Baltic area. Kala-ja riistaraportteja (346): 58-61.

Svensson, C.J., Hansson, A., Harkonen, T., Harding, K. (2011) Detecting density dependence in growing seal populations. Ambio (2011) 40: 52–59. DOI 10.1007/s13280-010-0091-7.

Sundqvist, L., Harkonen, T., Svensson, C.J., Harding, K.C. (2012) Linking climate trends to population dynamics in the Baltic ringed seal - Impacts of historical and future winter temperatures. Ambio. DOI 10.1007/s13280-012-0334-x.

Vanhatalo, J., Vetemaa, M., Herrero, A., Aho, T., Tiilikainen, R. (2014) By-Catch of Grey Seals (Halichoerus grypus) in Baltic Fisheries—A Bayesian Analysis of Interview Survey. PLoS ONE 9(11): e113836. doi:10.1371/journal.pone.0113836.

Zohari, S., Neimanis, A., Härkönen, T., Moraeus, C., Valarcher, J.F. (2014) Avian influenza A(H10N7) virus involvement in mass mortality of harbour seals (Phoca vitulina) in Sweden, March through October 2014. Euro Surveill. 19(46): pii=20967. Available at:



HELCOM core indicator report,

ISSN 2343-2543