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Mammal Research

, Volume 64, Issue 1, pp 109–120 | Cite as

Reproductive rate and nutritional status of Baltic ringed seals

  • Kaarina KauhalaEmail author
  • Mikaela Bergenius
  • Marja Isomursu
  • Jari Raitaniemi
Original Paper
  • 85 Downloads

Abstract

The Baltic ringed seal (Pusa hispida botnica) population started to increase in numbers in the 1990s after a population decrease caused by hunting and environment pollutants. The annual growth rate of this population is about 5%, while in a fast-growing seal population, it could be as high as 10–12%. The reasons behind the fairly slow population growth rate are not known. In the current study, we investigated reproductive rate and nutritional status of ringed seals in the Bothnian Bay, the largest subpopulation in the Baltic Sea. The aims of the present study were (1) to estimate reproductive rate of females and (2) to examine especially annual variation in nutritional status (blubber thickness) in relation to prey quality and quantity as it affects reproductive rate. The proportion of females with corpus albicans (an estimate of birth rate) in Baltic ringed seals has increased from low values since the late 1990s and is at present about 72%. It was highest among females at the age of 5–12 years and declined thereafter, especially after the age of 20. Uterine occlusions, which earlier caused sterility to females, were rare in recent years. Blubber thickness of both pups and older seals decreased during spring and increased during the rest of the year. Average blubber thickness of sub-adults and adults declined until the early 2000s and increased thereafter, except in adult females, and correlated positively especially with average weight of herring (Clupea harengus). In sub-adults, blubber thickness correlated also with the weight and catch size of vendace (Coregonus albula). These results suggest that the quality and quantity of important prey fish may affect the nutritional status of seals. In recent years, average blubber thickness of adult females in spring declined, although herring quality increased. This may be partly due to stress caused by poor ice conditions in the nursing period in late winter. The declining nutritional status of adult females may, at least partly, be responsible for the relatively low birth rate and population growth rate of ringed seals in the Bothnian Bay.

Keywords

Birth rate Body condition Herring Pusa hispida Vendace 

Notes

Acknowledgements

We are very grateful to Britt-Marie Bäcklin and Karin Harding for many valuable comments on the manuscript. We also wish to thank Mervi Kunnasranta, Charlotta Moraeus, and Petri Timonen who have helped to examine seal samples. Hunters and fishermen sent us samples from Finland and the Swedish Museum of Natural History provided seal data from Sweden. J. Vainio from the Finnish Meteorological Institute provided data of ice conditions.

Funding

KK was financed by BONUS BaltHealth. The BaltHealth project has received funding from BONUS (Art. 185), funded jointly by the EU, Innovation Fund Denmark (grants 6180-00001B and 6180-00002B), Forschungszentrum Jülich GmbH, German Federal Ministry of Education and Research (grant number FKZ 03F0767A), Academy of Finland (decision #311966) and Swedish Foundation for Strategic Environmental Research.

References

  1. Bergman A (1999) Health condition of the Baltic grey seal (Halichoerus grypus) during two decades. Gynaecological health improvement but increased prevalence of colonic ulcers. APMIS 107:270–282CrossRefGoogle Scholar
  2. Bergman A, Järplid B, Svensson BM (1990) Pathological findings indicative of distember in European seals. Vet Microbiol 23:331–341CrossRefGoogle Scholar
  3. Bowen WD, Iverson SJ, McMillan JI, Boness DJ (2006) Reproductive performance in grey seals: age related improvement and senescence in a capital breeder. J Anim Ecol 75:1340–1351CrossRefGoogle Scholar
  4. Bowen WD, Heyer CE, McMillan JI, Iverson SI (2015) Offspring size at weaning affects survival to recruitment and reproductive performance of primiparous gray seals. Ecol Evol 5:1412–1424CrossRefGoogle Scholar
  5. Bowen WD, Read AJ, Estes JA (2002) Feeding ecology. In: Hoelzel AR (ed) Marine mammal biology, an evolutionary approach. Blackwell Publishing, OxfordGoogle Scholar
  6. Boyd IL (1984) The relationship between body condition and the timing of implantation in pregnant Grey seals (Halichoerus grypus). J Zool 203:113–123CrossRefGoogle Scholar
  7. Boyd IL, Lockyer C, Marsh HD (1999) Reproduction in marine mammals. In: Reynolds JE, Rommel SA (eds) Biology of marine mammals. Smithsonian Institution Press, WashingtonGoogle Scholar
  8. Burek KA, Guland FMD, O’Hara TM (2008) Effects of climate change on arctic marine mammal health. Ecol Appl 18:S126–S134CrossRefGoogle Scholar
  9. Bäcklin BM, Moraeus C, Roos A, Eklöf E, Lind Y (2011) Health and age and sex distributions of Baltic grey seals (Halichoerus grypus) collected from bycatch and hunt in the Gulf of Bothnia. ICES J Mar Sci 68:183–188CrossRefGoogle Scholar
  10. Bøhn T, Amundsen PA (1998) Effects of invading vendace (Coregonus albula L.) on species composition and body size in two zooplankton communities of the Pasvik River system, northern Norway. J Plankton Res 20:243–256CrossRefGoogle Scholar
  11. Durbin J, Watson GS (1951) Testing for serial correlation in least squares regression, II. Biometrika 38:159–179CrossRefGoogle Scholar
  12. Fedak MA, Anderson SS (1982) The energetics of lactation: accurate measurements from a large wild mammal, the Grey seal (Halichoerus grypus). J Zool 198:473–479CrossRefGoogle Scholar
  13. Fedoseev GA (1975) Ecotypes of the ringed seal (Pusa hispida Schreber, 1777) and their reproductive capabilities. Rapport P-v Réun Cons Int Explor Mer 169:156–160Google Scholar
  14. Ferguson SH, Brent GY, Yurkowski DJ, Anderson R, Willing C, Nielsen O (2017) Demographic, ecological, and physiological responses of ringed seals to an abrupt decline in sea ice availability. PeerJ 5:e2957.  https://doi.org/10.7717/peerj.2957 CrossRefGoogle Scholar
  15. Ferguson SH, Stirling I, McLoughlin P (2005) Climate change and ringed seal (Phoca hispida) recruitment in Western Hudson Bay. Mar Mamm Sci 21:121–135CrossRefGoogle Scholar
  16. Hall AJ, McConnell BJ, Barker RJ (2001) Factors affecting first-year survival in grey seals and their implications for life history strategy. J Anim Ecol 70:138–149CrossRefGoogle Scholar
  17. Hammill MO (1987) Ecology of the ringed seal (Phoca hispida Schreber) in the fast-ice of Barrow Strait, Nortwest Territories. Ph.D. thesis, Department of Renewable Resources, Macdonald College of McGill University, Montreal, CanadaGoogle Scholar
  18. Hammill MO, Kingsley MCS, Beck GG, Smith TG (1995) Growth and condition in the Northwest Atlantic harp seal. Can J Fish Aquat Sci 52:478–488CrossRefGoogle Scholar
  19. Hammill MO, Lydersen C, Ryg M, Smith TG (1991) Lactation in the ringed seal (Phoca hispida). Can J Fish Aquat Sci 48:2471–2476CrossRefGoogle Scholar
  20. Harding KC, Härkönen TJ (1999) Development in the Baltic grey seal (Halichoerus grypus) and ringed seal (Phoca hispida) populations during the 20th century. Ambio 28:619–627Google Scholar
  21. Harding KC, Fujiwara M, Axberg Y, Härkönen T (2005) Mass-dependent energetics and survival in harbour seal pups. Funct Ecol 19:129–135CrossRefGoogle Scholar
  22. Harding KC, Härkönen T, Helander B, Karlsson O (2007) Status of Baltic grey seals: population assessment and risk analysis. Nammco Sci Publ:33–56 No. 81986
  23. Harwood LA, Smith TG, Melling H (2000) Variation in reproduction and body condition of the ringed seal (Phoca hispida) in Western Prince Albert Sound, NT, Canada, as assessed through harvest-based sampling program. Arctic 53:422–431CrossRefGoogle Scholar
  24. Harwood LA, Smith TG, George JC, Sandstrom SJ, Walkusz W, Divoky DJ (2015) Change in the Beaufort Sea ecosystem: diverging trends in body condition and/or production in five marine vertebrate species. Prog Oceanogr 136:263–273CrossRefGoogle Scholar
  25. HELCOM (2015c). Nutritional status of marine mammals. HELCOM core indicator report. Online. http://www.helcom.fi/Core%20Indicators/Nutritional%20status%20of%20marine%20mammals_HELCOM%20core%20indicator%20report%202015_web%20version.pdfGoogle Scholar
  26. Helle E (1979) Structure and number of seal populations in the northern Baltic Sea: a study based on Finnish bounty statistics, 1956-1975. Aquilo Ser Zool 19Google Scholar
  27. Helle E (1980) Lowered reproductive capacity in female ringed seals (Pusa hispida) in the Bothnian Bay, northern Baltic Sea, with special reference to uterine occlusions. Ann Zool Fennici 17:147–158Google Scholar
  28. Helle E (1983) Hylkeiden elämää [Life of seals]. Helsinki, Kirjayhtymä [In Finnish]Google Scholar
  29. Helle E (1996) Norppa [ringed seal]. In: Lindén H, Hario M, Wikman M (eds) Riistan jäljille. Riista- ja kalatalouden tutkimuslaitos, Edita, Helsinki, pp 84–89Google Scholar
  30. Helle E, Olsson M, Jensen S (1976) PCB levels correlated with pathological changes in seal uteri. Ambio 5:261–262Google Scholar
  31. Hirvelä-Koski V, Nylund M, Skrzypczak T, Heikkinen P, Kauhala K, Jay M, Isomursu M (2017) Isolation of Brucella pinnipedialis from grey seals (Halichoerus grypus) in the Baltic Sea. J Wildl Dis 53:850–853CrossRefGoogle Scholar
  32. Holst M, Stirling I, Calvert W (1999) Age structure and reproductive rates of ringed seals (Phoca hispida) on the northwestern coast of Hudson Bay in 1991 and 1992. Mar Mamm Sci 15:1357–1364CrossRefGoogle Scholar
  33. 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). NAMMCO Sci Publ 1:167–180CrossRefGoogle Scholar
  34. ICES (2016) Report of the Baltic Fisheries Assessment Working Group (WGBFAS). ICES CM 2016/ACOM: 11Google Scholar
  35. Jüssi M, Härkönen T, Helle E, Jüssi I (2008) Decreasing ice coverage will reduce the breeding success of Baltic grey seal (Halichoerus grypus) females. Ambio 37:80–85CrossRefGoogle Scholar
  36. Kauhala K, Ahola M, Isomursu M, Raitaniemi J (2016) Impact of food resources, reproductive rate and hunting pressure on Baltic grey seal population in the Finnish sea area. Ann Zool Fennici 53:296–309CrossRefGoogle Scholar
  37. Kauhala K, Ahola M, Kunnasranta M (2014) Decline in the pregnancy rate of Baltic grey seal females during the 2000s, estimated with different methods. Ann Zool Fennici 51:313–324CrossRefGoogle Scholar
  38. Kauhala K, Bäcklin BM, Raitaniemi J, Harding KC (2017) The effect of prey quality and ice conditions on the nutritional status of Baltic gray seals of different age groups. Mammal Res 62:351–362CrossRefGoogle Scholar
  39. Kauhala K, Kunnasranta M, Valtonen M (2011) Hallien ravinto Suomen merialueella 2001–2007 – alustava selvitys [diet of grey seals in Finland in 2001–2007 – a preliminary study]. Suomen Riista 57:73–83 [In Finnish with English summary]Google Scholar
  40. Kjellqvist SA, Haug T, Øritsland T (1995) Trends in age-composition, growth and reproductive parameters of Barents Sea harp seals, Phoca groenlandica. ICES J Mar Sci 52:197–208CrossRefGoogle Scholar
  41. Kuosa H, Fleming-Lehtinen V, Lehtinen S, Lehtiniemi M, Nygård H, Raateoja M, Raitaniemi J, Tuimala J, Uusitalo L, Suikkanen S (2017) A retrospective view of the development of the Gulf of Bothnia ecosystem. J Mar Syst 167:78–92CrossRefGoogle Scholar
  42. Lavigne DM, Stewart REA, Fletcher F (1982) Changes in composition and energy content of harp seal milk during lactation. Physiol Zool 55:1–9CrossRefGoogle Scholar
  43. Liukko UM, Henttonen H, Hanski IK, Kauhala K, Kojola I, Kyheröinen EM, Pitkänen J (2015) Suomen nisäkkäiden uhanlaisuus 2015. 2015 red list of Finnish mammal species. Ympäristöministeriö ja Suomen ympäristökeskusGoogle Scholar
  44. Lundström K, Hjerne O, Alexandersson K, Karlsson O (2007) Estimation of grey seal (Halichoerus grypus) diet composition in the Baltic Sea. Nammco Sci Publ 6:177–196CrossRefGoogle Scholar
  45. Lundström K, Hjerne O, Lunneryd SG, Karlsson O (2010) Understanding the diet composition of marine mammals: grey seals (Halichoerus grypus) in the Baltic Sea. ICES J Mar Sci 67:1230–1239CrossRefGoogle Scholar
  46. Lunneryd SG (1997) By-catch of grey seal (Halichoerus grypus) in Swedish waters. ICES WG Seals and Small Cetaceans. WP.9Google Scholar
  47. Lydersen C, Kovacs KM (1999) Behaviour and energetics of ice-breeding, North Atlantic phocid seals during the lactation period. Mar Ecol Prog Ser 187:265–281CrossRefGoogle Scholar
  48. Mansfield AW (1991) Accuracy of age determination in the grey seal Halichoerus grypus of eastern Canada. Mar Mamm Sci 7:44–49CrossRefGoogle Scholar
  49. Mänttäri V (2011) Hallien (Halichoerus grypus) ja itämerennorppien (Phoca hispida botnica) ravinnonkäyttö Perämerellä [Diet of grey and ringed seals in the Bothnian Bay]. University of Jyväskylä, MS thesis [In Finnish]Google Scholar
  50. Oftedal OT, Boness DJ, Tedman RA (1987) The behavior, physiology, and anatomy of lactation in the pinnipedia. Current Mammalogy 1:175–245CrossRefGoogle Scholar
  51. Ryg M, Smith TG, Øritsland NA (1990) Seasonal changes in body mass and body composition of ringed seals (Phoca hispida) on Svalbard. Can J Zool 68:470–475CrossRefGoogle Scholar
  52. Ryg M, Øritsland NA (1991) Estimates of energy expenditure and energy consumption of ringed seals (Phoca hispida) throughout the year. Polar Res 10:595–602CrossRefGoogle Scholar
  53. Sinisalo T (2007) Diet and foraging of ringed seals in relation to Helminth parasite assemblages. PhD thesis, University of Jyväskylä, FinlandGoogle Scholar
  54. Sinisalo T, Jones RI, Helle E, Valtonen ET (2008) Changes in diets of individual Baltic ringed seals (Phoca hispida botnica) during their breeding season inferred from stable isotope analysis of multiple tissues. Mar Mamm Sci 24:159–170CrossRefGoogle Scholar
  55. Sinisalo T, Valtonen ET, Helle E, Jones RI (2006) Combining stable isotope and intestinal parasite information to evaluate dietary differences between individual ringed seals (Phoca hispida botnica). Can J Zool 84:823–831CrossRefGoogle Scholar
  56. Smith TG (1987) The ringed seal, Phoca hispida, of the Canadian western Arctic. Can Bull Fish Aquat Sci 216:1–81Google Scholar
  57. Smith TG, Hammill MO, Taugbøl G (1991) A review of the developmental, behavioural and physiological adaptations of the ringed seal, Phoca hispida, to life in the arctic winter. Arctic 44:124–131Google Scholar
  58. Smith TG, Stirling I (1975) The breeding habitat of the ringed seal (Phoca hispida) birth lairs in the Amundsen Gulf, Northwest Territories. Can J Zool 53:1297–1305CrossRefGoogle Scholar
  59. Sundqvist L, Harkonen T, Svensson CJ, Harding KC (2012) Linking climate trends to population dynamics in the Baltic ringed seal: impacts of historical and future winter temperatures. Ambio 41:865–871CrossRefGoogle Scholar
  60. Suuronen P, Lehtonen E (2012) The role of salmonids in the diet of grey and ringed seals in the Bothnian Bay, northern Baltic Sea. Fish Res 125–126:283–288CrossRefGoogle Scholar

Copyright information

© Mammal Research Institute, Polish Academy of Sciences, Białowieża, Poland 2018

Authors and Affiliations

  1. 1.Natural Resources Institute Finland (Luke)TurkuFinland
  2. 2.Department of Aquatic Resources, Institute of Marine ResearchSwedish University of Agricultural SciencesLysekilSweden
  3. 3.Finnish Food Safety Authority Evira, Veterinary Bacteriology and Pathology Research UnitWild and Aquatic Animal Pathology SectionOuluFinland

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