Mammalian Biology

, Volume 75, Issue 5, pp 427–436 | Cite as

Growth and age at sexual maturity of South American sea lions

  • M. Florencia GrandiEmail author
  • Silvana L. Dans
  • Néstor A. García
  • Enrique A. Crespo
Original Investigation


The average age at sexual maturity (ASM) is an important parameter for evaluating the reproductive potential or status of a population. South American sea lions, Otaria flavescens in Patagonia (Argentina) were exploited and reduced to less than 10% of pre-exploitation numbers. At present, the population is recovering at a rate of 6%. In this paper, we studied growth and age at sexual maturity of South American sea lions in the south-western south Atlantic by examining 219 individuals (females and males) collected between 1989–2008. Individuals were aged by counting growth layer groups in tooth sections, standard body length was measured and male and female reproductive organs were examined macroscopically and histologically to establish individual sexual maturity. Maximum recorded length for males and females was 264 cm and 200 cm, respectively, and maximum ages 19 and 21 yrs. ASM defined as the age where 50% of females are mature, was estimated at 4.8±0.5 years old, corresponding to a mean SL of 147 cm, about 81% of their asymptotic length. First observed ovulation occurred during the 4th year, first birth may occur between 4 and 5 years old. Males physiologically mature between 4–6 years, but the size of the testes shows that all males became sexually mature by the age of 9 years when they reach a mean SL of 212 cm, about 86% of their asymptotic body length. The present information on ASM and growth of O. flavescens will improve the development of population dynamics models, to investigate the impact of recovering sea lions populations on its marine environment, as well as its trophic interactions with commercial fisheries.


Otaria flavescens Average age at sexual maturity Body growth Patagonia 


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  1. Andersen, M., Hjelset, A.M., Gjertz, I., Lydersen, C., Gulliksen, B., 1999. Growth, age at sexual maturity and condition in bearded seals (Erignathus barbatus) from Svalbard, Norway. Polar Biol. 21, 179–185.CrossRefGoogle Scholar
  2. Bartheld, J.L., Pavés, H., Contreras, F., Vera, C., Manque, C., Miranda, D., Sepúlveda, D., Artacho, P., Ossman, L., 2006. Informe Final Proyecto FIP 2006-50. Cuantificación poblacional de lobos marinos en el litoral de la I a IV Región, Chile. 124 pp.Google Scholar
  3. Bester, M.N., 1995. Reproduction in the female subantarctic fur seal, Arctocephalus tropicalis. Mar. Mamm. Sci. 11, 362–375.CrossRefGoogle Scholar
  4. Boyd, I.L., Roberts, J.P., 1993. Tooth growth in male Antarctic fur seals (Arctocephalus gazella) from South Georgia: an indicator of long-term growth history. J. Zool. London 229, 177–190.CrossRefGoogle Scholar
  5. Boyd, I.L., Croxall, J.P., Lunn, N.J., Reid, K., 1995. Population demography of Antarctic fur seals: the costs of reproduction and implications for life-histories. J. Anim. Ecol. 64, 505–518.CrossRefGoogle Scholar
  6. Burnham, K.P., Anderson, D.R., 2004. Multimodel inference: understanding AIC and BIC in model selection. Soc. Meth. Res. 33, 261–304.CrossRefGoogle Scholar
  7. Butterworth, D.S., Punt, A.E., Oosthuizen, W.H., Wickens, P.A., 1995. The effect of future consumption by the Cape fur seal on catches and catch rates of the Cape hakes. 3: Modelling the dynamics of the Cape fur seal Arctocephalus pusillus pusillus. S. Afr. J. Mar. Sci. 16, 161–183.CrossRefGoogle Scholar
  8. Campagna, C., 1985. The breeding cycle of the southern sea lion, (Otaria byronia). Mar. Mamm. Sci. 1 (3), 210–218.CrossRefGoogle Scholar
  9. Campagna, C., Le Boeuf, B.J., 1988. Reproductive behaviour of southern sea lions. Behaviour 104, 233–261.CrossRefGoogle Scholar
  10. Campagna, C., Le Boeuf, B.J., Cappozzo, H.L., 1988a. Group raids: a mating strategy of male southern sea lions. Behaviour 105, 224–249.CrossRefGoogle Scholar
  11. Campagna, C., Le Boeuf, B.J., Cappozzo, H.L., 1988b. Pup abduction and infanticide in southern sea lions. Behaviour 107, 44–60.CrossRefGoogle Scholar
  12. Cassini, M.H., 1999. The evolution of reproductive systems in pinnipeds. Behav. Ecol. 10 (5), 612–616.CrossRefGoogle Scholar
  13. Committee on Marine Mammals, 1967. Standard measurements of seals. J. Mammal. 48, 459–462.CrossRefGoogle Scholar
  14. Crespo, E.A., 1988. Dinámica poblacional del lobo marino del sur Otaria flavescens (Shaw, 1800), en el norte del litoral patagónico. PhD thesis, Universidad de Buenos Aires, Buenos Aires, Argentina.Google Scholar
  15. Crespo, E.A., Pedraza, S.N., 1991. Estado actual y tendencia de la población de lobos marinos de un pelo (Otaria flavescens) en el litoral norpatagónico. Ecol. Aust. 1, 87–95.Google Scholar
  16. Crespo, E.A., Corcuera, J.F., López Cazorla, A., 1994. Interactions between marine mammals and fisheries in some coastal fishing areas of Argentina. In: Perrin, W.F., Donovan, G.P., Barlow, J. (Eds.), Guilnets and Cetaceans. Rep. Int. Whal. Commn. (Special Issue 15), pp. 269–281.Google Scholar
  17. Dabin, W., Beauplet, G., Crespo, E.A., Guinet, C., 2004. Age structure, growth and demographic parameters in breeding-age female subantarctic fur seals, Arctocephalus tropicalis. Can. J. Zool. 82, 1043–1050.CrossRefGoogle Scholar
  18. Dans, S.L., Crespo, E.A., Pedraza, S.N., Koen Alonso, M., 2004. Recovery of South American Sea Lion population in Northern Patagonia. Can. J. Fish. Aquat. Sci. 61, 1681–1690.CrossRefGoogle Scholar
  19. DeMaster, D.P., 1978. Calculation of the average age of sexual maturity in marine mammals. J. Fish. Res. Board. Can. 35, 912–915.CrossRefGoogle Scholar
  20. DeMaster, D.P., 1981. Estimating the average age of first birth in marine mammals. Can. J. Fish. Aquat. Sci. 38, 237–239.CrossRefGoogle Scholar
  21. DeMaster, D.P., 1984. Review of the techniques used to estimate the average age at attainment of sexual maturity in marine mammals. In: Perrin, W.F., Brownell Jr. R.L., DeMaster, D.P. (Eds.), Reproduction in Whales, Dolphins and Porpoises. Rep. Int. Whal. Comm. (Special Issue 6), pp.175–179.Google Scholar
  22. Dickie, G.S., Dawson, S.M., 2003. Age, growth, and reproduction in New Zealand fur seals. Mar. Mamm. Sci. 19, 173–185.CrossRefGoogle Scholar
  23. DINARA, Dirección Nacional de Recursos Acuáticos, 2006. Available via DIALOG. <>.
  24. Eberhardt, L.L., Siniff, D.B., 1977. Population dynamics and marine mammal management policies. J. Fish. Res. Board Can. 34, 183–190.CrossRefGoogle Scholar
  25. Frie, A.K., Potelov, V.A., Kingsley, M.C.S., Haug, T., 2003. Trends in age-at-maturity and growth parameters of female Northeast Atlantic harp seals, Pagophilus groenlandicus (Erxleben, 1777). J. Mar. Sci. 60, 1018–1032.Google Scholar
  26. Grandi, M.F., Dans, S.L., Crespo, E.A., 2008. Social composition and spatial distribution of colonies in an expanding population of South American sea lions. J. Mammal. 89 (5), 1218–1228.CrossRefGoogle Scholar
  27. Guinet, C., Cherel, Y., Ridoux, V., Jouventin, P., 1996. Consumption of marine resources by seabirds and seals in Crozet and Kerguelen waters: changes in relation to consumer biomass 1962–85. Antarct. Sci. 8, 23–30.CrossRefGoogle Scholar
  28. Hamilton, J.E., 1934. The southern sea lion (Otaria byronia) (de Blainville). Disc. Rep. 8, 269–318.Google Scholar
  29. Hamilton, J.E., 1939. A second report on the southern sea lion (Otaria byronia) (de Blainville). Disc. Rep. 19, 121–164.Google Scholar
  30. Hammill, M.O., Kingsley, M.C.S., Beck, G.G., Smith, T.G., 1995. Growth and condition in the Northwest Atlantic harp seal. Can. J. Fish. Aquat. Sci. 52, 478–488.CrossRefGoogle Scholar
  31. Hårding, K.C., Härkänen, T., 1995. Estimating mean age at sexual maturity in the crabeater seal Lobodon carcinophagus. Can. J. Fish. Aquat. Sci. 52, 2347–2352.CrossRefGoogle Scholar
  32. Harting, A.L., Baker, J.D., Johanos, T.C., 2007. Reproductive patterns of the Hawaiian monk seal. Mar. Mamm. Sci. 23 (3), 553–573.CrossRefGoogle Scholar
  33. Hohn, A.A., Chivers, S.J., Barlow, J., 1985. Reproductive maturity and seasonality of male spotted dolphins, Stenella attenuata, in the Eastern Tropical Pacific. Mar. Mamm. Sci. 1 (4), 273–293.CrossRefGoogle Scholar
  34. Koen Alonso, M., Crespo, E.A., Pedraza, S.N., García, N.A., Coscarella, M.A., 2000. Food habits of the South American sea lion Otaria flavescens, off Patagonia, Argentina. Fish. Bull. 98, 250–263.Google Scholar
  35. Koen-Alonso, M., Yodzis, P., 2005. Multispecies modelling of some components of the marine community of northern and central Patagonia, Argentina. Can. J. Fish. Aquat. Sci. 62, 1490–1512.CrossRefGoogle Scholar
  36. Laws, R.M., 1956. Growth and sexual maturity in aquatic mammals. Nature (London) 178, 193–194.CrossRefGoogle Scholar
  37. Laws, R.M., 1962. Age determination of pinniped with special reference to the growth layers in the teeth. Mamm. Biol. 27, 129–146.Google Scholar
  38. Laws, R.M., Sinha, A.A., 1993. Reproduction. In: Laws, R.M. (Ed.), Antarctic Seals: Research Methods and Techniques. Cambridge University Press, Cambridge UK, pp. 228–267.CrossRefGoogle Scholar
  39. Leberg, P.L., Brisbin, I.L., Smith, M.H., White, G.C., 1989. Factors affecting the analysis of growth patterns of large mammals. J. Mammal. 70, 275–283.CrossRefGoogle Scholar
  40. Lima, M., Páez, E., 1997. Demography and population dynamics of South American fur seals. J. Mammal. 78, 914–920.CrossRefGoogle Scholar
  41. Lunn, N.J., Boyd, I.L., Croxal, J.P., 1994. Reproductive performance of female Antarctic fur seals: the influence of age, breeding experience, environmental variation and individual quality. J. Anim. Ecol. 63, 827–840.CrossRefGoogle Scholar
  42. McLaren, I.A., Smith, T.G., 1985. Population ecology of seals: retrospective and prospective views. Mar. Mamm. Sci. 1, 54–83.CrossRefGoogle Scholar
  43. Murie, J., 1872. Researches upon the anatomy of Pinnipedia. Part II: Descriptive anatomy of the sea lion (Otaria jubata). Trans. Zool. Soc. London 7 (8), 527–596.CrossRefGoogle Scholar
  44. Páez, E., 2006. Situación de la administratión del recurso lobos y leones marinos en Uruguay. In: Menafra, R., Rodríguez-Gallego, L., Scarabino, F., Conde, D. (Eds.), Bases para la conservatión y el manejo de la costa uruguaya. Vida Silvestre, Sociedad Uruguaya para la Conservación de la Naturaleza, Montevideo, pp. 577–583.Google Scholar
  45. Pascual, M.A., Adkison, M.D., 1994. The decline of the Steller sea lion in the northeast Pacific: demography, harvest or environment?. Ecol. Appl. 4, 393–403.CrossRefGoogle Scholar
  46. Perrin, W.F., Donovan, G.P., 1984. Report of the workshop. In: Perrin, W.F., Brownell Jr., R.L., DeMaster, D.P. (Eds.), Reproduction in Whales, Dolphins and Porpoises. Rep. Int. Whal. Commn. (Special Issue 6), pp. 1–24.Google Scholar
  47. Pistorius, P.A., Bester, M.N., Kirkman, S.P., Taylor, F.E., 2001. Temporal changes in fecundity and age of sexual maturity of southern elephant seals at Marion Island. Polar Biol. 24, 343–348.CrossRefGoogle Scholar
  48. Pitcher, K.W., Calkins, D.G., 1981. Reproductive biology of Steller sea lions in the Gulf of Alaska. J. Mammal. 62, 599–605.CrossRefGoogle Scholar
  49. R Development Core Team, 2008. R: A Language and Environment for Statistical Computing. ISBN:3-900051-07-0, Available via DIALOG. <>.
  50. Reijnders, P., Brasseur, S., van der Toorn, J., van der Wolf, P., Boyd, I., Harwood, J., Lavigne, D., Lowry, L., 1993. Seals, fur seals, sea lions and walrus: status survey and conservation action plan. IUCN/SSC Seal Specialist Group. World Conservation Union, Gland, Switzerland.Google Scholar
  51. Reiter, J., Panken, K.J., Le Boeuf, B.J., 1981. Female competition and reproductive success in northern elephant seals. Anim. Behav. 29, 670–687.CrossRefGoogle Scholar
  52. Reyes, L., Crespo, E., Szapkievich, V., 1999. Distribution and population size of the southern sea lion (Otaria flavescens) central and southern Chubut, Patagonia, Argentina. Mar. Mamm. Sci. 15, 478–493.CrossRefGoogle Scholar
  53. Riedman, M., 1990. The Pinnipeds; Seals, Sea Lions, and Walruses. University of California Press, Berkley.Google Scholar
  54. Rosas, F.C.W., Haimovici, M., Pinedo, A.M., 1993. Age and growth of the South American sea lion, Otaria flavescens (Shaw, 1800), in southern Brazil. J. Mammal. 74 (1), 141–147.CrossRefGoogle Scholar
  55. Rosas, F.C.W., Pinedo, M.C., Marmontel, M., Haimovici, M., 1994. Seasonal movements of the South American sea lion (Otaria flavescens, Shaw) off the Rio Grande do Sul coast, Brazil. Mammalia 58, 51–59.CrossRefGoogle Scholar
  56. Schiavini, A.C.M., Crespo, E.A., Szapkievich, V.B., 2004. Status of the population of South American sea lion (Otaria flavescens Shaw, 1800) in southern Argentina. Mamm. Biol. 69, 1–11.CrossRefGoogle Scholar
  57. Sepúlveda, M., Oliva, D., Sielfeld, W., Perez, M.J., Moraga, R., Schrader, D., Urra, A., Díaz, H., 2006. Informe Final Proyecto FIP 2006-49. Cuantificación poblacional de lobos marinos en el litoral de la V a IX Región, Chile, 100 pp.Google Scholar
  58. Smith, T.G., 1973. Population dynamics of the Ringed Seal in the Canadian Eastern Arctic. Bull. Fish. Res. Board Can. 181, 1–52.Google Scholar
  59. Soto, K.H., Trites, A.W., Arias-Schreiber, M., 2004. The effects of prey availability on pup mortality and the timing of birth of South American sea lions (Otaria flavescens) in Peru. J. Zool. London 264, 419–428.CrossRefGoogle Scholar
  60. Thompson, D., Strange, I., Riddy, M., Duck, C.D., 2005. The size and status of the population of southern sea lions Otaria flavescens in the Falkland Islands. Biol. Conserv. 121, 357–367.CrossRefGoogle Scholar
  61. Towell, R.G., Ream, R.R., York, A.E., 2006. Decline in northern fur seal (Callorhinus ursinus) pup production on the Pribilof Islands. Mar. Mamm. Sci. 22, 486–491.CrossRefGoogle Scholar
  62. Trites, A.W., 1991. Fetal growth of northern fur seals: life history strategy and sources of variation. Can. J. Zool. 69, 2608–2617.CrossRefGoogle Scholar
  63. Trites, A.W., Donnelly, C.P., 2003. The decline of Steller sea lions Eumetopias jubatus in Alaska: a review of the nutritional stress hypothesis. Mammal Rev. 33, 3–28.CrossRefGoogle Scholar
  64. Túnez, J.I., Centrón, D., Cappozzo, H.L., Cassini, M.H., 2007. Geographic distribution and diversity of mitochondrial DNA haplotypes in South American sea lions (Otaria flavescens) and fur seals (Arctocephalus australis). Mamm. Biol. 72 (4), 193–203.CrossRefGoogle Scholar
  65. Vaz-Ferreira, R., 1982. Otaria flavescens (Shaw), South American sea lion. In: Mammals of the Seas: Small Cetaceans, Seals, Sirenians and Otters. Food Agr. Org. Fish. Ser. 4(5), pp. 477–495.Google Scholar
  66. Venegas, C., 2001. Informe Final Proyecto FIP 2000-22. CuantificaciOn poblacional de lobos marinos en la XII Región, Chile, 92 pp.Google Scholar
  67. Videla, P.H.B., 1980. Recursos Naturales de la Tierra del Fuego: Lobos Marinos. Directión de Intereses Marinos, Ushuaia.Google Scholar
  68. Wickens, P.A., 1993. Life expectancy of fur seals, with special reference to the South African (Cape) fur seal. S. Afr. J. Wildl. Res. 23, 101–106.Google Scholar
  69. Wickens, P.A., York, A.E., 1997. Comparative population dynamics of fur seals. Mar. Mamm. Sci. 13, 241–292.CrossRefGoogle Scholar
  70. Winship, A.J., Trites, A.W., Calkins, D.G., 2001. Growth in body size of the Steller sea lion (Eumetopias jubatus). J. Mammal. 82 (2), 500–519.CrossRefGoogle Scholar
  71. York, A.E., 1983. Average age at first reproduction of the northern fur seal (Callorhinus ursinus). Can. J. Fish. Aquat. Sci. 40, 121–127.CrossRefGoogle Scholar
  72. York, A.E., 1987. On comparing the population dynamics of fur seals. In: Croxall J.P., Gentry R.L. (Eds.), Status, Biology, and Ecology of Fur Seals. NOAA Technical Report NMFS 51, pp. 133–140.Google Scholar
  73. York, A.E., Hartley, J.R., 1981. Pup production following harvest of females northern fur seals. Can. J. Fish. Aquat. Sci. 38, 84–90.CrossRefGoogle Scholar

Copyright information

© Deutsche Gesellschaft für Säugetierkunde 2009

Authors and Affiliations

  • M. Florencia Grandi
    • 1
    Email author
  • Silvana L. Dans
    • 1
    • 2
  • Néstor A. García
    • 1
  • Enrique A. Crespo
    • 1
    • 2
  1. 1.Laboratory of Marine MammalsCENPAT-CONICETChubutArgentina
  2. 2.National University of Patagonia San Juan BoscoChubutArgentina

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