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Effective population size for South American sea lions along the Peruvian coast: the survivors of the strongest El Niño event in history

Published online by Cambridge University Press:  04 September 2012

Larissa Rosa de Oliveira ,
Lúcia Darsie Fraga  and
Patricia Majluf
Larissa Rosa de Oliveira*
Affiliation:
Laboratório de Ecologia de Mamíferos, Universidade do Vale do Rio dos Sinos (UNISINOS), Avenida Unisinos, 950, São Leopoldo, RS, Brasil, 93022-000 Grupo de Estudos de Mamíferos Aquáticos do Rio Grande Sul (GEMARS), Avenida Tramandaí, 976, Tramandaí, RS, 95625-000, Brazil Centro para la Sostenibilidad Ambiental, Universidad Peruana Cayetano Heredia (UPCH), Armendáriz 445, Miraflores, Lima 18, Peru
Lúcia Darsie Fraga
Affiliation:
Laboratório de Ecologia de Mamíferos, Universidade do Vale do Rio dos Sinos (UNISINOS), Avenida Unisinos, 950, São Leopoldo, RS, Brasil, 93022-000
Patricia Majluf
Affiliation:
Centro para la Sostenibilidad Ambiental, Universidad Peruana Cayetano Heredia (UPCH), Armendáriz 445, Miraflores, Lima 18, Peru
*
Correspondence should be addressed to: L.R. de Oliveira, Laboratório de Ecologia de Mamíferos, Universidade do Vale do Rio dos Sinos (UNISINOS), Avenida Unisinos, 950, São Leopoldo, RS, Brasil, 93022-000 email: lari.minuano@gmail.com
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Abstract

The South American sea lion, Otaria flavescens, has been considered vulnerable and under the threat of extinction in Peru due to the drastic demographic changes as a result of the impact of low food availability and the unusual timing of the severe El Niño event of 1997–1998. We present the first estimate of effective population size (Ne) for the species that takes into account the effects of mating system and variation in population size in different generations caused by the severe El Niño event of 1997–1998. The resulting Ne was 7715 specimens. We believe that the estimated Ne for the Peruvian population is not a critical value, because it is higher than the mean minimum viable population generally accepted for vertebrates (ca. 5000 breeding adults). However, the viability of O. flavescens on the Peruvian coast may depend primarily on local availability of food resources. Climatic change models predict stronger and more frequent El Niño events. In this sense, the Ne of 7715 should be considered as a value to be maintained in order to keep the population large enough to avoid inbreeding or to retain adaptive genetic variation to survive to future El Niño events. Moreover, this Ne estimate is important data in discussions about resuming culling activities, based on the statement of an increasing competition between fishery activity and sea lions during El Niño events. Thus, this Ne should be taken into account in future management plans to ensure the conservation of the species on the Peruvian coast.

Keywords

effective population sizeOtaria flavescensPeruvian populationEl Niño Southern Oscillation
Type
Research Article
Information
Journal of the Marine Biological Association of the United Kingdom , Volume 92 , Issue 8: Marine Mammals , December 2012 , pp. 1835 - 1841
Copyright
Copyright © Marine Biological Association of the United Kingdom 2012

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References

REFERENCES

Aguayo, A. and Maturana, R. (1973) Presencia del lobo marino común Otaria flavescens en el litoral chileno. Biología Pesquera 6, 49–75.Google Scholar
Arias-Schereiber, M. (2000) Distribuición, tamaño y estructura de las poblaciones de lobos marinos Arctocephalus australis y Otaria byronia en el litoral Peruano durante 1999. Informe Anual 1999. Instituto del Mar del Perú. Informe Interno. Instituto Del Mar Del Perú (IMARPE), Esq. Gamarra y Gral. Valle s/n, Chucuito, Callao, Peru.Google Scholar
Arias-Schreiber, M. (2003) Prey spectrum and feeding behavior of two sympatric pinnipeds (Arctocephalus australis and Otaria flavescens) in relation to the 1997–98 ENSO in southern Peru. Master's thesis. University of Bremen, Germany.Google Scholar
Arias-Schreiber, M. and Rivas, C. (1998) Distribución, tamaño y estructura de las poblaciones de lobos marinos Arctocephalus australis y Otaria byronia en el litoral Peruano, en Noviembre 1996 y Marzo 1997. Informe Progresivo del Instituto del Mar del Perú 73, 17–32.Google Scholar
Caballero, A. (1994) Developments in the prediction of effective population size. Heredity 73, 657–679.CrossRefGoogle ScholarPubMed
Campagna, C., Le Boeuf, B.J. and Cappozzo, H.L. (1988) Group raids: a mating strategy of male Southern sea lions. Behaviour 105, 224–249.Google Scholar
Cane, M.A. (1983) Oceanographic events during El Niño. Science 222, 1189–1195.CrossRefGoogle ScholarPubMed
Capozzo, L.H. and Perrin, W.F. (2008) South American sea lion, Otaria flavescens. In Perrin, W.F., Würsig, B. and Thewissen, J.G.M. (eds) Encyclopedia of marine mammals. Amsterdam: Academic Press, pp. 1076–1079.Google Scholar
Crespo, E.A., Nepomnaschy, P., Alonso, M.K. and García, N. (1990) Análisis preliminares de la dieta de mamíferos marinos sobre la base de contenidos estomacales y heces. In Oporto, J.A. (ed.) Reunión de Trabajo Expertos en Mamíferos Acuáticos de la América del Sur, 4. Anales de 4 Reunión de Trabajo Expertos en Mamíferos Acuáticos de la América del Sur. Valdivia: Imprenta Universitaria SA, Universidad Austral de Chile, pp. 75–88.Google Scholar
Crespo, E.A., Oliva, D., Dans, S.L. and Sepúlveda, M. (2009) Estado de situación del lobo marino común Otaria flavescens en su área de distribución (Informe del Taller de Trabajo). Valparaíso, 50 pp.Google Scholar
Crow, J.F. and Kimura, M. (1970) An introduction to population genetics theory. New York: Harper and Row.Google Scholar
Cushing, D.H. (1982) Climate and fisheries. London: Academic Press.Google Scholar
Dans, S., Alonso, M., Crespo, E., Pedraza, S. and García, N. (2003) Interactions between marine mammals and high seas fisheries in Patagonia: an integrated approach. In Gales, I., Nicholas, J. and Hindell, M.A. (eds) Marine mammals: fisheries, tourism and management issues. Collingwood, Victoria: CSIRO Publishing, pp. 100–115.Google Scholar
Frankham, R. (1995) Effective population size/adult population size ratios in wildlife: a review. Genetics Research 66, 95–107.CrossRefGoogle Scholar
Frankham, R., Balou, J.D. and Briscoe, D.A. (2002) Introduction to conservation genetics. Cambridge: Cambridge University Press.CrossRefGoogle Scholar
George-Nascimiento, M., Bustamante, R. and Oyarzún, C. (1985) Feeding ecology of the South American sea lion Otaria flavescens: food contents and food selectivity. Marine Ecology Progress Series 21, 135–143.CrossRefGoogle Scholar
Glantz, M.H. (1996) Currents of change—El Niño's impact on climate and society. 2nd edition. Cambridge: Cambridge University Press.Google Scholar
Grimwood, I.R. (1969) Notes on the distribution and status of some Peruvian mammals. American Commitee for International Wild Life Protection and New York Zoological Society, Special Publication 21, 1–86.Google Scholar
Hedrick, P.W. (2000) Genetics of populations. Sudbury, UK: Jones and Bartlet.Google Scholar
Husband, B.C. and Barrett, S.C.H. (1992) Effective population-size and genetic drift in tristylous Eichhornia paniculata (Pontederiaceae). Evolution 46, 1875–1890.CrossRefGoogle ScholarPubMed
Idyll, C.P. (1973) The anchovy crisis. Scientific American 228, 22–29.CrossRefGoogle Scholar
IMARPE (2006) Censo Nacional de Lobo Chusco (Otaria flavescens) (2006). UBI Depredadores Superiores. Informe Interno.Google Scholar
Jefferson, T.A., Webber, M.W. and Pitman, R.L. (2008) Marine mammals of the world: a comprehensive guide to their identification. Amsterdam: Academic Press.Google Scholar
Koen Alonso, M., Crespo, E.A., Pedraza, S.N., García, N.A. and Coscarella, M.A. (2000) Food habits of the South American sea lion Otaria flavescens, off Patagonia, Argentina. Fishery Bulletin 98, 250–263.Google Scholar
Lama, A. (2010) Aphrodisiac market fuels killing of sea lions (available at http://www.tierramerica.info/nota.php?lang=engandidnews=1715).Google Scholar
Majluf, P. and Trillmich, F. (1981) Distribution and abundance of sea lions (Otaria byronia) and fur seals (Arctocephalus australis) in Peru. Zeitschrift für Saugetierkunde 46, 384–393.Google Scholar
Majluf, P. (1992) Timing of births and juvenile mortality in the South American fur seal in Peru. Journal of Zoology 227, 367–383.CrossRefGoogle Scholar
Majluf, P., Babcock, E.A., Riveros, J.C., Schreiber, M.A. and Alderete, W. (2002) Catch and bycatch of sea birds and marine mammals in the small-scale fishery of Punta San Juan, Peru. Conservation Biology 16, 1333–1343.CrossRefGoogle Scholar
McPhaden, M.J. (1999) Genesis and evolution of the 1997–98 El Niño. Science 283, 950–954.CrossRefGoogle ScholarPubMed
NCDC–NOOA (2004) The top 10 El Niño events of the 20th century (available at http://www.ncdc.noaa.gov/oa/climate/research/1998/enso/10elnino.html).Google Scholar
Neigel, J.E. (1996) Estimation of effective population size and migration parameters from genetic data. In Smith, T.B. and Wayne, R.K. (eds) Molecular genetics approaches in conservation. Oxford: Oxford University Press, pp. 329–346.CrossRefGoogle Scholar
Nunney, L. (1995) Measuring the ratio of effective population size to adult numbers using genetic and ecological data. Evolution 49, 389–392.CrossRefGoogle ScholarPubMed
Nunney, L. (2002) The effective size of annual plant populations: the interaction of a seed bank with fluctuating population size in maintaining genetic variation. American Naturalist 160, 195–204.CrossRefGoogle ScholarPubMed
Nunney, L. and Elam, D.R. (1994) Estimating the effective population size of conserved populations. Conservation Biology 8, 175–184.CrossRefGoogle Scholar
Oliveira, L.R., Arias-Schreiber, M., Meyer, D. and Morgante, J.S. (2006) Effective population size in a bottlenecked fur seal population. Biological Conservation 131, 505–509.CrossRefGoogle Scholar
Oliveira, L.R., Ott, P.H. and Malabarba, L.R. (2008) Ecologia alimentar dos pinípedes do Sul do Brasil e uma avaliação de suas interações com atividades pesqueiras. In Reis, N.R., Peracci, A.L. and Santos, G.A.S.D. (eds) Ecologia de mamíferos. Londrina, Brazil: Technical Books, pp. 97–116.Google Scholar
Oliveira, L.R., Meyer, D., Hoffman, J.I., Majluf, P. and Morgante, J.S. (2009) Evidence of a genetic bottleneck in an El Niño affected population of South American fur seals, Arctocephalus australis. Journal of the Marine Biological Association of the United Kingdom 89, 1717–1725.CrossRefGoogle Scholar
Piazza, A. (1969) Los lobos marinos. Pesca y Caza (Perú) 9, 1–29.Google Scholar
Reed, D.H., Grady, J.J.O., Brook, B.W., Ballou, J.D. and Frankham, R. (2003) Estimates of minimum viable population sizes for vertebrates and factors influencing those estimates. Biological Conservation 113, 23–24.CrossRefGoogle Scholar
Riedman, M.L. (1990) The pinnipeds. Seals, sea lions and walruses. Berkeley, CA: University of California Press.CrossRefGoogle Scholar
Ryther, J.H. (1969) Photosynthesis and fish production in the sea. Science 166, 72–76.CrossRefGoogle ScholarPubMed
Seal Conservation Society (2010) South American sea lion (available at http://www.greenchannel.com/tec/species/samslion.html).Google Scholar
Sepúlveda, M. and Oliva, D. (2005) Interactions between South American sea lions Otaria flavescens (Shaw) and salmon farms in southern Chile. Aquaculture Research 36, 1062–1068.CrossRefGoogle Scholar
Soto, K.H. and Trites, A.W. (2004) The effects of prey availability on pup mortality and the timing of birth of South American sea lions (Otaria flavescens) in Peru. Journal of Zoology 264, 419–428.CrossRefGoogle Scholar
Soto, K.H., Trites, A.W. and Arias-Schreiber, M. (2006) Changes in diet and maternal attendance of South American sea lions indicate changes in the marine environment and prey abundance. Marine Ecology Progress Series 312, 277–290.CrossRefGoogle Scholar
Stevens, M.A. and Boness, D.J. (2003) Influences of habitat features and human disturbance on use of breeding sites by a declining population of Southern fur seals (Arctocephalus australis). Journal of Zoology 260, 145–152.CrossRefGoogle Scholar
Szteren, D. and Páez, E. (2002) Predation by southern sea lions (Otaria flavescens) on artisanal fishing catches in Uruguay. Marine and Freshwater Research 53, 1161–1167.CrossRefGoogle Scholar
Thomas, C.D. (1990) What do real population dynamics tell us about minimum viable population sizes? Conservation Biology 4, 324–327.CrossRefGoogle Scholar
Thompson, D., Strange, I., Riddy, M. and Duck, C.D. (2005) The size and status of the population of southern sea lions Otaria flavescens in the Falkland Islands. Biological Conservation 121, 357–367.CrossRefGoogle Scholar
Tovar, H. and Fuentes, H. (1984) Magnitud poblacional de lobos marinos en el litoral peruano en marzo de 1984. Informe Instituto del Mar del Perú 88, 32 pp.Google Scholar
Traill, L.W., Bradshaw, C.J.A. and Brook, B.W. (2007) Minimum viable population size: a meta-analysis of 30 years of published estimates. Biological Conservation 139, 159–166.CrossRefGoogle Scholar
Traill, L.W., Brook, B.W., Frankham, R.R. and Bradshaw, C.J.A. (2010) Pragmatic population viability targets in a rapidly changing world. Biological Conservation 143, 28–34.CrossRefGoogle Scholar
Túnez, J.I., Cappozzo, H.L. and Cassini, M.H. (2008) Natural and anthropogenic factors associated with the distribution of South American sea lion along the Atlantic coast. Hydrobiologia 598, 191–202.CrossRefGoogle Scholar
Vaz-Ferreira, R. (1965) Comportamiento antisocial en machos subadultos de Otaria byronia (de Blainville), (lobos marino de un pelo). Revista de la Facultad de Humanidades y Ciencias 22, 204–207.Google Scholar
Vaz-Ferreira, R. (1981) South American sea lion, Otaria flavescens (Shaw, 1800). In Ridgeway, S.H. and Harrison, R.J. (eds) Handbook of marine mammals. Volume 1. London: Academic Press, pp. 39–66.Google Scholar
Vaz-Ferreira, R. (1982) Arctocephalus australis Zimmerman, South American fur seal. In Mammals in the seas, small cetaceans, seals, sirenians and otters. Volume 4. Rome: FAO Fisheries series, pp. 497–508.Google Scholar
Vucetich, J.A., Waite, T.A. and Nunney, L. (1997) Fluctuating population size and the ratio of effective to census population size (Ne/N). Evolution 51, 2015–2019.CrossRefGoogle Scholar
Vucetich, J.A. and Waite, T.A. (1998) Number of censuses required for demographic estimation of effective population size. Conservation Biology 12, 1023–1030.CrossRefGoogle Scholar
Willi, Y., Van Buskirk, J., Schmid, B. and Fischer, M. (2007) Genetic isolation of fragmented populations is exacerbated by drift and selection. Journal of Evolutionary Biology 20, 534–542.CrossRefGoogle ScholarPubMed
Wright, S. (1931) Evolution in Mendelian populations. Genetics 16, 97–159.CrossRefGoogle ScholarPubMed