Population albatross

Páginas: 23 (5723 palabras) Publicado: 23 de diciembre de 2010
Preprint, 2008
doi: 10.3354/esr00089


Published online May 28, 2008

Contribution to the Theme Section ‘Fisheries bycatch: problems and solutions’


Population status of the Critically Endangered waved albatross Phoebastria irrorata, 1999 to 2007
David J. Anderson1,*, Kathryn P. Huyvaert2, Jill A. Awkerman1, 3, Carolina B.Proaño4, W. Bryan Milstead5, Gustavo Jiménez-Uzcátegui5, Sebastian Cruz4, Jacquelyn K. Grace1
2 1 Dept. of Biology, Wake Forest University, Winston-Salem, North Carolina 27109-7325, USA Dept. of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, Colorado 80523-1474, USA 3 National Health and Environmental Effects Research Laboratory, Environmental Protection Agency,Gulf Ecology Division, Gulf Breeze, Florida 32561-5239, USA 4 Colegio de Ciencias de la Vida, Universidad San Francisco de Quito, Quito, Ecuador 5 Charles Darwin Research Station, Isla Santa Cruz, Galápagos, Ecuador

ABSTRACT: Understanding the demography of the Critically Endangered waved albatross Phoebastria irrorata is crucial for effective policy responses to recent threats, most notablyfishery mortality. Using current vital rates data and a stochastic matrix model, we confirm the conclusion of Awkerman et al. (2006) that the population growth rate (λ) was less than 1 in recent years, indicating a shrinking population. Earlier comparisons of recent population size suggested that the breeding population shrunk between 1994 and 2001, but these were based on only 2 counts. A new countin 2007 indicated continued reduction in breeding population size, and the magnitude of the recent reduction was consistent with that projected by our model. New information suggests that plastic ingestion appears to pose a minor threat, if any, to this species, in contrast to the serious problems that it causes in some other albatrosses. Reduction of adult mortality in the coastal fisheryappears to be the most effective means to stabilize this threatened species. KEY WORDS: Annual adult survival · Fecundity · Galápagos · Stochastic matrix model · Plastic pollution · Waved albatross
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INTRODUCTION The waved albatross Phoebastria irrorata was recently uplisted to Critically Endangered on the InternationalUnion for Conservation of Nature (IUCN) Red List (IUCN 2008), based in part on strong evidence of reduced annual adult survival and fishery mortality at the species’ principal feeding area off the western coast of South America (Awkerman et al. 2006). Weaker evidence concerning trend in population size is consistent with a recent decline (Anderson et al. 2002, Awkerman et al. 2006), but the data arescant, based on only 3 estimates (1970 to 1971, 1994, and 2001). The scarcity of population size estimates motivated an effort in May 2007 to provide a fourth point to inform new policy processes (cf. under the Agreement on the Conservation of
*Email: da@wfu.edu

Albatrosses and Petrels) resulting from the ‘uplisting’. Here we report the results of this fourth population size estimate. We alsoupdate the results of Awkerman et al. (2006), presenting new results concerning annual adult survival over the period 1999 to 2006 and incorporating improved vital rate estimates into population matrix models. Finally, we report the first information concerning plastic ingestion in this species. Plastic ingestion has been implicated in nestling mortality of some other albatross species (Sileo etal. 1990) and has never been evaluated as a risk for waved albatrosses. Essentially a single-island endemic, almost all waved albatrosses nest on Isla Española (aka Hood Island), Galápagos Islands, Ecuador (1° 20’ S, 89° 40’ W), simplifying the task of estimating population size to some extent. However, the terrain is presently heavily vege© Inter-Research 2008 · www.int-res.com


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