Respective impact of climate and fisheries on the growth of an albatross population

• Published in: Ecological Applications
• Main Authors: Rolland, V., Nevoux, Marie, Barbraud, Christophe, Weimerskirch, Henri
• Other Authors: Centre d'études biologiques de Chizé (CEBC), Centre National de la Recherche Scientifique (CNRS), Institut Paul Emile Victor IPEV 109, Terres Australes et Antarctiques Francaises; ANR Biodiversity
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2008
• Subjects: Southern Ocean; Kerguelen; climate; Black-browed Albatross; bycatch; longline fisheries; population dynamics; population projections; sea surface temperature anomalies; Southern Oscillation Index; Thalassarche melanophrys; envir; demo
• Online Access: https://doi.org/10.1890/08-1060.1; https://hal.archives-ouvertes.fr/hal-00396591

International audience Climate and human activities such as fisheries impact many animal species. However, the demographic processes through which the population vital rates are affected, and the sensitivity of their growth rates, are poorly understood. The Black-browed Albatross, Thalassarche melanophrys, is a long-lived threatened seabird species. Previous studies have shown that the adult survival and breeding success of the population breeding at Kerguelen are affected by sea surface temperature anomalies (SSTA) during both the breeding and the nonbreeding season, and by tuna long-lining in Tasmanian waters through bycatch mortality. Here, using long-term demographic data from a Black-browed Albatross colony monitored for 26 years at Kerguelen, we estimate all demographic parameters from early to adult stages of the life cycle in order to build a fully parameterized population model and predict population growth rates under several scenarios of climate and fishing effort. The observed population growth rate (1.003) indicates that the population was stable or slightly increasing, and our population model gives a close estimate of 1.008. Population growth rate is more sensitive to survival of experienced breeders and accordingly to a change in SSTA during incubation and to tuna long-lining effort (both affecting survival of experienced breeders) than to other demographic parameters/environmental covariates. The population stability results from multiple factors and complex relationships between demographic parameters and environmental conditions, and therefore population equilibrium is precarious. If fishing effort remains stable at its current level and positive SSTA increase, or inversely if fishing effort decreases and SSTA remain similar to present values, then the population would increase. However, if fishing effort increases by 20% (i.e., to 40 million hooks) on the wintering grounds, without any change in SSTA, then the population would decrease at 0.9% per year. If fishing effort stops, the population ...