Rolland V, Nevoux M, Barbraud C, Weimerskirch H
Centre d'Etudes Biologiques de Chizé, Centre National de la Recherche Scientifique, 79360 Villiers en Bois, France.
Ecol Appl. 2009 Jul;19(5):1336-46. doi: 10.1890/08-1060.1.
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 would increase at 3.5% per year, suggesting that bycatch mortality probably currently limits the Black-browed Albatross population at Kerguelen. Our study shows how this type of model could be useful to predict trajectories of top predator populations, and eventually lower trophic web levels, in relation to climatic projections and future human activities. We highlight the need to reinforce mitigation measures.
气候以及渔业等人类活动会影响许多动物物种。然而，人们对种群生命率受影响的人口统计学过程及其增长率的敏感性了解甚少。黑眉信天翁（Thalassarche melanophrys）是一种寿命较长的受威胁海鸟物种。先前的研究表明，在凯尔盖朗群岛繁殖的种群，其成年个体的存活率和繁殖成功率在繁殖季和非繁殖季均受到海表温度异常（SSTA）的影响，并且在塔斯马尼亚海域因金枪鱼延绳钓的兼捕死亡率而受到影响。在此，我们利用在凯尔盖朗群岛监测了26年的一个黑眉信天翁繁殖群体的长期人口统计学数据，估算了从生命周期的早期到成年阶段的所有人口统计学参数，以便构建一个完全参数化的种群模型，并预测在几种气候和捕捞努力情景下的种群增长率。观测到的种群增长率（1.003）表明该种群稳定或略有增长，我们的种群模型给出了相近的估计值1.008。种群增长率对有经验繁殖者的存活率更为敏感，相应地对孵化期间海表温度异常的变化以及金枪鱼延绳钓努力（两者均影响有经验繁殖者的存活率）更为敏感，而对其他人口统计学参数/环境协变量则不然。种群的稳定源于人口统计学参数与环境条件之间的多种因素和复杂关系，因此种群平衡很不稳定。如果捕捞努力维持在当前水平且正海表温度异常增加，或者相反，如果捕捞努力减少且海表温度异常保持与当前值相似，那么种群将会增加。然而，如果越冬地的捕捞努力增加20%（即达到4000万个鱼钩），而海表温度异常没有任何变化，那么种群将以每年0.9%的速度减少。如果停止捕捞努力，种群将以每年3.5%的速度增加，这表明兼捕死亡率目前可能限制了凯尔盖朗群岛的黑眉信天翁种群数量。我们的研究表明，这种类型的模型对于预测顶级捕食者种群的动态轨迹以及最终较低营养级的食物网水平与气候预测和未来人类活动的关系可能是有用的。我们强调加强缓解措施的必要性。
