School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand.
Ecol Appl. 2013 Oct;23(7):1677-90. doi: 10.1890/12-1657.1.
Superpopulation capture-recapture models are useful for estimating the abundance of long-lived, migratory species because they are able to account for the fluid nature of annual residency at migratory destinations. Here we extend the superpopulation POPAN model to explicitly account for heterogeneity in capture probability linked to reproductive cycles (POPAN-tau). This extension has potential application to a range of species that have temporally variable life stages (e.g., non-annual breeders such as albatrosses and baleen whales) and results in a significant reduction in bias over the standard POPAN model. We demonstrate the utility of this model in simultaneously estimating abundance and annual population growth rate (lamda) in the New Zealand (NZ) southern right whale (Eubalaena australis) from 1995 to 2009. DNA profiles were constructed for the individual identification of more than 700 whales, sampled during two sets of winter expeditions in 1995-1998 and 2006-2009. Due to differences in recapture rates between sexes, only sex-specific models were considered. The POPAN-tau models, which explicitly account for a decrease in capture probability in non-calving years, fit the female data set significantly better than do standard superpopulation models (deltaAIC > 25). The best POPAN-tau model (AIC) gave a super-population estimate of 1162 females for 1995-2009 (95% CL 921, 1467) and an estimated annual increase of 5% (95% CL--2%, 13%). The best model (AIC) gave a superpopulation estimate of 1007 males (95% CL 794, 1276) and an estimated annual increase of 7% (95% CL 5%, 9%) for 1995-2009. Combined, the total superpopulation estimate for 1995-2009 was 2169 whales (95% CL 1836, 2563). Simulations suggest that failure to account for the effect of reproductive status on the capture probability would result in a substantial positive bias (+19%) in female abundance estimates.
超总体捕获-再捕获模型对于估计长寿、迁徙物种的数量非常有用，因为它们能够解释迁徙目的地年度居留的流动性。在这里，我们将超总体 POPAN 模型扩展到明确考虑与繁殖周期相关的捕获概率的异质性（POPAN-tau）。这种扩展可能适用于具有时间可变生命阶段的一系列物种（例如，信天翁和须鲸等非年度繁殖者），并导致与标准 POPAN 模型相比，偏差显著减少。我们在 1995 年至 2009 年期间，通过同时估计新西兰南部露脊鲸（Eubalaena australis）的数量和年度种群增长率（lambda），证明了该模型的实用性。对在 1995 年至 1998 年和 2006 年至 2009 年两次冬季考察期间采样的 700 多头鲸鱼进行了 DNA 谱构建，以进行个体识别。由于性别间的再捕获率存在差异，因此仅考虑了特定性别的模型。明确考虑到非产犊年份捕获概率降低的 POPAN-tau 模型，与标准超总体模型相比，显著更好地拟合雌性数据集（deltaAIC > 25）。最佳 POPAN-tau 模型（AIC）给出了 1995 年至 2009 年期间 1162 头雌性的超总体估计值（95%置信区间为 921、1467）和估计的年增长率为 5%（95%置信区间为--2%、13%）。最佳模型（AIC）给出了 1995 年至 2009 年期间 1007 头雄性的超总体估计值（95%置信区间为 794、1276）和估计的年增长率为 7%（95%置信区间为 5%、9%）。1995 年至 2009 年期间，总超总体估计值为 2169 头鲸鱼（95%置信区间为 1836、2563）。模拟表明，如果不考虑繁殖状况对捕获概率的影响，雌性数量估计值将出现实质性正偏差（+19%）。
