Mathematics and Statistics Department, University of Otago, P.O. Box 56, Dunedin, New Zealand.
Ecol Appl. 2011 Jun;21(4):1308-26. doi: 10.1890/09-0813.1.
The annual hunt of Muttonbirds (chicks of the Sooty Shearwater, Puffinus griseus), undertaken by the Rakiura Māori people of southern New Zealand, is economically and socially integral to their cultural identity. Muttonbirders concerned at ensuring that the hunt remains viable for coming generations have provided catch records to help ascertain historic trends in hunt success. Analysis of eight catch diaries for a 67-year period demonstrates considerable consistency across diaries in the variability of hunt success, as measured by annualized mean daily hunt tallies. A conservative estimate of the overall annual decline in hunt success is -1.89% (95% CI: -1.14% to -2.65%). Birders' observations of a changing relationship between chick quality and hunt success was evidenced across diaries. Reduced hunt success from the 1990s indicates that possible adult "knockdowns" and/or sustained substantial reductions in breeding proportions have occurred. Chick size has remained constant, suggesting little change in the provisioning environment. Catch per unit effort data, provided by a single diary, confirms a link between variability in annual hunt success and chick abundance. The Pacific Decadal Oscillation (PDO) and the Southern Annular Mode (SAM) are correlated with hunt success and chick size, respectively. Interannual PDO+ (or PDO-) values are correlated with higher (or lower) tallies, whereas SAM+ (or SAM) values are associated with larger (or smaller) chick size. Uncertainty in the relationship between the breeding Sooty Shearwater population, chick catch, and environmental perturbation in their feeding grounds could be reduced with the inclusion of hunt time in all diary records. Ongoing prolonged decline in a top-trophic-level predator such as the Sooty Shearwater raises serious concern that long-term oceanic changes have been occurring and that long-term sustainability of muttonbirding is in doubt.
新西兰南部拉基欧拉（Rakiura）毛利人每年都会猎取蓝企鹅（灰鹱幼鸟），这对于他们的文化认同来说具有经济和社会双重重要性。猎人们为了确保狩猎活动在未来几代人中得以持续，提供了捕捞记录，以帮助确定狩猎成功的历史趋势。对 67 年来 8 本捕捞日记的分析表明，在以年化平均每日狩猎数量衡量的狩猎成功率方面，不同日记之间存在相当大的一致性。对狩猎成功率整体年度下降的保守估计为-1.89%（95%置信区间：-1.14%至-2.65%）。猎人们观察到雏鸟质量与狩猎成功率之间的关系发生了变化，这一点在各个日记中都有体现。20 世纪 90 年代以来狩猎成功率的下降表明，可能出现了成年鸟类的“击倒”现象，或者繁殖比例持续大幅下降。雏鸟的体型保持不变，这表明供应环境几乎没有变化。一份日记提供的每单位捕捞努力数据证实了年度狩猎成功率和雏鸟数量之间的联系。太平洋十年涛动（PDO）和南极环状模式（SAM）分别与狩猎成功率和雏鸟大小相关。PDO+（或 PDO-）值与较高（或较低）的狩猎数量相关，而 SAM+（或 SAM）值与较大（或较小）的雏鸟大小相关。如果将狩猎时间包含在所有日记记录中，就可以减少繁殖蓝灰鹱种群、雏鸟捕捞量以及其觅食地环境干扰之间关系的不确定性。像灰鹱这样的顶级捕食者的持续减少令人严重关切，因为这表明长期的海洋变化一直在发生，蓝灰鹱狩猎的长期可持续性值得怀疑。
