Wood Stephanie A, Murray Kimberly T, Josephson Elizabeth, Gilbert James
University of Massachusetts, Boston, Biology Department, Boston, MA, USA.
National Marine Fisheries Service, Woods Hole, MA, USA.
J Mammal. 2020 Feb 21;101(1):121-128. doi: 10.1093/jmammal/gyz184. Epub 2019 Dec 13.
Gray seals were historically distributed along the northeastern coast of the United States, but bounties and lack of protection reduced numbers and they were rarely observed for most of the 20th century. Once protections were enacted, the population started to rebound. Here, we describe the recolonization and recovery of gray seals in the United States, focusing on the re-establishment of pupping sites. We fit individual generalized linear models to various time series (1988-2019) to estimate rates of increase in observed pup counts at four of the more data-rich sites. Annual rate of increase at individual sites ranged from -0.2% (95% : -2.3-1.9%) to 26.3% (95% : 21.6-31.4%). The increase in sites and number of pups born in the United States is driven by population growth and immigration from Canadian colonies and is part of a larger recovery of the Northwest Atlantic population. Wildlife protection, a healthy source population, habitat availability, and species traits that allow for dispersal and high productivity were all important factors in this recovery.
灰海豹历史上分布于美国东北海岸，但赏金制度和缺乏保护导致其数量减少，在20世纪的大部分时间里很少被观察到。一旦实施了保护措施，其数量便开始回升。在此，我们描述了美国灰海豹的重新定居和恢复情况，重点关注繁殖地的重新建立。我们将个体广义线性模型应用于各种时间序列（1988 - 2019年），以估计四个数据较为丰富的地点观察到的幼崽数量的增长率。各个地点的年增长率从 -0.2%（95%置信区间：-2.3 - 1.9%）到26.3%（95%置信区间：21.6 - 31.4%）不等。美国繁殖地数量和出生幼崽数量的增加是由种群增长以及来自加拿大殖民地的移民推动的，并且是西北大西洋种群更大规模恢复的一部分。野生动物保护、健康的源种群、栖息地可利用性以及允许扩散和高繁殖力的物种特性都是这次恢复的重要因素。
