Trends in abundance and current status of harbor seals in oregon: 1977-2003
Trends in abundance and current status of harbor seals in oregon: 1977-2003
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DOI：
10.1111/j.1748-7692.2005.tb01258.x
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发表时间：
2005-10-01
影响因子：
2.3
通讯作者：
Laake, J
中科院分区：
文献类型：
--
作者：
Brown, RE;Wright, BE;Laake, J
1977年至2003年，采用航空摄影方法对俄勒冈州斑海豹（Phoca vitulina richardii）的分布和数量进行了监测。在繁殖期间，每年都会对岸上的海豹进行计数。以非幼崽（成虫和亚成虫）的年平均数量作为种群规模的指标，并采用指数（密度无关）和广义逻辑（密度依赖）生长模型对数量趋势进行建模。模型采用最大似然拟合，并采用赤池信息准则进行评价。俄勒冈州斑海豹种群动态最好用广义logistic模型来描述。在1972年《海洋哺乳动物保护法》的保护下，它们的数量开始增长，直到20世纪90年代初稳定下来。在2002年繁殖期内，所有年龄组海豹的绝对丰度估计为10087只（95%可信区间为8445-12046只）。目前俄勒冈州斑海豹的预测种群规模高于其估计的最大净生产力水平，因此在其最佳可持续种群范围内。我们推测，最近东太平洋海洋生产力的增加可能会导致俄勒冈州海港海豹数量的增加和承载能力的增加。
The distribution and abundance of harbor seals (Phoca vitulina richardii) in Oregon were monitored from 1977 to 2003 by aerial photographic surveys. Harbor seals on shore were counted each year during the reproductive period. Mean annual counts of non-pups (adults and subadults) were used as an index of population size and the trend in the counts was modeled using exponential (density-independent) and generalized logistic (density-dependent) growth models. Models were fit using maximum likelihood and evaluated using Akaike's Information Criterion. The population dynamics of harbor seals in Oregon were best described by the generalized logistic model. The population grew following protection under the Marine Mammal Protection Act of 1972 until stabilizing in the early 1990s. The estimated absolute abundance of harbor seals (all age classes) during the 2002 reproductive period was 10087 individuals (95% confidence interval was 8445-12046 individuals). The current predicted population size for harbor seals in Oregon is above its estimated maximum net productivity level and hence within its optimum sustainable population range. We speculate that recent increases in ocean productivity in the eastern Pacific Ocean may lead to an increase in carrying capacity and renewed growth in Oregon's harbor seal population.