Oregon State University Department of Fisheries and Wildlife, Oregon Department of Fish and Wildlife, Corvallis, Oregon, United States of America.
Alaska SeaLife Center, Seward, Alaska, United States of America.
PLoS One. 2019 Jul 31;14(7):e0219484. doi: 10.1371/journal.pone.0219484. eCollection 2019.
There are approximately 10,000-12,000 Pacific harbor seals (Phoca vitulina richardii) inhabiting the Oregon coast, and unlike other species of pinnipeds in this region, are reliably present year-round. Despite this, and drastic rebounds in population since the enactment of the Marine Mammal Protection Act, limited data is available for the present period regarding their space use at sea, and within estuarine, riverine, or bay areas within the state.
To examine site-based differences in space use for 24 adult Pacific harbor seals captured and outfitted with satellite transmitters at two predominant haulout sites on the Oregon Coast, USA.
We captured 24 adult harbor seals from two haulout sites on the Central Oregon coast between September 2014-16 and fitted them with external Wildlife Computers SPOT5 satellite transmitters to track movement. Using state-space modeled locations derived from satellite telemetry data, we evaluated spatial behavior of these animals using a correlated random walk model via R package crawl. Kernel density estimation was subsequently used to calculate home range and core area for each animal. Percent use of open ocean habitat versus use of estuaries, rivers and bays was quantified, as was an initial examination of presence within five newly-established marine reserves in Oregon. Examination of haulout site-related differences in spatial behavior were examined for seals captured in Netarts and Alsea Bays, Oregon and haul out behavior related to time of day, season, and tidal level was also investigated.
The average individual home range for seals was 364.47 ± 382.87 km2 with seals captured in Alsea bay demonstrating a significantly higher home range area than those captured in Netarts Bay. Alsea bay seals also tended to range farther from shore than Netarts Bay animals. The average calculated core area for seals encompassed on average 29.41 ± 29.23 km2 per animal, however the home range of one animal was so small, core area could not be calculated. Use of marine reserves was limited for animals in this study, representing less than 2% of locations with a majority occurring in Cape Perpetua Marine Reserve and North Marine Protected Area. Seals were more likely to haul out during low tides and periods of low light (dusk, night and dawn), and hauling out behavior increased in winter months.
These findings demonstrate the first major documentation of space use of harbor seals in the state for nearly three decades, and lends itself to future comparison and formation of mechanistically-based hypotheses for behavior of a common marine mammal in the highly productive northern California Current System.
俄勒冈海岸大约有 10000-12000 只太平洋港海豹（Phoca vitulina richardii）栖息，与该地区其他鳍足类动物不同的是，它们全年都可靠地存在。尽管如此，自《海洋哺乳动物保护法》颁布以来，该物种的数量急剧反弹，但目前关于它们在海上和该州内河口、河流或海湾地区的空间利用的可用数据有限。
检查在美国俄勒冈海岸两个主要登陆点捕获并配备卫星发射器的 24 只成年太平洋港海豹的基于地点的空间利用差异。
我们于 2014 年 9 月至 2016 年 9 月在俄勒冈州中部海岸的两个登陆点捕获了 24 只成年港海豹，并为它们配备了外部野生动物计算机 SPOT5 卫星发射器来跟踪它们的运动。使用源自卫星遥测数据的状态空间模型位置，我们通过 R 包 crawl 使用相关随机游走模型评估这些动物的空间行为。随后使用核密度估计来计算每个动物的活动范围和核心区域。量化了开阔海洋生境的利用百分比与河口、河流和海湾的利用百分比，以及俄勒冈州五个新建立的海洋保护区内的存在情况的初步研究。还研究了在俄勒冈州的阿尔西湾和内塔斯湾捕获的海豹的登陆点相关空间行为差异，并研究了与一天中的时间、季节和潮汐水平有关的登陆行为。
海豹的平均个体活动范围为 364.47 ± 382.87 km2，在阿尔西湾捕获的海豹活动范围明显大于在内塔斯湾捕获的海豹。阿尔西湾的海豹也往往比内塔斯湾的动物离海岸更远。平均计算出的海豹核心区域平均每个动物涵盖 29.41 ± 29.23 km2，但一只动物的活动范围如此之小，无法计算核心区域。在这项研究中，动物对海洋保护区的利用有限，不到位置的 2%，大部分发生在卡佩佩图亚海洋保护区和北海洋保护区。海豹更有可能在低潮和低光照（黄昏、夜间和黎明）期间上岸，并且在冬季上岸行为增加。
这些发现首次对近三十年来该州海豹空间利用情况进行了重要记录，为未来对北加利福尼亚当前系统中常见海洋哺乳动物的行为进行基于机制的假设形成提供了依据。
