Point Blue Conservation Science, Petaluma, CA, United States of America.
biota.earth, Berkeley, CA, United States of America.
PLoS One. 2020 Jul 7;15(7):e0235603. doi: 10.1371/journal.pone.0235603. eCollection 2020.
As global ocean-bound commerce increases, managing human activities has become important in reducing conflict with threatened wildlife. This study investigates environmental factors determining abundance and distribution of blue whales (Balaenoptera musculus), humpback whales (Megaptera novaeangliae) and their prey (Euphausia pacifica and Thysanoessa spinifera) in central California. We provide insights into environmental drivers of the ecology and distribution of these species, model whale distributions and determine coincident hotspots of whales and their prey that will help decrease human threats to whales and protect critical feeding habitat. We developed separate predictive models of whale abundances (using negative binomial regression on count data) and krill abundance (using a two-part hurdlemodel combining logistic and negative binomial regressions) over a 14 year period (2004-2017). Variables included in situ surface and midwater oceanographic measures (temperature, salinity, and fluorescence), basin-scale climate indices, and bathymetric- and distance-related data. Predictions were applied to 1 km2 cells spanning the study area for May, June, July, and September during each of the 14 years of surveys to identify persistent distribution patterns. Both whales and krill were found to consistently use the northeast region of Cordell Bank, the Farallon Escarpment, and the shelf-break waters. The main identified blue whale hotspots were also krill hotspots, while co-occurrence was more limited and varied seasonally for humpback whales and krill. These results are valuable in identifying patterns in important areas of ecological interaction to assist management of whales. Areas north of Cordell Bank are of particular management concern since they overlap with the end of the San Francisco Bay northern shipping lane. Our findings can help decrease threats to whales, particularly in important foraging areas, by supporting implementation of vessel management and informing potential conflicts with other human uses.
随着全球海洋贸易的增加，管理人类活动对于减少与受威胁野生动物的冲突变得尤为重要。本研究调查了影响加利福尼亚中部蓝鳍金枪鱼（Balaenoptera musculus）、座头鲸（Megaptera novaeangliae）及其猎物（Euphausia pacifica 和 Thysanoessa spinifera）丰度和分布的环境因素。我们深入了解了这些物种生态和分布的环境驱动因素，构建了鲸鱼的分布模型，并确定了鲸鱼及其猎物的热点区域，这将有助于减少人类对鲸鱼的威胁并保护关键的觅食栖息地。我们使用负二项回归（count data）和两部分障碍模型（结合逻辑斯蒂回归和负二项回归），分别建立了 14 年（2004-2017 年）期间鲸鱼丰度和磷虾丰度的预测模型。所纳入的变量包括原位海面和中层海洋测量（温度、盐度和荧光）、流域尺度气候指数以及水深和距离相关数据。我们将预测结果应用于研究区域的 1km2 单元格，以确定每种调查年份的 5 月、6 月、7 月和 9 月的持续分布模式。研究发现，鲸鱼和磷虾都持续使用 Cordell Bank 的东北部、Farallon Escarpment 和陆架坡水域。主要的蓝鳍金枪鱼热点区域也是磷虾热点区域，而座头鲸和磷虾的共存热点则更为有限且随季节变化。这些结果对于确定重要生态相互作用区域的模式非常有价值，可以帮助管理鲸鱼。Cordell Bank 以北的区域尤其需要管理，因为这些区域与旧金山湾北部航道的末端重叠。我们的研究结果可以帮助减少鲸鱼面临的威胁，特别是在重要的觅食区域，从而支持实施船只管理并为其他人类活动可能产生的冲突提供信息。
