Steller and California sea lion count and diet data in northwest Washington, 2010-2013

In this submission, we share data collected on Steller (Eumetopias jubatus) and California sea lion (Zalophus californianus) in northwest Washington year round from 2010-2013. Our primary objectives were to characterize the diets of Steller and California sea lions and to determine if the sympatric species compete for the same prey resources. We also wanted to determine how much prey each of the sea lions were eating. To determine prey consumption we collected data on the abundance of California and Steller sea lions during surveys. Generally only male California sea lions are present in northwest Washington. For Steller sea lions, all age groups are present and so we also counted by demographic group. We found that Steller and California sea lions have significant dietary niche overlap as the species utilize very similar assemblages of prey. We developed a procedure for estimating prey consumption by the sea lions using published data and our counts and have made our code publically available at https://github.com/jscordino/NW-WA-Sea-Lion-Prey-Consumption. We found that Steller sea lions ate roughly 11,000 metric tons of prey per year from 2010-2013 and that California sea lions ate roughly 9,500 metric tons of prey. A manuscript of our results has been submitted to Fishery Bulletin in April of 2021.

在本项提交中，我们分享了自2010年至2013年期间对西北华盛顿地区的 Stellar海豹（Eumetopias jubatus）和加州海狮（Zalophus californianus）全年收集的数据。我们的主要目标是描绘Stellar海豹和加州海狮的饮食结构，并探究两种物种是否为了相同的猎物资源而发生竞争。此外，我们还旨在确定每只海狮所摄取的猎物量。为了确定猎物消耗量，我们在调查期间收集了加州和Stellar海狮的丰度数据。通常情况下，西北华盛顿地区仅存在雄性加州海狮。对于Stellar海狮而言，所有年龄组均有所分布，因此我们还按人口统计学群体进行了计数。我们发现，Stellar海狮和加州海狮在食物生态位上存在显著的重叠，因为两种物种利用了极为相似的猎物群体。我们基于已发表的数据和我们的计数数据，开发了一套估算海狮猎物消耗量的程序，并将我们的代码公开发布于https://github.com/jscordino/NW-WA-Sea-Lion-Prey-Consumption。我们发现，从2010年至2013年，Stellar海狮每年大约消耗了11,000公吨的猎物，而加州海狮的消耗量约为9,500公吨。我们的研究成果手稿已于2021年4月提交至《渔业通报》杂志。