The historic extirpation and subsequent recovery of sea otters (Enhydra lutris) have profoundly changed coastal social-ecological systems across the northeastern Pacific. Today, the conservation status of sea otters is informed by estimates of population carrying capacity or growth rates independent of human impacts. However, archaeological and ethnographic evidence suggests that for millennia, complex hunting and management protocols by Indigenous communities limited sea otter abundance near human settlements to reduce the negative impacts of this keystone predator on shared shellfish prey. To assess relative sea otter prevalence in the Holocene, we compared the size structure of ancient California mussels (Mytilus californianus) from six archaeological sites in two regions on the Pacific Northwest Coast, to modern California mussels at locations with and without sea otters. We also quantified modern mussel size distributions from eight locations on the Central Coast of British Columbia, Canada, varying in sea otter occupation time. Comparisons of mussel size spectra revealed that ancient mussel size distributions are consistently more similar to modern size distributions at locations with a prolonged absence of sea otters. This indicates that late Holocene sea otters were maintained well below carrying capacity near human settlements as a result of human intervention. These findings illuminate the conditions under which sea otters and humans persisted over millennia prior to the Pacific maritime fur trade and raise important questions about contemporary conservation objectives for an iconic marine mammal and the social-ecological system in which it is embedded.

海獭（Enhydra lutris）的历史性灭绝和随后的恢复已经深刻改变了太平洋东北部的沿海社会生态系统。今天，海獭的保护状况是通过对独立于人类影响的种群承载能力或增长率的估计来确定的。然而，考古学和人种学证据表明，几千年来，土著社区复杂的狩猎和管理协议限制了人类住区附近的海獭数量，以减少这种主要捕食者对共享贝类猎物的负面影响。为了评估全新世海獭的相对流行率，我们比较了古代加利福尼亚贻贝（Mytilus californianus ）的大小结构。) 从太平洋西北海岸两个地区的六个考古遗址，到现代加利福尼亚贻贝在有和没有海獭的地方。我们还量化了加拿大不列颠哥伦比亚省中央海岸八个地点的现代贻贝大小分布，这些地点的海獭占用时间各不相同。贻贝大小光谱的比较表明，在长期没有海獭的地方，古代贻贝大小分布与现代大小分布更相似。这表明，由于人为干预，全新世晚期海獭在人类住区附近的承载能力远低于承载能力。