Habitat restoration efforts in the upper San Francisco Estuary, including the Sacramento–San Joaquin Delta, California, move forward, despite a paucity of information on the environmental requirements of many targeted species. The endemic delta smelt Hypomesus transpacificus, protected under the federal Endangered Species Act, is a primary focus of those efforts despite uncertainties regarding many aspects of its relationship with the estuary’s physical and biotic resources. Here we use time-series data from 4 trawl surveys and data on environmental attributes collected from throughout the delta smelt’s distribution to identify ranges of conditions acceptable to delta smelt for each of 5 environmental attributes: water-body type, temperature, turbidity, salinity, and prey availability. Low turbidity and elevated water temperatures render a large portion of the estuary seasonally unsuitable for delta smelt. Within areas in which water quality is suitable, patterns of delta smelt occurrences indicate that habitat is found in subregions where channels of intermediate depth adjoin shallow water. In certain subregions, conditions are inadequate for at least one of the environmental attributes for periods up to several months. We suggest a habitat-restoration strategy that can achieve adequate habitat conditions for delta smelt regardless of through-Delta flow levels, and which can be carried out at a number of locations, but not necessarily the same locations, during each life stage.

中文翻译：

---

使用亲和性分析指导濒危三角洲冶炼的栖息地恢复和增强

尽管缺乏有关许多目标物种的环境要求的信息，但旧金山河口上游（包括加利福尼亚州萨克拉门托-圣华金三角洲）的栖息地恢复工作仍在继续。受联邦《濒危物种法》保护的地方性三角洲跨太平洋三角洲是这些努力的主要重点，尽管其与河口物理和生物资源关系的许多方面存在不确定性。在这里，我们使用来自 4 次拖网调查的时间序列数据和从整个 delta 冶炼分布中收集的环境属性数据来确定 delta 冶炼可接受的 5 个环境属性的条件范围：水体类型、温度、浊度、盐度、和猎物的可用性。低浊度和升高的水温使得大部分河口季节性不适合三角洲冶炼。在水质适宜的区域内，三角洲冶炼出现的模式表明栖息地位于中等深度通道与浅水相邻的子区域。在某些次区域，在长达数月的时间里，至少一种环境属性的条件不足。我们建议一种栖息地恢复策略，无论通过三角洲的流量水平如何，都可以为三角洲冶炼提供足够的栖息地条件，并且可以在每个生命阶段的多个位置进行，但不一定在相同的位置。三角洲冶炼出现的模式表明，栖息地位于中等深度的河道与浅水相邻的次区域。在某些次区域，至少在长达几个月的时间里，条件不适合至少一种环境属性。我们建议一种栖息地恢复策略，无论通过三角洲的流量水平如何，都可以为三角洲冶炼提供足够的栖息地条件，并且可以在每个生命阶段的多个位置进行，但不一定在相同的位置。三角洲冶炼出现的模式表明，栖息地位于中等深度的河道与浅水相邻的次区域。在某些次区域，在长达数月的时间里，至少一种环境属性的条件不足。我们建议一种栖息地恢复策略，无论通过三角洲的流量水平如何，都可以为三角洲冶炼提供足够的栖息地条件，并且可以在每个生命阶段的多个位置进行，但不一定是相同的位置。