ABSTRACT: Comparison of historical and current data are critical in establishing population trends for imperiled taxa. In this paper we revisit the status of the Bayou darter Nothonotus rubrum, an endemic fish restricted to the Bayou Pierre river system, Mississippi, USA. The Bayou Pierre has experienced substantial geomorphic change in the past century, leading to questions about persistence of this imperiled species. We employed historical field notes and museum records to identify collection localities, and we resampled 32 of these localities using methodologies comparable to the original samples. We further sampled an additional 10 sites with similar methodologies to fill in spatial data gaps. Rates of capture and numbers of individuals were similar between historical and contemporary samples; however, collections with multiple individuals in contemporary samples were largely restricted to the upstream periphery of their historical distribution. Qualitative comparisons of numbers of individuals caught over several decades using variable methodology suggest that declines in abundances have happened since the species was first described. Bayou darter occupancy was positively related to stream link magnitude (beta estimate = 3.07), and N-mixture modeling estimated contemporary abundance at 7.36 ± 3.83 individuals per site. Bayou darter counts were negatively related to variance in kilometer-scale stream elevation (beta estimate = -0.60). Our results suggest that this species remains imperiled and is experiencing a declining range, and that continued efforts to study and monitor this species, and to reduce geomorphic change in the system, are merited.

中文翻译：

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在地貌活跃的流域中，狭窄的地方特有种的“巴豆”射手的状态得到了更新

摘要：历史数据和当前数据的比较对于确定受威胁的分类单元的人口趋势至关重要。在本文中，我们重新审视了Bayou darter Nothonotus rubrum的状况。是一种仅限于美国密西西比州贝尤皮埃尔河系的地方性鱼类。在过去的一个世纪中，巴约皮埃尔（Bayou Pierre）经历了重大的地貌变化，从而引发了对这种濒临灭绝物种的持久性的质疑。我们采用了历史田野记录和博物馆记录来识别收藏地点，并使用与原始样本相当的方法对其中32个地点进行了重新采样。我们还使用相似的方法进一步采样了另外10个站点，以填补空间数据空白。历史和当代样本之间的捕获率和个体数量相似。但是，当代样本中有多个个体的集合在很大程度上局限于其历史分布的上游边缘。使用可变方法对几十年来捕获的个体数量进行定性比较表明，自首次描述该物种以来，丰度开始下降。Bayou darter占用与流域链接大小呈正相关（beta估计= 3.07），并且N混合模型估计每个站点的当代丰度为7.36±3.83个个体。Bayou突进计数与公里尺度河高程的变化负相关（beta估计= -0.60）。我们的结果表明，该物种仍然处于绝种状态，并且范围不断缩小，值得继续研究和监测该物种，并减少系统的地貌变化。