Maximum densities of juvenile river herring (Alewife Alosa pseudoharengus and Blueback Herring A. aestivalis) vary among freshwater lakes, likely due to densities of adult spawners. Differences in habitat availability and lake water quality may also contribute to variation in juvenile river herring productivity between populations, yet these relationships have not been tested across a large geographic scope. In this study we investigated relationships between juvenile river herring densities and (1) spawning adult river herring densities, (2) lake habitat availability, and (3) lake water quality in 29 freshwater lakes in the northeastern USA. Purse seines were used at night to sample juvenile river herring monthly in June–August 2014 and 2015, with concurrent collection of lake‐specific physical (e.g., lake surface area, mean depth, depth to thermocline), chemical (e.g., nitrogen, phosphorus, dissolved organic carbon [DOC]), and biological (chlorophyll a, adult spawning density) data. Spawning adult density (number of adults per surface area of lake) explained 66.6% of the variation in juvenile densities using a generalized additive model. Juvenile densities increased with increasing adult density, peaking at roughly 1,000 adults/ha, and then declined at higher adult densities, suggesting a limit to carrying capacity in juvenile production. Linear mixed‐effects models revealed that differences in water quality and habitat across lakes explained additional variation in juvenile densities. Specifically, DOC was negatively related to juvenile densities, suggesting that DOC limits the amount of suitable, well‐oxygenated epilimnion habitat available to juvenile river herring in late summer. Our results can be used to help understand expected juvenile production based on adult density within a lake, to inform expectations about juvenile growth and survival, and to understand the mechanisms for how changes in habitat availability and water quality affect river herring populations.

中文翻译：

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感受挤压：成年游猎规模和栖息地可利用性限制了湖泊中少年河鲱鱼的密度

少年河鲱鱼的最大密度（Alewife Alosa pseudoharengus和Blueback Herring A. aestivalis）在淡水湖之间有所不同，这可能是由于成年产卵者的密度所致。栖息地可用性和湖泊水质的差异也可能导致种群之间少年河鲱鱼生产力的差异，但是尚未在较大的地理范围内检验这些关系。在这项研究中，我们调查了美国东北部29个淡水湖泊中幼鱼鲱鱼密度与（1）产卵成年鲱鱼鲱鱼密度，（2）湖泊栖息地可利用性和（3）湖泊水质之间的关系。在2014年6月至2014年8月期间，每月晚上使用围网围网捕捞幼鱼，同时收集特定于湖泊的物理物质（例如，湖泊表面积，平均深度，热跃层深度），化学物质（例如，氮，磷） ，溶解有机碳[DOC]）和生物（叶绿素）一个，成年产卵密度）数据。产卵的成虫密度（每湖表面积的成虫数量）使用广义加性模型解释了幼虫密度变化的66.6％。少年密度随成虫密度的增加而增加，最高时约为每千名成年人/公顷，然后随着成虫密度的增加而下降，这表明幼鱼生产的承载能力受到限制。线性混合效应模型表明，湖泊之间水质和生境的差异解释了幼鱼密度的其他变化。具体而言，DOC与幼虫密度呈负相关，这表明DOC限制了夏末鲱鱼可利用的，适当充氧的ated生动物栖息地的数量。我们的结果可用于帮助了解基于湖泊内成虫密度的预期幼鱼产量，