Collaborative Research: BEST Synthesis: Integration and modeling of spatial-temporal variation in vital rates for euphausiids in eastern Bering Sea: Implications for demographics

磷虾是连接白令海东部低营养水平鱼类的关键环节，但对磷虾生长和生命率的了解非常有限。解决这些差距的基础信息一直是BEST-BSIERP野外项目的一个重要重点，该项目收集了几种绿腹草物种的个体生长速度和放牧的空间明确信息。相关的活动是利用新的生化方法来研究大尺度的年龄结构。为了最大限度地利用这些数据集，我们提供了资金，集中精力整合和综合这些数据，以估计不同区域（内大陆架、中大陆架和外大陆架）的增长率和生命率，并建立温带生物种群动态模型，以了解其人口结构。这些项目将(1)描述不同水文条件下黄腹小鲵分布的空间变化；(2)综合黄腹小鲵人口结构的空间变化，包括年龄和长度频率；(3)建立黄腹小鲵种群动态和二次生产模型；(4)利用空间结构统计模型研究捕食如何影响生命率；(5)对两种重要物种的生活史和种群动态进行比较。一个分布更广的物种，Thysanoessa raschii，和一个主要居住在外大陆架的物种，T. longipes。研究结果将在不同的水文条件如何通过改变白蛉种群的生长和生命率来影响其人口结构的背景下进行综合。了解不同的水文条件如何影响它们的生长和生命率以及人口结构，将有助于更好地了解这些条件的大规模变化如何影响黄颡鱼种群以及对更高营养水平的潜在影响。在美国，白令海生态系统提供了大约一半的商业海产品，也为自给自足的渔民提供了重要的资源。过去曾发生过这些种群的重大波动，这与观察到的白令海水文条件的变化有关。该项目的结果将表明白令海的食物网可能被这种水文变化所改变的机制。

Euphausiids (krill) are a critical link connecting lower trophic levels to fish in the eastern Bering Sea, yet knowledge of euphausiid growth and vital rates is very limited. Fundamental information to address these gaps has been an important focus of the BEST-BSIERP field program, which has collected spatially explicit information on individual growth rates and grazing for several euphausiid species. Related activities are addressing broad scale age structure using new biochemical approaches for euphausiids. To make the best use of these multiple data sets, funds are provided for a focused effort to integrate and synthesize these data to estimate growth and vital rates for different regions (inner, middle, and outer shelf), and model euphausiid population dynamics to understand their demographic structure. The PIs will (1) describe spatial variations in the distribution of euphausiids in relation to different hydrographic conditions, (2) synthesize spatial variations in their demographic structure, including age and length frequency, (3) model euphausiid population dynamics and secondary production, (4) examine how predation may impact vital rates using spatial-structured statistical models, and (5) produce a comparison of life history and population dynamics of two important species: a species with broader distribution, Thysanoessa raschii, and a species primarily resident over the outer shelf, T. longipes. Results will be synthesized in the context of how the varying hydrographic conditions may impact the demographic structures of euphausiid populations by changing their growth and vital rates. Understanding how varying hydrographic conditions influence their growth and vital rates and demographic structure will lead to better understanding of how large scale changes in these conditions would influence euphausiid populations and potential impacts on higher trophic levels.The Bering Sea ecosystem provides roughly half the commercial seafood landings in the United States, as well as significant resources for subsistence fishermen. Major fluctuations in these stocks have occurred in the past and been associated with variations in the observed hydrographic conditions of the Bering Sea. The results of this project will indicate mechanisms by which the food web of the Bering Sea may be modified by such hydrographic variations.