Somatic growth exerts strong control on patterns in the abundance of animal populations via effects on maturation, fecundity, and survival rates of juveniles and adults. In this paper, we quantify abiotic and biotic drivers of rainbow trout growth in the Colorado River, Arizona, USA, and the resulting impact on spatial and temporal variation in abundance. Inferences are based on ~10,000 observations of individual growth rates obtained through an intensive mark–recapture effort conducted over 5 yrs (2012–2016) in a 130‐km long study segment downstream of Glen Canyon Dam. Prey availability, turbidity‐driven feeding efficiency, and intraspecific competition were the dominant drivers of rainbow trout growth. Discharge, water temperature, and solar insulation were also evaluated but had a smaller influence. Mixed‐effect models explained 79–82% of the variability in observed growth rates, with fixed covariate effects explaining 79–87% of the total variation in growth parameters across five reaches and 18 quarterly sampling intervals. Reductions in growth owing in part to a phosphorous‐driven decline in prey availability, led to a substantive loss in mass and poor fish condition. This in turn lowered survival rates and delayed maturation, which led to a rapid decline in abundance and later recruitments. Reductions in feeding efficiency, due to episodic inputs of fine sediment from tributaries, and warmer water temperatures, contributed to reduced growth in downstream reaches, which led to more severe declines in abundance. Somatic growth rates increased following the population collapse due to reduced competition, and in the absence of substantive increases in prey availability. Our study elucidates important linkages between abiotic and biotic factors, somatic growth, and vital rates, and demonstrates how variation in somatic growth influences temporal and spatial patterns in abundance.

中文翻译：

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猎物，浑浊和竞争的变化会降低体细胞的生长并导致鱼类种群的崩溃

体细胞生长通过影响幼年和成年动物的成熟度，繁殖力和存活率，对动物种群数量的模式产生强有力的控制。在本文中，我们量化了美国亚利桑那州科罗拉多河虹鳟鱼生长的非生物和生物驱动因素，以及由此对丰度的时空变化的影响。推论是基于在Glen Canyon大坝下游130公里长的研究区域中，通过5年（2012-2016年）的密集标记捕获工作而获得的大约10,000个个体增长率的观察结果。猎物的可获得性，浊度驱动的饲喂效率以及种内竞争是虹鳟生长的主要驱动力。还评估了排放，水温和太阳能隔热性能，但影响较小。混合效应模型解释了所观察到的增长率的79–82％，固定协变量效应解释了五个区域和18个季度采样间隔内生长参数总变化的79–87％。磷减少导致猎物可利用性下降，从而导致生长减少，导致质量大量下降和鱼类状况恶劣。反过来，这降低了成活率并延迟了成熟，从而导致了数量的迅速下降和后来的招聘。由于支流细粒沉积物的间歇性输入以及水温升高，导致进食效率下降，导致下游河段的生长减少，导致丰度进一步下降。竞争减少导致人口崩溃，导致体细胞生长速率增加，并没有大量增加猎物的供应。我们的研究阐明了非生物和生物因素，体细胞生长和生命率之间的重要联系，并证明了体细胞生长的变化如何影响时空格局。