Reproductive investment is a central trait for population dynamics and productivity. Fishing and environmental variations are major drivers affecting population structure, dynamics, and adaptation of life-history and behavioural traits. However, those factors are often considered independently, and few studies take into account their joint effect. In this study, we investigate the contribution of environment, fishing pressure, and intra-specific competition to variation in the reproductive investment of the Norwegian spring-spawning herring (Clupea harengus), a stock that has been fished for centuries, and monitored for decades. Reproductive investment and post-spawning weight were affected differently by growth rate (measured as mean age-at-length), sea surface temperature, North Atlantic Oscillation, and spawning stock biomass in periods with no fishing, unselective fishing, and low but size-selective fishing. We hypothesize that those changes can be explained by direct effects of exploitation such as age truncation and changes in migration patterns. Our results highlight how fishing, by affecting population-level dynamics, can modify the impact of environmental variations on life-history traits.

中文翻译：

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鲱鱼繁殖投资的八年适应性变化：环境与剥削的共同作用

生殖投资是人口动态和生产力的核心特征。捕鱼和环境变化是影响种群结构、动态以及生活史和行为特征适应的主要驱动因素。然而，这些因素往往是独立考虑的，很少有研究考虑到它们的共同作用。在这项研究中，我们调查了环境、捕捞压力和种内竞争对挪威春季产卵鲱鱼（Clupea harengus）繁殖投资变化的贡献。)，一种已被捕捞数百年并监测数十年的种群。繁殖投资和产卵后体重受增长率（以平均身长衡量）、海面温度、北大西洋涛动和未捕捞、非选择性捕捞和低但大小的时期产卵种群生物量的影响不同。选择性捕鱼。我们假设这些变化可以用剥削的直接影响来解释，例如年龄截断和迁移模式的变化。我们的结果强调了捕鱼如何通过影响种群水平的动态来改变环境变化对生活史特征的影响。