Capelin (Mallotus villosus) is a forage fish and a key species in the Barents Sea (BS). The BS capelin are semelparous and hence only spawn once along the north coasts of Norway and Russia before they die. The age at spawning ranges from 2 to 5 years and the spawning season peaks in March/April but starts in February and lasts until June, and the causes of the variability in timing of spawning are not well understood. Here, we aimed to find out whether early growth is associated with the timing of spawning in BS capelin, both on the individual and population level, and if there is an association between early life growth and the spatial distribution at the nursery areas and feeding grounds. For the analysis, we used an extensive dataset comprising >150 000 otolith growth zone measurements carried out during surveys from 1976 to 2019 both from the spawning and feeding areas. The data from the feeding area showed that capelin with good first-year growth were found in the productive north-west part of the Barents Sea at both age 1 and 2, while capelin with relatively poor first-year growth were typically found in the south-east Barents Sea. The data from the spawning area showed on the individual level that capelin with good first-year growth tend to spawn both at a younger age and earlier in the season. The capelin spawning late in the season were also generally smaller than early spawners. On the population level, a contradictory pattern was observed where the proportion of maturing capelin at age 2 and 3 was negatively correlated with first-year growth indicating that the great variability in year-class strength masks the general effect found at the level of individual fish. Furthermore, first-year growth was positively associated with the abundance of 1-year-old capelin indicating that rapid growth early in life enhances recruitment. On the other hand, first-year growth was strongly negatively correlated with third-year growth suggesting an increased effect of density-dependent growth with age and/or compensatory growth, or reduced growth linked to earlier maturation. In sum, our results show that the first-year growth affects growth, maturation processes, and timing of spawning later in life, thus potentially strongly influencing capelin population dynamics.

毛鳞鱼（Mallotus villosus）是一种饲料鱼，是巴伦支海（BS）的重要物种。BS 毛鳞鱼是半生的，因此在它们死亡之前只会在挪威和俄罗斯的北部海岸产卵一次。产卵年龄为 2 至 5 年不等，产卵季节在 3 月/4 月达到顶峰，但从 2 月开始并持续到 6 月，产卵时间变化的原因尚不清楚。在这里，我们旨在找出早期生长是否与 BS 毛鳞鱼在个体和种群水平上的产卵时间相关，以及早期生长与育苗区和饲养场的空间分布之间是否存在关联. 对于分析，我们使用了包含> 150的广泛数据集 000 耳石生长区测量在 1976 年至 2019 年的调查期间从产卵区和进食区进行。来自饲养区的数据显示，第一年生长良好的毛鳞鱼在 1 龄和 2 龄的巴伦支海西北部多产，而第一年生长相对较差的毛鳞鱼通常在南部发现-东巴伦支海。产卵区的数据显示，在个体层面上，第一年生长良好的毛鳞鱼往往在较年轻的年龄和较早的季节产卵。在季节后期产卵的毛鳞鱼通常也比早期产卵的小。在人口层面，观察到了一种矛盾的模式，即 2 岁和 3 岁成熟毛鳞鱼的比例与第一年的生长呈负相关，这表明年级强度的巨大变化掩盖了在个体鱼水平上发现的一般影响。此外，第一年的生长与 1 岁毛鳞鱼的丰度呈正相关，表明生命早期的快速生长促进了招募。另一方面，第一年的生长与第三年的生长呈强烈负相关，表明密度依赖性生长随年龄和/或补偿性生长的影响增加，或与较早成熟相关的生长减少。总之，我们的结果表明，第一年的生长会影响生长、成熟过程和生命后期产卵的时间，