The estimation of growth rates in young herring larvae (Clupea harengus) in the field can be difficult since the primary increments in the otoliths may not be discernible or formed at a daily level. Likewise, the estimation of mortality rates of fish larvae in the field is very difficult to achieve, especially in a rigorous quantitative manner. Here we suggest the use of a stage-based proxy of feeding success, growth, and potential survival or mortality risk of field caught larvae. The stage-based proxy is derived based on observations from previous laboratory studies where larvae successfully completing start-feeding on external food sources will advance through the early development stages, while those that do not (unsuccessful larvae), remain and accumulate in the development stage preceding first feeding. The relative occurrence of larvae in the early development stages is therefore expected to reflect feeding conditions of the larvae, with higher ratios of unsuccessful larvae indicative of poor feeding success and higher mortality risk. Using field data on Norwegian Spring Spawning herring we document that the relative occurrence of larvae in the late non-feeding stage are significantly higher at lower average zooplankton concentrations, in line with our predictions that this novel approach of using a stage-based proxy could be a useful indication of feeding success, growth and mortality in the field. Further, there was a significant interaction effect with ambient temperature, with the ratio being higher at low zooplankton concentrations at higher temperatures. This study also suggests that these findings are not population specific as the same accumulation of non-feeding larvae in the late non-feeding stage was observed in laboratory reared larvae of both autumn and spring spawning herring populations. This article is protected by copyright. All rights reserved.

中文翻译：

---

发育阶段分布作为第一次饲养挪威春季产卵鲱鱼幼虫的饲养成功和生长的代理

由于耳石的主要增量可能无法辨别或在日常水平上形成，因此在田间估计幼鲱鱼幼虫 (Clupea harengus) 的增长率可能很困难。同样，很难估计田间鱼类幼虫的死亡率，尤其是在严格的定量方式下。在这里，我们建议使用基于阶段的代理来衡量田间捕获的幼虫的饲养成功率、生长情况以及潜在的存活或死亡风险。基于阶段的代理是基于之前实验室研究的观察得出的，其中成功完成对外部食物来源的开始取食的幼虫将进入早期发育阶段，而那些没有（不成功的幼虫）则在发育阶段保留并积累在第一次喂食之前。因此，预计早期发育阶段幼虫的相对发生率反映了幼虫的摄食条件，不成功幼虫的比例越高，表明摄食成功率低，死亡风险越高。使用挪威春季产卵鲱鱼的现场数据，我们记录了非摄食晚期幼虫的相对发生率在较低的平均浮游动物浓度下显着更高，这与我们的预测一致，即这种使用基于阶段的代理的新方法可能是田间饲养成功、生长和死亡率的有用指标。此外，与环境温度存在显着的交互作用，在较高温度下，在低浮游动物浓度下，该比率更高。这项研究还表明，这些发现不是特定种群的，因为在秋季和春季产卵鲱鱼种群的实验室饲养幼虫中观察到了相同的非进食后期非进食幼虫的积累。本文受版权保护。版权所有。