Institute for Marine Ecosystem and Fisheries Science (IMF), University of Hamburg, Hamburg, Germany.
Department of Coastal Systems, Royal Netherlands Institute for Sea Research (NIOZ), Texel, The Netherlands.
J Fish Biol. 2022 Dec;101(6):1428-1440. doi: 10.1111/jfb.15210. Epub 2022 Sep 28.
In marine fishes, the timing of spawning determines the environment offspring will face and, therefore, the chances of early life stage survival. Different waves of Atlantic herring Clupea harengus spawn throughout spring in the western Baltic Sea, and the survival of offspring from early in the season has been low in the most recent decade. The authors assessed changes in egg traits from early, middle and late phases of the spawning season to examine whether seasonal and/or maternal effects influenced embryo survival. At each phase, fertilized eggs of six to eight females were incubated at two temperatures (7 and 13°C), and egg size, fertilization success, mortality and time to hatch were recorded. A compilation of data from 2017 to 2020 spawning seasons indicated that mean total length of females decreased with progression of the season and increasing in situ water temperature. For the sub-set of females used in the laboratory study, early spawners were 7.6% larger and produced 14.2% larger eggs than late-spring spawners. Fertilization success was consistently high (>90%), and mortality to hatch was low (<3%). Neither the former nor latter were influenced by season, but both were influenced by maternity. This significant female effect was, however, not related to any maternal trait measured here (total length, Fulton's condition factor or age). There was no maternal effect on development rate at 7 or 13°C. The results suggest that intrinsic differences among females or among spawning waves are unlikely to markedly contribute to the poor survival observed for progeny from early in the season in this population and point towards other extrinsic factors or processes acting on eggs or early larval stages (e.g., seasonal match-mismatch dynamics with prey) as more likely causes of mortality.
在海洋鱼类中，产卵时间决定了后代所面临的环境，因此也决定了早期生活阶段的生存机会。在波罗的海西部，大西洋鲱鱼 Clupea harengus 会在整个春季分多波次产卵，而最近十年中，春季早期产卵的后代存活率一直较低。作者评估了产卵季节早期、中期和晚期的卵特征变化，以检验季节性和/或母体效应对胚胎存活率的影响。在每个阶段，将 6 到 8 个雌鱼的受精卵在两个温度（7 和 13°C）下孵化，并记录卵的大小、受精成功率、死亡率和孵化时间。2017 年至 2020 年产卵季节的数据综合表明，随着季节的推进和原位水温的升高，雌鱼的平均全长减小。对于在实验室研究中使用的雌鱼子集，早期产卵的雌鱼比春季晚期产卵的雌鱼大 7.6%，产卵也大 14.2%。受精成功率始终很高（>90%），孵化死亡率很低（<3%）。季节和母体都没有影响受精成功率和孵化死亡率，但两者都影响了卵的大小。然而，这种显著的母性效应与这里测量的任何母体特征（全长、Fulton 体质系数或年龄）都没有关系。在 7 或 13°C 时，发育速度没有母体效应。研究结果表明，个体间或产卵波之间的内在差异不太可能显著导致该种群中春季早期产卵后代的存活率较低，这表明其他外部因素或过程对卵或早期幼虫阶段（例如，与猎物的季节性不匹配动态）的影响更可能是导致死亡率的原因。
