Hinrichsen H-H, von Dewitz B, Dierking J, Haslob H, Makarchouk A, Petereit C, Voss R
GEOMAR - Helmholtz Centre for Ocean Research , Düsternbrooker Weg 20, 24105 Kiel, Germany.
Thünen-Institute of Sea Fisheries , Palmaille 9, 22767 Hamburg, Germany.
R Soc Open Sci. 2016 Jan 13;3(1):150338. doi: 10.1098/rsos.150338. eCollection 2016 Jan.
Environmental conditions may have previously underappreciated effects on the reproductive processes of commercially exploited fish populations, for example eastern Baltic cod, that are living at the physiological limits of their distribution. In the Baltic Sea, salinity affects neutral egg buoyancy, which is positively correlated with egg survival, as only water layers away from the oxygen consumption-dominated sea bottom contain sufficient oxygen. Egg buoyancy is positively correlated to female spawner age/size. From observations in the Baltic Sea, a field-based relationship between egg diameter and buoyancy (floating depth) could be established. Hence, based on the age structure of the spawning stock, we quantify the number of effective spawners, which are able to reproduce under ambient hydrographic conditions. For the time period 1993-2010, our results revealed large variations in the horizontal extent of spawning habitat (1000-20 000 km(2)) and oxygen-dependent egg survival (10-80%). The novel concept of an effective spawning stock biomass takes into account offspring that survive depending on the spawning stock age/size structure, if reproductive success is related to egg buoyancy and the extent of hypoxic areas. Effective spawning stock biomass reflected the role of environmental conditions for Baltic cod recruitment better than the spawning stock biomass alone, highlighting the importance of including environmental information in ecosystem-based management approaches.
环境条件可能对商业开发的鱼类种群（如生活在分布生理极限区域的东波罗的海鳕鱼）的繁殖过程产生了此前未被充分认识的影响。在波罗的海，盐度影响鱼卵的中性浮力，而鱼卵浮力与鱼卵存活率呈正相关，因为只有远离以耗氧为主的海底水层才含有足够的氧气。鱼卵浮力与雌鱼产卵年龄/大小呈正相关。根据在波罗的海的观测，可以建立鱼卵直径与浮力（漂浮深度）之间基于实地的关系。因此，基于产卵群体的年龄结构，我们量化了能够在当前水文条件下繁殖的有效产卵者数量。对于1993 - 2010年期间，我们的结果显示产卵栖息地的水平范围（1000 - 20000平方公里）和依赖氧气的鱼卵存活率（10% - 80%）存在很大差异。有效产卵群体生物量这一新概念考虑了取决于产卵群体年龄/大小结构而存活下来的后代数量，前提是繁殖成功率与鱼卵浮力以及缺氧区域范围相关。有效产卵群体生物量比单独的产卵群体生物量能更好地反映环境条件对波罗的海鳕鱼补充量的作用，突出了在基于生态系统的管理方法中纳入环境信息的重要性。
