This study applied a previously used Lagrangian individual‐based model (IBM) for sardine in the Southern Benguela to an improved and more robust hydrodynamic model to investigate whether a more representative spatial coverage, greater horizontal and vertical resolution, more realistic winds and improved representation of mesoscale features such as eddies and filaments would give different results for transport and retention of early life stages. Despite major differences between the old and new hydrodynamic models, overall the IBM results were quite similar to the previous southern Benguela sardine IBM study. This surprising result indicates that it is the macroscale circulation features resolved by the two hydrodynamic models that are controlling transport and retention of sardine early life stages. The contribution of transient mesoscale features such as eddies and filaments appears to be less important when transport patterns are averaged over the 21‐year‐long experiment. Another aim of this study was to better estimate the contribution of south coast spawning to west coast sardine recruitment. This was possible because of an eastward extension of the geographical domain of the new hydrodynamic model which provided a more realistic representation of the south coast spawning ground. Three main spawning and nursery area systems, similar to those identified in the previous sardine IBM, were identified: west coast and west coast (WC‐WC), south coast and west coast (SC‐WC), and south coast and south coast (SC‐SC). Spawning area proved to be an important determinant of modelled retention and transport success, with spawning depth also playing an important role on the west coast. The main difference observed from the previous study was an increase in the average percentage of particles released on the south coast and transported to the west coast (P₀, 17.4%). This indicates more connectivity between the southern and western sardine stocks than previously thought and is therefore important for fishery management. Standardized anomalies from the modelled retention/transport were compared with recruitment estimates from stock assessment models but there was no correlation between the two sets of anomalies. However, a significant correlation was observed between the modelled retention/transport anomalies for the west coast and total cumulative upwelling anomalies for the Southern Benguela (r = −0.67, p < .001).

中文翻译：

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使用高分辨率的IBM调查南非以外的两个沙丁鱼种群之间的连通性：沙丁鱼卵的保留和运输成功

这项研究将先前使用的拉格朗日基于个人的沙丁鱼沙丁鱼模型（IBM）应用于改进和更强大的水动力模型，以研究是否更具代表性的空间覆盖范围，更大的水平和垂直分辨率，更逼真的风向和改善的沙尘暴表示。中尺度特征（例如涡流和细丝）将为早期生命阶段的运输和保留提供不同的结果。尽管新旧水动力模型之间存在重大差异，但IBM的总体结果与先前南部本格拉沙丁鱼IBM的研究非常相似。这一令人惊讶的结果表明，正是沙丁鱼早期生命阶段的两个流体动力学模型所解析的宏观循环特征。当在21年的实验中对运输模式进行平均时，瞬时中尺度特征（如涡流和细丝）的贡献似乎不那么重要。这项研究的另一个目的是更好地估计南海岸产卵对西海岸沙丁鱼补充的贡献。之所以可能这样做，是因为新的水动力模型的地理范围向东扩展，可以更真实地表示南海岸产卵场。与以前的沙丁鱼IBM所识别的系统类似，确定了三个主要产卵区和育苗区系统：西海岸和西海岸（WC-WC），南海岸和西海岸（SC-WC）以及南海岸和南海岸（ SC‐SC）。产卵面积被证明是建模保留和运输成功的重要决定因素，产卵深度在西海岸也起着重要作用。与之前的研究发现的主要区别是，在南海岸释放并传输到西海岸的颗粒物的平均百分比有所增加（P₀，17.4％）。这表明南部和西部沙丁鱼种群之间的联系比以前想象的要多，因此对于渔业管理很重要。将来自建模的保留/运输的标准化异常与来自库存评估模型的招聘估计值进行了比较，但是两组异常之间没有相关性。但是，在模拟的西海岸滞留/输运异常与南本格拉的总累积上升流异常之间观察到显着相关性（r  = -0.67，p  <.001）。