The brown shrimp,Crangon crangon, is the most important target of the coastal crustacean fisheries in the German Bight. In order to evaluate the relation between the abundance of ovigerous females and larvae in spring and the recruitment success in autumn, we first analysed the seasonal appearance of ovigerous females and larvae from weekly samples throughout 2012. The spawning season in the German Bight extends over several months comprising multiple unsynchronized spawning events. The minimum shares of ovigerous females appeared in early autumn, and the highest shares in late winter bearing mostly early egg stages. We defined the putative start of the reproductive cycle for November when the frequency of ovigerous females started to increase. There was no distinct separation between winter and summer eggs, but a continuous transition between large eggs spawned in winter (the early spawning season) and batches of smaller eggs in spring and summer. Larval densities peaked in April/May. Consequently, regular annual larval surveys from 2013 to 2016 were scheduled for April/May and extended to six transects covering the inner German Bight. Ovigerous females were most abundant in shallow waters above the 20‐m isobaths, which also explained regional differences in abundance between the regions off North Frisia and East Frisia. No relation was obvious between the number of larvae in spring and recruited stock in autumn. Due to the short lifespan of C. crangon, the combination of various abiotic factors and predator presence seems to be the principal parameters controlling stock size.

中文翻译：

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内德湾（北海）褐虾 Crangon crangon 的繁殖和补充：一项年际研究和批判性重新评估

褐虾，Crangon crangon，是德国湾沿岸甲壳类渔业的最重要目标。为了评估春季产卵雌性和幼虫丰度与秋季募集成功率之间的关系，我们首先分析了整个 2012 年每周样本中产卵雌性和幼虫的季节性出现。月包括多个不同步的产卵事件。初秋产卵雌性所占比例最低，冬末产卵期所占比例最高，多为早产卵期。我们定义了 11 月生殖周期的假定开始，当时雌性雌性的频率开始增加。冬蛋和夏蛋之间没有明显的区别，但是在冬季（早期产卵季节）产卵的大卵与春季和夏季的小卵批次之间不断过渡。幼虫密度在 4 月/5 月达到峰值。因此，2013 年至 2016 年的定期年度幼虫调查定于 4 月/5 月进行，并扩展到覆盖德国内湾的六个样带。在 20 米等深线以上的浅水中，有生育能力的雌性最丰富，这也解释了北弗里西亚和东弗里西亚附近地区之间丰度的区域差异。春季幼虫数量与秋季募集种群数量无明显关系。由于 C. crangon 的寿命短，各种非生物因素和捕食者存在的组合似乎是控制种群大小的主要参数。