A key process affecting variation in the recruitment of fish into fisheries is the spatiotemporal overlap between prey and predator (match−mismatch hypothesis, MMH). The Northeast Arctic cod Gadus morhua and its dominant prey, the copepod Calanus finmarchicus, have long been studied in the Norwegian−Barents Sea system. However, the mechanistic explanation of how cod survival is affected by MMH dynamics remains unclear. Most MMH studies have focused on either the time synchrony or the spatial overlap between trophic levels. Here, we used G. morhua larvae and C. finmarchicus data collected in the Norwegian−Barents Sea via ichthyoplankton surveys from 1959−1992 to assess the effect of the predator−prey relationship on predator recruitment to the fisheries at age 3 (as a measure of survival) and to develop a metric of predator− prey overlap using spatio-temporal statistical models. We then compared the inter annual variability of the predator– prey overlap with the predator’s abundance at recruitment to assess how MMH dynamics explain the survival of cod during its early life stages. We found that the amount of overlap be tween cod larvae (length: 11−15 mm) and their prey explained 29% of cod recruitment variability. Positive correlations be tween predator−prey overlap and subsequent recruitment were also found for predators of 6−10 and 16−20 mm, but not for 21+ mm. This improved predator−prey overlap metric is thus (1) useful to better understand how predator−prey dynamics at early life stages of fish impact the survival of later stages; and (2) a valuable tool for assessing the state of an ecosystem.

中文翻译：

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挪威-巴伦支海系统中的匹配失配动态

影响渔业招募鱼类变化的一个关键过程是猎物和捕食者之间的时空重叠（匹配-不匹配假设，MMH）。长期以来，挪威-巴伦支海系统一直在研究北极东北部鳕鱼 Gadus morhua 及其主要猎物桡足类 Calanus finmarchicus。然而，关于鳕鱼存活如何受 MMH 动力学影响的机制解释仍不清楚。大多数 MMH 研究都集中在时间同步或营养级之间的空间重叠上。在这里，我们使用了 G. morhua 幼虫和 C. finmarchicus 数据通过 1959 年至 1992 年间的浮游鱼调查在挪威 - 巴伦支海收集，以评估捕食者 - 猎物关系对捕食者在 3 岁时向渔业招募的影响（作为生存的衡量标准）并制定捕食者的度量标准-猎物重叠使用时空统计模型。然后，我们比较了捕食者 - 猎物重叠的年度变化与捕食者在招募时的丰度，以评估 MMH 动力学如何解释鳕鱼在其早期生命阶段的存活。我们发现，鳕鱼幼虫（长度：11-15 毫米）与其猎物之间的重叠量解释了 29% 的鳕鱼募集变异性。对于 6-10 和 16-20 毫米的捕食者，捕食者-猎物重叠和随后的招募之间也发现了正相关，但对于 21+ 毫米的捕食者则没有。因此，这种改进的捕食者-猎物重叠度量有助于 (1) 有助于更好地了解鱼类早期生命阶段的捕食者-猎物动态如何影响后期的生存；(2) 评估生态系统状态的宝贵工具。