Abstract Interpreting ecological dynamics is challenging when observed patterns are not aligned with presumed models. Investigating possible sources of uncertainty is critical to understand the underlying system and ultimately inform management decisions. In this study, we used simulation to investigate the hypothesis that observed inconsistencies in Great Lakes lake trout (Salvelinus namaycush) and sea lamprey (Petromyzon marinus) predator-prey dynamics were caused by measurement error in the abundance and predation metrics. When lake trout abundances increase and sea lamprey abundances decrease, predation rates are expected to decline (and vice versa). Occasionally predation rates do not change as expected, leading to an inconsistency in expected predator-prey dynamics. We used a Type II functional response model to align lake trout relative abundance, adult sea lamprey abundance, and sea lamprey marking rates of lake trout in each Great Lake. Then we added measurement error to each of the simulated metrics to see how it contributed to observed inconsistencies in the marking rates. The simulated inconsistency rate was far less than the observed inconsistency rate in Lakes Superior and Erie, indicating that measurement error was not primarily responsible for the misalignment of metrics, contrary to our hypothesis. Rather than ignoring these inconsistencies as unfortunate consequences of imperfect assessments, we recommend that future inconsistencies be scrutinized for possible mechanistic explanations. We suspect that predator-prey dynamics are being influenced by spatially structured within-lake components and the presence of alternative hosts, neither of which were accounted for in the functional response model we used.

中文翻译：

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调查捕食者-猎物动态的明显错位：五大湖湖鳟鱼和海七鳃鳗

摘要 当观察到的模式与假定的模型不一致时，解释生态动力学具有挑战性。调查可能的不确定性来源对于了解底层系统并最终为管理决策提供信息至关重要。在这项研究中，我们使用模拟来调查在大湖湖鳟鱼 (Salvelinus namaycush) 和海七鳃鳗 (Petromyzon marinus) 捕食者-猎物动力学中观察到的不一致是由丰度和捕食指标的测量误差引起的假设。当湖鳟丰度增加而海七鳃鳗丰度减少时，捕食率预计会下降（反之亦然）。有时，捕食率不会按预期改变，导致预期的捕食者-猎物动态不一致。我们使用 II 型功能响应模型来调整每个大湖中湖鳟鱼的相对丰度、成年海七鳃鳗丰度和海七鳃鳗标记率。然后我们将测量误差添加到每个模拟指标中，以查看它如何导致观察到的标记率不一致。模拟的不一致率远低于在苏必利尔湖和伊利湖观察到的不一致率，这表明与我们的假设相反，测量误差不是造成指标错位的主要原因。与其将这些不一致视为不完善评估的不幸后果，我们建议仔细审查未来的不一致以寻找可能的机械解释。