Abstract Sea lampreys attack fish, killing some and leaving marks on others. Great Lakes fishery managers rely on observed marking rates to assess the success of the sea lamprey control program and estimate sea lamprey-induced mortality of lake trout. Because marking rates are only observed on survivors of sea lamprey attacks, they may not provide a reliable index of actual attack or mortality rates. To investigate the effect of survivor bias, we developed a simulation model representing a single season (June–December) of sea lamprey attacks. Simulated attack rates varied with month and lake trout size; simulated pierce and lethality rates varied with month alone. Surveyed marking rates were represented by simulated survivors in October; true rates were calculated from all simulated lake trout (dead and alive) in December. Simulation results were subsetted to include only those within the range of marking rates actually observed in the Great Lakes. Type A (piercing) marking rates were a good index of the sea lamprey attack rate and the sea lamprey-induced mortality rate if annual lethality rates were relatively constant. Type B (non-piercing) marking rates were a good index of the sea lamprey attack rate and the sea lamprey-induced mortality rate if annual pierce rates were relatively constant. Due to the uncertainty surrounding the pierce and lethality rates, we recommend that sea lamprey abundance information be incorporated in existing lake trout statistical catch-at-age models via a functional response component relating sea lamprey feeding to lake trout abundance, if possible.

中文翻译：

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使用模拟了解湖鳟的年度海七鳃鳗标记率

摘要 海七鳃鳗攻击鱼类，杀死一些鱼并在另一些鱼身上留下痕迹。五大湖渔业管理人员依靠观察到的标记率来评估海七鳃鳗控制计划的成功，并估计海七鳃鳗引起的湖鳟死亡率。因为标记率仅在海七鳃鳗袭击的幸存者身上观察到，它们可能无法提供实际袭击或死亡率的可靠指数。为了研究幸存者偏差的影响，我们开发了一个模拟模型，代表了海七鳃鳗袭击的单个季节（6 月至 12 月）。模拟攻击率随月份和湖鳟大小而变化；模拟刺穿率和致死率仅随月份而变化。调查的评分率以 10 月份的模拟幸存者为代表；真实率是根据 12 月所有模拟湖鳟鱼（死的和活的）计算得出的。模拟结果被细分为仅包括在五大湖中实际观察到的标记率范围内的结果。如果年致死率相对恒定，A 型（刺穿）标记率是海七鳃鳗攻击率和海七鳃鳗诱导死亡率的良好指标。如果年度刺穿率相对恒定，B 型（非刺穿）标记率是海七鳃鳗攻击率和海七鳃鳗诱导死亡率的良好指标。由于穿孔率和致死率的不确定性，我们建议在可能的情况下，通过将海七鳃鳗喂养与湖鳟鱼丰度相关联的功能响应组件，将海七鳃鳗丰度信息纳入现有的湖鳟统计捕捞年龄模型中。