Non-native rusty crayfish are abundant egg predators on spawning reef habitats for lake trout and coregonines in northern Lake Michigan. To better understand rusty crayfish life-history on these unique habitats, we conducted monitoring in 2012 and 2013 at four locations previously identified as spawning areas for native fish. With the aid of a graphical causal model, we conducted an exploratory statistical analysis using a Bayesian multilevel modeling approach with model selection based on information criteria to identify important environmental variables for predicting rusty crayfish distribution and abundance on spawning reefs. We also compared seasonal trends in relative abundance, inferred from catch-per-unit-effort calculations from trapping, to previously reported accounts from a smaller inland lake. The results from our modeling provide evidence of size-class segregation across subtle changes in habitat characteristics of spawning reefs. Specifically, we found evidence that the distribution of >30 mm rusty crayfish was only weakly related to rock density (#/m²) relative to juveniles and smaller size classes. We also observed highest relative abundances from minnow trap monitoring in mid-October when water temperatures averaged 13.9 °C, which is later in the year and at cooler temperatures than similar monitoring from smaller inland lakes has reported. We hypothesize that unique environmental conditions elicit novel life-history responses from rusty crayfish on Lake Michigan spawning reefs and discuss our findings in the context of native fish restoration in the Laurentian Great Lakes.

非本地生锈的小龙虾是密歇根湖北部湖鳟鱼和鲭鱼产卵珊瑚礁栖息地中丰富的卵食肉动物。为了更好地了解这些独特栖息地的生锈小龙虾的生活史，我们于 2012 年和 2013 年在四个先前被确定为本地鱼类产卵区的地点进行了监测。在图形因果模型的帮助下，我们使用贝叶斯多级建模方法进行了探索性统计分析，模型选择基于信息标准，以确定重要的环境变量，以预测生锈小龙虾在产卵礁上的分布和丰度。我们还比较了相对丰度的季节性趋势，从诱捕的每单位努力计算得出的结论与先前报告的来自较小内陆湖的账户进行了比较。我们建模的结果提供了在产卵礁栖息地特征的细微变化中大小级分离的证据。具体来说，我们发现有证据表明 >30 毫米的生锈小龙虾的分布与岩石密度（#/m² ) 相对于幼鱼和较小的尺寸等级。我们还观察到 10 月中旬小鱼陷阱监测的最高相对丰度，当时水温平均为 13.9 °C，与来自较小内陆湖泊的类似监测报告的类似监测相比，这是在今年晚些时候和更低的温度。我们假设独特的环境条件会引起密歇根湖产卵礁上生锈的小龙虾的新生活史反应，并在劳伦森大湖的本地鱼类恢复的背景下讨论我们的发现。