We examined occupancy and density of larval lampreys (Entosphenus tridentatus and Lampetra spp.) in two rivers in Oregon (USA) restored to a Stage 0 condition 1–5 years prior, using a multiscale occupancy model and a zero-inflated Poisson mixture model. We sampled lampreys using backpack electrofishing in randomly distributed, paired, 1-m² quadrats and recorded environmental data. Probabilities of occupancy and density were higher when water velocity was low, the substrate was noncompacted, and sediment was dominated by fines (<4 mm). At mean water depth (0.34 m) and velocity (0.09 m/s), estimated densities in occupied quadrats were 4.8 lampreys/m² (95%: 3.4–6.9) when the substrate was compacted, and fines were not dominant, and 21.1 lampreys/m² (95%: 17.7–25.3) when the substrate was noncompacted and fines were dominant. Probabilities of detecting occupancy in a 1-m² quadrat sampled by backpack electrofishing were 0.76 (95%: 0.64–0.87) when captured after visual observation and 0.80 (95%: 0.71–0.88) with blind sweeps (i.e., constantly moving the net regardless of observation). The probability of capturing a single lamprey in a quadrat sampled by blind sweeps was 0.32 (95%: 0.27–0.37). Sampling in paired 1-m² quadrats facilitated concurrent examination of patterns in occupancy and density while accounting for capture probability, which could aid temporal monitoring of restored habitats. To the best of our knowledge, this is the first study to document occupancy and estimate densities of larval lampreys in habitats that underwent valley floor restoration to Stage 0. We observed both lamprey genera within 5 years of restoration. Aquatic restoration that increases low-velocity, noncompacted, fine sediment habitats could benefit lampreys.

中文翻译：

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恢复到 0 阶段条件的淡水生境中七鳃鳗幼虫的占有率和密度的空间模式

我们使用多尺度占用模型和零膨胀泊松混合模型，检查了俄勒冈州（美国）两条河流中 1-5 年前恢复到 0 阶段条件的七鳃鳗幼虫（Entosphenus tridentatus和Lampetra spp.）的占用和密度。我们使用背包电捕鱼法在随机分布、成对的 1-m ²样方中对七鳃鳗进行了采样，并记录了环境数据。当水流速度较低、基质不压实且沉积物以细粉（<4 毫米）为主时，占据概率和密度较高。在平均水深 (0.34 m) 和流速 (0.09 m/s) 下，当基质被压实时，占用样方的估计密度为 4.8 七鳃鳗/m ² (95%: 3.4–6.9)，细粉不占主导地位，21.1当基质未压实且细粉占主导地位时，七鳃鳗/m ^{2 (95%: 17.7–25.3)。}目视观察后捕获的背包电捕鱼采样的1 米²样方中检测到占用的概率为 0.76（95%：0.64–0.87），盲扫（即不断移动渔网）为 0.80（95%：0.71–0.88）与观察无关）。通过盲扫采样的样方中捕获单个七鳃鳗的概率为 0.32（95%：0.27-0.37）。成对 1-m ²样方采样有助于同时检查占用率和密度模式，同时考虑捕获概率，这有助于对恢复的栖息地进行时间监测。据我们所知，这是第一项记录谷底恢复至第 0 阶段的栖息地中七鳃鳗幼虫数量和密度的研究。我们在恢复后的 5 年内观察到了这两个七鳃鳗属。增加低速、非压实、细沉积物栖息地的水生恢复可能有利于七鳃鳗。