Bigheaded carp (Bighead Carp Hypophthalmichthys nobilis and Silver Carp H. molitrix) are invasive species in the USA and have spread throughout much of the Mississippi River basin. Population abundance upstream of Lock and Dam (LD) 19 (LD19) on the upper Mississippi River (UMR) has likely been limited by the high-head dam at this location, which restricts all upstream fish passage to the lock chamber. We measured otolith (lapillus) stable isotope composition and elemental microchemistry of 146 Silver Carp (n = 77 females, 69 males) and 141 Bighead Carp (n = 76 females, 65 males) to determine early life environments (ELEs) of adult bigheaded carp captured upstream of LD19 at the invasion front, in an area of intense management (Pools 16–19). Otolith oxygen isotope ratios (δ¹⁸O) and elemental ratios (Sr:Ca and Ba:Ca) were compared to values of isotope and elemental ratios in water from putative ELEs to assign the ELE for each fish. Most Bighead Carp (68.8%) and Silver Carp (54.1%) collected upstream of LD19 had otolith core signatures consistent with ELEs downstream of LD19. Nineteen percent of Bighead Carp and 34% of Silver Carp could not be classified. The sex ratios of bigheaded carp (Pools 17–19 combined) with otolith core signatures downstream of LD19 did not differ from 1:1. Our results, when compared to those of Whitledge et al. (2019), suggest low but stable recruitment above this population pinch-point dam in the UMR and suggest that targeting removal of bigheaded carp downstream of LD19 or inhibiting their movement upstream through the lock there might be effective as part of integrated control efforts.

中文翻译：

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使用耳石化学确定密西西比河上游 16-19 池中新兴鳙鱼种群的早期生活环境和运动

鳙鱼（鳙鱼Hypophthalmichthys nobilis和鲢鱼H. molitrix）是美国的入侵物种，已遍布密西西比河流域的大部分地区。密西西比河上游 (UMR) 闸坝 (LD) 19 (LD19) 上游的人口丰度可能受到该位置高水头大坝的限制，这限制了所有上游鱼类进入闸室的通道。我们测量了 146 条鲢鱼（n  = 77 条雌性，69 条雄性）和 141 条鳙鱼（n = 76 名女性，65 名男性）以确定在入侵前沿的 LD19 上游捕获的成年鳙鱼的早期生活环境（ELE），在密集管理区域（池 16-19）。耳石氧同位素比值 (δ ¹⁸O) 和元素比率（Sr:Ca 和 Ba:Ca）与来自假定 ELE 的水中同位素和元素比率值进行比较，以分配每条鱼的 ELE。在 LD19 上游收集的大多数鳙鱼 (68.8%) 和鲢鱼 (54.1%) 的耳石核心特征与 LD19 下游的 ELEs 一致。19%的鳙鱼和34%的鲢鱼无法归类。具有 LD19 下游耳石核心特征的鳙鱼（池 17-19 合并）的性别比例与 1:1 没有差异。与 Whitledge 等人的结果相比，我们的结果。(2019)，建议在 UMR 的这个种群夹点大坝上方进行低但稳定的招募，并建议以清除 LD19 下游的鳙鱼为目标或抑制它们通过那里的水闸向上游移动可能​​是有效的，作为综合控制工作的一部分。