Fecundity is a necessary metric to assess reproductive potential (e.g., spawning potential ratio and recruitment overfishing) in invasive fishes, yet the direct measurement of fecundity is often difficult, impractical, and time consuming. Therefore, the ability to estimate fecundity from field measurements (i.e., TL, relative weight [W_r], or ovary weight) can be a valuable tool for fisheries managers to estimate reproductive potential. The goal of this study was to relate the batch fecundity of invasive Silver Carp Hypophthalmichthys molitrix and Bighead Carp H. nobilis to metrics that can be quickly measured to eliminate the need for direct enumeration. Silver and Bighead carp were collected from the upper Mississippi River (UMR) in the summer of 2016 and 2017. Subsamples of mature (spawning capable) ovaries were preserved, enumerated, and then related to ovary weight, TL, weight, and W_r. An equation for estimating Silver Carp batch fecundity from ovary weight in the UMR, corrected for ovary membrane weight, was developed: {ovary weight – [0.222 × (ovary weight^0.7589)]} × 794 (SE = 11). Batch fecundity for Silver Carp from Pools 17–20 of the UMR averaged 1,230,930 ± 68,983 eggs (mean ± SE). Ovary weight was the strongest predictor of fecundity, but TL, weight, and W_r also showed significant relationships with fecundity for Silver Carp. Batch fecundity for Bighead Carp averaged 1,043,953 ± 82,360 eggs, but the number of eggs per gram showed significant spatial variation; therefore, no fecundity equation was developed for this species. Future work should evaluate the frequency of Silver Carp spawns within a season and how batch fecundity varies among multiple spawning events. Fecundity estimates can be used to determine spawning potential ratios, which can help in evaluating management strategies.

中文翻译：

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一种估算鳙鱼批次繁殖力的快速方法

繁殖力是评估入侵鱼类繁殖潜力（例如，产卵潜力比率和补充过度捕捞）的必要指标，但直接测量繁殖力通常很困难、不切实际且耗时。因此，通过实地测量（即 TL、相对重量 [ W _r ] 或卵巢重量）估计繁殖力的能力可以成为渔业管理者估计繁殖潜力的宝贵工具。本研究的目的是将入侵的鲢鱼Hypophthalmichthys molitrix和鳙鱼的批次繁殖力相关联。紫菜到可以快速测量的指标，以消除直接枚举的需要。2016 年和 2017 年夏季从密西西比河上游 (UMR) 采集鲢鱼和鳙鱼。对成熟（可产卵）卵巢的子样本进行保存、计数，然后与卵巢重量、TL、重量和 W r相关_联。开发了根据 UMR 中的卵巢重量估算鲢鱼批次繁殖力的方程式，针对卵巢膜重量进行了校正：{卵巢重量 – [0.222 × (卵巢重量 0.7589 )]} × 794 (SE = 11 ⁾。UMR 第 17-20 池鲢的批次繁殖力平均为 1,230,930 ± 68,983 个卵（平均值 ± SE）。卵巢重量是繁殖力的最强预测因子，但 TL、重量和W _r也显示出与鲢鱼繁殖力的显着关系。鳙鱼的批次平均产卵量为 1,043,953 ± 82,360 粒，但每克产卵数显示出显着的空间差异；因此，没有为这个物种制定生育力方程。未来的工作应该评估一个季节内鲢鱼的产卵频率，以及批次繁殖力在多个产卵事件中的变化情况。繁殖力估计可用于确定产卵潜在比率，这有助于评估管理策略。