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<p>Growth, maturity, and mortality of invasive Sacramento pikeminnow (<i>Ptychocheilus grandis</i>) in Northern California’s South Fork Eel River were studied to provide sex-specific life history information for this species. We obtained scale samples (<i>n</i> = 297) and gonad samples (<i>n</i> = 57) over 4&#xa0;years (2018, 2019, 2022, and 2023) from fish suppression efforts that used spearfishing, electrofishing, gillnetting, seining, trapping, and angling. We modeled age-length relations using the von Bertalanffy growth equation, yielding different parameters for females (<i>L</i><sub><i>∞</i></sub> = 598.0&#xa0;mm standard length, <i>k</i> = 0.23&#xa0;year<sup>−1</sup>, and <i>t</i><sub><i>0</i></sub> =  − 0.09&#xa0;year) and males (<i>L</i><sub><i>∞</i></sub> = 339.8&#xa0;mm, <i>k</i> = 0.49&#xa0;year<sup>−1</sup>, and <i>t</i><sub><i>0</i></sub> =  − 0.03&#xa0;year). Based on logistic regression, we found that females mature at larger sizes and older ages than males, with 50% of females estimated to mature at 355.6&#xa0;mm and 4.0&#xa0;years compared to 211.8&#xa0;mm and 1.8&#xa0;years for males. We estimated total and sex-specific annual mortality rates using the Chapman–Robson method, averaging 54% for all fish, 60% for males, and 45% for females. Sacramento pikeminnow exhibited a very large degree of sexual size dimorphism, with an average standard length of 259&#xa0;mm for mature males and 440&#xa0;mm for mature females, representing the first documentation of sexual dimorphism for this species in the literature. A small, post hoc comparison of otolith- and scale-based ages (<i>n</i> = 12 fish) indicated general agreement through age 5, but one fish suggested scale ages could be biased low; future work should involve a formal age validation for this species. Improving understanding of Sacramento pikeminnow life history will aid ongoing modeling and management efforts aimed at controlling the non-native population in the Eel River basin which is hindering the recovery of several native species that are threatened or endangered.</p>

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Growth, maturity, and mortality of Sacramento pikeminnow (Ptychocheilus grandis) in the South Fork Eel River, California

  • 期刊论文

  • 发表日期：

    2025年8月8日

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  • Alexander W. Juan,
  • Darren M. Ward,
  • Rafael Cuevas-Uribe,
  • Andre Buchheister

摘要

Growth, maturity, and mortality of invasive Sacramento pikeminnow (Ptychocheilus grandis) in Northern California’s South Fork Eel River were studied to provide sex-specific life history information for this species. We obtained scale samples (n = 297) and gonad samples (n = 57) over 4 years (2018, 2019, 2022, and 2023) from fish suppression efforts that used spearfishing, electrofishing, gillnetting, seining, trapping, and angling. We modeled age-length relations using the von Bertalanffy growth equation, yielding different parameters for females (L∞ = 598.0 mm standard length, k = 0.23 year−1, and t0 =  − 0.09 year) and males (L∞ = 339.8 mm, k = 0.49 year−1, and t0 =  − 0.03 year). Based on logistic regression, we found that females mature at larger sizes and older ages than males, with 50% of females estimated to mature at 355.6 mm and 4.0 years compared to 211.8 mm and 1.8 years for males. We estimated total and sex-specific annual mortality rates using the Chapman–Robson method, averaging 54% for all fish, 60% for males, and 45% for females. Sacramento pikeminnow exhibited a very large degree of sexual size dimorphism, with an average standard length of 259 mm for mature males and 440 mm for mature females, representing the first documentation of sexual dimorphism for this species in the literature. A small, post hoc comparison of otolith- and scale-based ages (n = 12 fish) indicated general agreement through age 5, but one fish suggested scale ages could be biased low; future work should involve a formal age validation for this species. Improving understanding of Sacramento pikeminnow life history will aid ongoing modeling and management efforts aimed at controlling the non-native population in the Eel River basin which is hindering the recovery of several native species that are threatened or endangered.