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<p>Ages and spawning histories of the anadromous and sexually dimorphic hickory shad (<i>Alosa mediocris</i>) populations were estimated and compared from multiple watersheds along the east coast of the USA to fill life history gaps and provide supplemental information for monitoring and management, specifically for a future baseline stock assessment. Sagittal otoliths from 220 individuals were aged, and corresponding scales were examined for spawning marks from the Roanoke, Cashie, Tar, Pamlico, Neuse, and Cape Fear rivers in North Carolina, and outgroups from the Choptank (Maryland), James (Virginia), Ogeechee (Georgia), and St. Johns (Florida) rivers. Precision of aging estimates was measured between readers and aging structures. Otoliths were found to be more precise than scales. Otolith ages for both sexes ranged from 2 to 7&#xa0;years old and, through model selection, were used to develop both a sex-specific coastwide age-total length relationship and multiple river-specific age-length keys. The number of spawning events for females ranged from 0 to 4 (i.e., a virgin spawner up to 4 previous spawning events), and 0–2 for males. Skip-spawning was a rare occurrence, only observed for seven individuals. Fish from Georgia had the highest mean number of spawning marks (2.00) with Maryland coming in a close second at 1.95. The lowest average (1.25) was from the St. Johns River at the southern end of the species range. These results imply latitudinal differences in iteroparity exist for hickory shad throughout their spawning range. The comprehensive findings in this study support future watershed-specific monitoring and management practices.</p>

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Hickory shad (Alosa mediocris) age and spawning compositions from US East Coast watersheds

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年6月2日

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  • Samantha A. Dowiarz,
  • Roger A. Rulifson

摘要

Ages and spawning histories of the anadromous and sexually dimorphic hickory shad (Alosa mediocris) populations were estimated and compared from multiple watersheds along the east coast of the USA to fill life history gaps and provide supplemental information for monitoring and management, specifically for a future baseline stock assessment. Sagittal otoliths from 220 individuals were aged, and corresponding scales were examined for spawning marks from the Roanoke, Cashie, Tar, Pamlico, Neuse, and Cape Fear rivers in North Carolina, and outgroups from the Choptank (Maryland), James (Virginia), Ogeechee (Georgia), and St. Johns (Florida) rivers. Precision of aging estimates was measured between readers and aging structures. Otoliths were found to be more precise than scales. Otolith ages for both sexes ranged from 2 to 7 years old and, through model selection, were used to develop both a sex-specific coastwide age-total length relationship and multiple river-specific age-length keys. The number of spawning events for females ranged from 0 to 4 (i.e., a virgin spawner up to 4 previous spawning events), and 0–2 for males. Skip-spawning was a rare occurrence, only observed for seven individuals. Fish from Georgia had the highest mean number of spawning marks (2.00) with Maryland coming in a close second at 1.95. The lowest average (1.25) was from the St. Johns River at the southern end of the species range. These results imply latitudinal differences in iteroparity exist for hickory shad throughout their spawning range. The comprehensive findings in this study support future watershed-specific monitoring and management practices.