Kirczuk Lucyna, Dziewulska Katarzyna, Czerniejewski Przemysław, Brysiewicz Adam, Rechulicz Jacek, Ligięza Janusz
Department of Hydrobiology, Institute of Biology, University of Szczecin, Felczaka 3c Street, Szczecin, 71-412, Poland.
Molecular Biology and Biotechnology Center, University of Szczecin, Wąska 13 Street, Szczecin, Szczecin, 71-415, Poland.
Sci Rep. 2025 Jul 8;15(1):24507. doi: 10.1038/s41598-025-10597-8.
The brown bullhead is a fish native to North America that became an invasive species after being introduced into the waters of Europe and other regions. Studies on its sexual cycle and fecundity were conducted on a population from an oxbow lake of the central Vistula River in Poland. The fish ranged in age from 1 + to 9+. The average body length (SL) was 14.4 ± 3.4 cm. Individuals as young as 1 + were already mature. Females lay eggs multiple times from mid-April to mid-June, with absolute fecundity averaging 3227 oocytes and relative fecundity at 46 oocytes g. The highest mean GSI of 1.9 during spawning was recorded in June. The reproductive tract of males takes the shape of lobes and consists of a paired cranial region formed by testes and a caudal region of undefined function. In males, semi-cystic spermatogenesis occurs, with secondary spermatocytes leaving cysts. Males overwinter with tubules filled with spermatids and initiate spermatozoa formation. The highest average GSI of 0.49 was recorded in early April. The brown bullhead observed in the new habitat was characterized by multiple egg laying, earlier maturation of individuals, and spawning in the earlier part of the calendar year, i.e. mid-April to mid-June, compared to its native habitat.
褐牛头鮰是一种原产于北美的鱼类，在被引入欧洲和其他地区的水域后成为了入侵物种。对来自波兰维斯瓦河中游一个牛轭湖种群的褐牛头鮰的性周期和繁殖力进行了研究。这些鱼的年龄从1+到9+不等。平均体长（标准长度）为14.4±3.4厘米。年仅1+的个体就已成熟。雌性在4月中旬至6月中旬多次产卵，绝对繁殖力平均为3227个卵母细胞，相对繁殖力为46个卵母细胞/克。6月记录到产卵期间最高平均性腺指数为1.9。雄性的生殖道呈叶状，由由睾丸形成的成对头部区域和功能不明的尾部区域组成。在雄性中，发生半囊状精子发生，次级精母细胞离开囊肿。雄性在充满精子细胞的小管中越冬，并开始形成精子。4月初记录到最高平均性腺指数为0.49。与原生栖息地相比，在新栖息地观察到的褐牛头鮰具有多次产卵、个体早熟以及在日历年度较早时期（即4月中旬至6月中旬）产卵的特点。
