We aimed to determine the spawning period of black sea bream Acanthopagrus schlegelii in Hiroshima Bay, Japan, based on the distribution of its eggs, to assist in the resource management of this species. We developed a monoclonal antibody assay for the identification of black sea bream eggs, and appraised its specificity using immunohistochemical staining and DNA barcoding. To estimate the black sea bream spawning season in 2015 and 2016 in the major fishing ground of Hiroshima Bay, we collected 4061 eggs, attributed to pelagic black sea bream using our assay, and calculated the gonadosomatic index of 715 black sea bream adults to confirm the correspondence between egg presence and spawning season. We estimated that the spawning season of this species extended from mid-April until early July in both 2015 and 2016, and that it peaked in early May, about 20 days earlier than the peak reported for this species in the early 1980s. This temporal shift may be related to increasing seawater temperatures in Hiroshima Bay associated with climate change and ocean warming.

中文翻译：

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从卵密度的时间变化估计日本广岛湾黑鲷 Acanthopagrus schlegelii 的产卵季节

我们旨在根据卵分布确定日本广岛湾黑鲷 Acanthopagrus schlegelii 的产卵期，以协助该物种的资源管理。我们开发了一种用于鉴定黑鲷卵的单克隆抗体检测方法，并使用免疫组织化学染色和 DNA 条形码评估其特异性。为了估计广岛湾主要渔场 2015 年和 2016 年黑鲷产卵季节，我们收集了 4061 颗卵，使用我们的测定归为远洋黑鲷，并计算了 715 只黑鲷成鱼的性腺指数，以确认卵存在与产卵季节之间的对应关系。我们估计该物种的产卵期在 2015 年和 2016 年都从 4 月中旬延长到 7 月初，并在 5 月初达到顶峰，比 1980 年代初该物种报告的峰值早了大约 20 天。这种时间变化可能与气候变化和海洋变暖相关的广岛湾海水温度升高有关。