Jenkins Laura E, Medeiros Lea R, Graham Neil D, Hoffman Brian M, Cervantes Diana L, Hatch Douglas R, Nagler James J, Pierce Andrew L
Department of Biological Sciences and Center for Reproductive Biology, University of Idaho, 875 Perimeter Dr., Moscow, ID 83844, USA.
Columbia River Inter-Tribal Fish Commission, 700 NE Multnomah St, Suite 1200, Portland, OR 97232, USA.
Gen Comp Endocrinol. 2023 Feb 1;332:114181. doi: 10.1016/j.ygcen.2022.114181. Epub 2022 Nov 28.
Consecutive and skip repeat spawning (1- or ≥2-year spawning interval) life histories commonly occur in seasonally breeding iteroparous fishes. Spawning interval variation is driven by energetic status and impacts fisheries management. In salmonids, energetic status (either absolute level of energy reserves or the rate of change of energy reserves, i.e., energy balance) is thought to determine reproductive trajectory during a critical period ∼1 year prior to initial spawning. However, information on repeat spawners is lacking. To examine the timing and the aspects of energetic status that regulate repeat spawning interval, female steelhead trout (Oncorhynchus mykiss) were fasted for 10 weeks after spawning and then fed ad libitum and compared to ad libitum fed controls. Plasma growth hormone (GH) and insulin-like growth factor-I (IGF-I) levels were measured to assess long-term energy balance. Plasma estradiol levels showed that some fish in both groups initiated a consecutive spawning cycle. In fasted fish, GH was lower at spawning in consecutive versus skip spawners. In consecutive spawners, GH was higher at spawning in fed versus fasted fish. These results suggest that fish with a less negative energy balance at spawning initiated reproductive development in the absence of feeding, but that feeding during the post-spawning period enabled initiation of reproduction in some fish with a more negative energy balance at spawning. Thus, both energy balance at spawning and feeding after spawning regulated reproductive schedules. These results show that the critical period model of salmonid maturation applies to regulation of repeat spawning, and that the reproductive decision window extends into the first 10 weeks after spawning.
连续和间隔重复产卵（产卵间隔为1年或≥2年）的生活史常见于季节性繁殖的多次繁殖鱼类中。产卵间隔的变化受能量状态驱动，并影响渔业管理。在鲑科鱼类中，能量状态（即能量储备的绝对水平或能量储备的变化率，也就是能量平衡）被认为在初次产卵前约1年的关键时期决定繁殖轨迹。然而，关于重复产卵者的信息却很缺乏。为了研究调节重复产卵间隔的能量状态的时间和方面，对雌性虹鳟（Oncorhynchus mykiss）在产卵后禁食10周，然后随意喂食，并与随意喂食的对照组进行比较。测量血浆生长激素（GH）和胰岛素样生长因子-I（IGF-I）水平以评估长期能量平衡。血浆雌二醇水平表明两组中的一些鱼都开始了连续的产卵周期。在禁食的鱼中，连续产卵者在产卵时的GH水平低于间隔产卵者。在连续产卵者中，喂食的鱼在产卵时的GH水平高于禁食的鱼。这些结果表明，产卵时能量平衡负值较小的鱼在不进食的情况下开始了生殖发育，但产卵后进食使一些产卵时能量平衡负值较大的鱼能够开始繁殖。因此，产卵时的能量平衡和产卵后的进食都调节了繁殖时间表。这些结果表明，鲑科鱼类成熟的关键时期模型适用于重复产卵的调节，并且生殖决策窗口延伸到产卵后的前10周。
