The reproductive success of marine ectotherms is especially vulnerable in warming oceans due to alterations in adult physiology, as well as embryonic and larval survival prospects. These vital responses may, however, differ considerably across the species' geographical distribution. Here we investigated the life history, focusing on reproductive ecology, of three spatially distant populations (stocks) of Atlantic cod (Gadus morhua, Gadidae) (50–80° N), in the Irish/Celtic Seas-English Channel Complex, North and Barents Seas, under past and projected climate. First, experimental tracking of spawning behaviour evidenced that the ovulation cycle is highly distressed at ≥9.6 (±0.25)°C (T_up). This knife-edge threshold resulted in erratic spawning frequencies, whereas vitellogenin sequestration remained unaffected, indicating endocrine rather than aerobic scope constraints. Cod in the Celtic Sea-English Channel are, therefore, expected to show critical stock depensation over the next decades as spawning grounds warm above T_up, with Irish Sea cod subsequently at risk. Second, in the relatively cooler North Sea, the northward retraction of Calanus finmarchicus (Calanidae) and Para-Pseudocalanus spp. (Clausocalanidae) (1958–2017) limit cod larvae feeding opportunities, particularly in the southernmost subarea. However, the contrasting increase in Calanus helgolandicus (Calanidae) does not counteract this negative effect, likely because cod larvae hatch ahead of its abundance peaks. Overfishing again comes as a twin effect. Third, in the still relatively cold Barents Sea, the sustainably harvested cod benefit from improved food conditions in the recent ice-free polar region but at the energetic cost of lengthier and faster spawning migrations. Consequently, under climate change local stocks are stressed by different mechanistic factors of varying management severity.

中文翻译：

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在持续的气候变化下，纬度不同的大西洋鳕鱼种群面临着根本不同的生物物理挑战

由于成年生理学以及胚胎和幼虫生存前景的改变，海洋变温动物的繁殖成功在变暖的海洋中尤其脆弱。然而，这些重要的反应可能因物种的地理分布而有很大差异。在这里，我们调查了爱尔兰/凯尔特海-英吉利海峡综合体、北部和北部大西洋鳕鱼（ Gadus morhua ，鳕鱼科）（北纬 50–80 °）的三个空间遥远的种群（种群）的生活史，重点是生殖生态学。过去和预测气候下的巴伦支海。首先，产卵行为的实验跟踪证明排卵周期在≥9.6 (±0.25)°C ( T _up). 这个刀刃阈值导致产卵频率不稳定，而卵黄蛋白原螯合不受影响，表明内分泌而不是有氧范围限制。因此，预计凯尔特海-英吉利海峡的鳕鱼在未来几十年内将出现严重的种群减少，因为产卵场温度高于T_上升，随后爱尔兰海鳕鱼将面临风险。其次，在相对凉爽的北海， Calanus finmarchicus（Calanidae）和Para-Pseudocalanus spp向北退缩。（Clausocalanidae）（1958-2017）限制了鳕鱼幼虫的摄食机会，特别是在最南端的分区。然而，与此相反的是Calanus helgolandicus的增加（Calanidae）不会抵消这种负面影响，可能是因为鳕鱼幼虫在其丰度峰值之前孵化。过度捕捞再次带来双重影响。第三，在仍然相对寒冷的巴伦支海，可持续捕捞的鳕鱼得益于近期无冰极地地区食物条件的改善，但代价是产卵迁徙时间更长、速度更快。因此，在气候变化下，当地种群受到不同管理强度的不同机制因素的压力。