Reservoir impoundment often alters the hydrological regimes of the river and consequently leads to the extinction of some sensitive species. This study analysed the spawning response of a critically endangered (CR) species, Chinese sturgeon Acipenser sinensis, under the changing hydrological regimes caused by the Three Gorges Reservoir (TGR). Based on our statistic analysis, we inferred that the long duration (>100 days) and large magnitude (>1.8 * 10⁶ m³/s) of high flow pulse in the flood season and low accumulated water temperature in October (<660°C) and November (<540°C) were key hydrological regimes to induce the spawning success of Chinese sturgeon. Such hydrological regimes could not be satisfied after the third phase of the TGR impoundment in 2005, which decreased the suitability of the flow (HSI_F) and temperature (HSI_T) regimes for the spawning of Chinese sturgeon. However, a significant complementary relationship between high HSI_F and low HSI_T was found in all years of successful spawning after 2005, but it did not occur in the nonspawning years of 2013, 2015 and 2017, which could be the reason for spawning failure in these years. In the years 2018 and 2019, although the complementary relationship existed, the spawning failure in these 2 years was probably due to few parent fish. Therefore, we suggest that future conservation measures should focus on both optimizing operations of the TGR to ensure suitable hydrological conditions and restocking with adult fish to ensure successful spawning.

中文翻译：

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长江现有产卵场中华鲟Acipenser sinensis产卵成功的潜在水文制度要求

水库蓄水经常改变河流的水文状况，从而导致一些敏感物种的灭绝。本研究分析了极度濒危 (CR) 物种中华鲟Acipenser sinensis在三峡水库 (TGR) 引起的水文状况变化下的产卵响应。根据我们的统计分析，我们推断持续时间长（>100 天）和大震级（>1.8 * 10 ⁶  m ³/s) 的汛期高流量脉冲和 10 月 (<660°C) 和 11 月 (<540°C) 的低积水温度是诱导中华鲟产卵成功的关键水文情势。在 2005 年三期三峡大坝蓄水后，这种水文状况无法得到满足，这降低了对中华鲟产卵的流量（HSI _F）和温度（HSI _T）状况。然而，高 HSI _F和低 HSI _T之间存在显着的互补关系2005年以后所有产卵成功年份均发现，但2013、2015、2017年非产卵年份均未出现，这可能是这些年份产卵失败的原因。2018年和2019年虽然存在互补关系，但这2年产卵失败很可能是因为亲鱼少。因此，我们建议未来的保护措施应侧重于优化 TGR 的操作以确保合适的水文条件和重新放养成鱼以确保成功产卵。