中华鲟的性腺发育与退化问题研究

中华鲟(Acipenser sinensis) 是我国的一级重点保护野生动物, 也是长江水生动物保护的旗舰物种。近年来, 中华鲟已多次被监测到未进行野外自然繁殖, 其生存前景堪忧。有关其没有繁殖的原因存在多方面的争议, 尤其是黄真理等提出葛洲坝水利枢纽修建造成中华鲟性腺退化严重, 是导致中华鲟种群数量急剧减少的主要因素; 同时, 还宣称“中科院水生所有关否定中华鲟性腺退化的方法和材料, 是不充分和不可靠的”。为了避免该错误观点对中华鲟的保护造成误导, 文章从中华鲟的性腺发育过程及退化的判断标准、中华鲟的生活史阶段及性腺状态、葛洲坝与三峡工程对中华鲟繁殖影响等方面, 分析该观点的谬误之处。柯福恩等将正常发育的中华鲟III期性腺误判为是“退化性腺”; 文章认为刚进入长江不久的中华鲟亲鱼即出现性腺退化, 不符合中华鲟性腺发育的规律。多年监测数据显示, 葛洲坝水利枢纽导致中华鲟洄游距离缩短并没有改变中华鲟繁殖的时间格局, 也没有改变中华鲟性腺成熟的比例。黄真理等歪曲他人实际监测的数据, 提出的洄游距离影响中华鲟性腺发育的模型纯粹是不懂鱼类生物学的人玩弄的数学游戏。尽管现阶段中华鲟的保护确实遇到了困境, 但随着“长江十年禁渔”的实施, 电捕和滚钩等彻底取缔, 限制产卵场区域人类活动, 加强中华鲟野外产卵场的修复, 并进行更大规格、更大规模的群体放流, 中华鲟的种群还是有可能恢复的。     

Biology and life history of Dabry's sturgeon, Acipenser dabryanus, in the Yangtze River

Dabry's sturgeon, Acipenser dabryanus, is a relatively small (130 cm, 16 kg) and now rare sturgeon restricted to the Yangtze River Basin. It behaves as a resident freshwater fish, does not undertake long distance migrations (except for spawning), and lives in a variety of habitats. It historically spawned in the upper Yangtze River, but the spawning sites are unknown. Acipenser dabryanus reaches maturity earlier than do other Chinese sturgeons, which gives the species aquaculture potential, and artificial spawning has been carried out. However, the native population in the Yangtze has sharply declined in the last two decades due to overfishing, pollution and habitat alteration and destruction, especially since the construction of the Gezhouba Dam, which was built in 1981 across the Yangtze River at Yichang, Hubei Province. Since 1981, Dabry's sturgeon rarely occurs below the Gezhouba Dam because downstream movements are blocked. Clearly, conservation of Dabry's sturgeon must be emphasized. Conservation methods may include protecting habitats, controlling capture and stock replenishment.     

Biology, fisheries, and conservation of sturgeons and paddlefish in China

This paper reviews five of the eight species of acipenseriforms that occur in China, chiefly those of the Amur and Yangtze rivers. Kaluga Huso dauricus and Amur sturgeon Acipenser schrenckii are endemic to the Amur River. Both species still support fisheries, but stocks are declining due to overfishing. Acipenseriformes of the Yangtze River are primarily threatened by hydroelectric dams that block free passage to spawning and feeding areas. The Chinese paddlefish Psephurus gladius now is rare in the Yangtze River system, and its spawning activities were severely limited by completion of the Gezhouba Dam in 1981. Since 1988, only 3–10 adult paddlefishes per year have been found below the dam. Limited spawning still exists above the dam, but when the new Three Gorges Dam is complete, it will further threaten the paddlefish. Artificial propagation appears to be the only hope for preventing extinction of P. gladius, but it has yet to be successfully bred in captivity. Dabry's sturgeon A. dabryanus is a small, exclusively freshwater sturgeon found only in the Yangtze River system. It is concentrated today in reaches of the main stream above Gezhouba Dam. The fishery has been closed since 1983, but populations continue to decline. Acipenser dabryanus has been cultured since the 1970s, and holds promise for commercial aquaculture; availability of aquacultural methods offers hope for enhancing natural populations. The Chinese sturgeon A. sinensis occurs in the Yangtze and Pearl rivers and seas of east Asia. There is still disagreement about the taxonomy of the Pearl and Yangtze River populations. The Yangtze River population is anadromous. Adults begin spawning at about age 14 years (males) and 21 years (females), and adults spend over 15 months in the river for reproduction. Spawning sites of A. sinensis were found every year since 1982 below the Gezhouba Dam, but it seems that insufficient suitable ground is available for spawning. Since 1983, commercial fishing has been prohibited but more measures need to be taken such as establishing protected areas and characterizing critical spawning, summering and wintering habitats.     

中华鲟的保护生物学研究进展

中华鲟是一种洄游性的鲟科鱼类,平时生活于海洋,亲鲟成熟后溯游到江河里繁殖。在长江葛洲坝修筑以前,中华鲟产卵场位于长江上游和金沙江下游江段。６０－７０年代中期,一些科研单位对上游中华鲟繁殖群体及产卵场等进行了较为全面的调查,撰写出现敢《长江鲟鱼类生物学与人工繁殖研究》,中华鲟的人工繁殖也于１９７１年产首获成功。葛洲坝枢纽建成以后,中华鲟繁殖群体被阻隔于葛洲坝下游宜昌江段,围绕大坝对中华鲟生存带来的不     

Variation in the suitability of Chinese sturgeon spawning habitat after construction of dams on the Yangtze River

The Chinese sturgeon (Acipenser sinensis) is an anadromous fish inhabiting the Yangtze River. Migration of Chinese sturgeon from the estuary to upper Yangtze River was blocked by Gezhou Dam, completed in 1981, and a new, much smaller, spawning ground was established below the dam. However, Three Gorges Dam began operating in 2003, altering hydrological conditions in the new spawning grounds and the impact on Chinese sturgeon reproduction was severe. The annual survey of Chinese sturgeon shows that both spawning scale and breeding population decreased during this period. To illustrate the impact of Three Gorges Dam on the spawning grounds and reproduction of Chinese sturgeon, the habitat suitability of spawning grounds on spawning day was simulated using River2D. Results show that the area of suitable spawning grounds positively correlates with the scale of reproduction and both have decreased sharply since 2003.     

长江中华鲟繁殖群体资源现状的初步研究

根据1994—1998年获得的246尾标本,对中华鲟繁殖群体的性比、性腺发育成熟个体比例、年龄结构、体长和体重特征等进行了研究。并结合历史资料,对其种群资源现状进行评价,提出了相应的资源保护措施建议。     

Assessing the effect of Separation Levee Project on Chinese sturgeon (<Emphasis Type="Italic">Acipensor sinensis</Emphasis>) spawning habitat suitability in Yangtze River,China

Chinese sturgeon (Acipenser sinensis) is a protected anadromous fish species. The migration pattern of the fish has been blocked by the construction of Gezhouba Dam, reducing the natural spawning site length to less than 7 km along the Yangtze River. However, the fish has since established an alternative spawning ground in the narrow reach downstream of Gezhouba Dam. To enhance navigation, a Separation Levee Project (SLP) was implemented in the new-found spawning habitat of the fish. To therefore evaluate the effect of the SLP on Chinese sturgeon spawning habitat suitability, the conditions in the spawning habitat were simulated using River2D (a two-dimensional hydrodynamic model). Two main approaches (habitat kinetic energy and circulation metrics) were used in the simulation. The study showed that SLP only slightly changed the physical conditions in the spawning habitat. Using hydrodynamic simulation, the weighted usable area (WUA) before and after the SLP construction was also computed and habitat preference curve developed for water depth and velocity. On the average, SLP reduced WUA—a finding that was consistent with field-measured data. Based on WUA, the habitat conditions were more sensitive to SLP proximity than metrics based on velocity gradients. SLP posed detrimental impacts on the suitability of spawning habitats of Chinese sturgeon. The findings in this study provide further basis for the protection and restoration of Chinese sturgeon spawning habitats in especially the lower reach of Yangtze River.     

中华鲟天然群体蛋白质水平遗传多样性贫乏的初步证据

为阐明我国Ⅰ级珍稀水生保护动物中华鲟天然群体的遗传结构和遗传多样性特征,为其资源的监测量民保护提供科学依据,采用聚丙烯酰胺梯度凝胶电泳技术对中华鲟天然群体进行了蛋白质遗传多态性研究。共研究了１５种蛋白质,有４种蛋白无活呈活性很低,在有活性的１１种蛋白中人测得２６个座位;在２６个座位中,只有１个座位（ＭＤＨ－１）为多态座位。中华鲟多态座位比例（Ｐ）为３．９０％,遗传杂合度（Ｈ）为０．０４,均远远低于     

水生所与三峡和葛洲坝水利工程中的鱼类保护

葛洲坝和三峡水利枢纽是世界上著名的大型水电工程, 对长江中下游防洪、发电、航运、水资源利用等产生了巨大的综合效益。如何减轻葛洲坝-三峡工程对长江流域生态环境及水生生物的影响经历了漫长而激烈的论证过程。中国科学院水生生物研究所(以下简称“水生所”)自始至终参加了这两个工程的水域生态环境影响评价和鱼类保护工作, 并且做出了重要的贡献。在葛洲坝工程的救鱼对象讨论中, 水生所指出救鱼的主要对象是中华鲟; 在救鱼的措施方面, 水生所科学论证了葛洲坝工程不必修建过鱼设施, 中华鲟在葛洲坝下能够自然繁殖, 中华鲟的救护措施以人工繁殖放流和产卵场的保护为主。在葛洲坝工程建设后, 水生所进一步预测了三峡工程对长江珍稀特有鱼类、重要经济鱼类以及渔业的影响, 并且建议在赤水河建立自然保护区, 作为长江上游珍稀特有鱼类的庇护所; 提出最早的生态调度想法, 通过三峡水库的调度形成人造洪峰, 刺激“四大家鱼”产卵等等。实践证明, 水生所做出的工程影响评价和鱼类保护建议是科学的、符合客观实际的, 对国家的决策起到了重要作用。     

VARIATION OF RUNOFF IN THE YICHANG REACH OF YANGTZE RIVER AND ITS INFLUENCE TO THE CHINESE STURGEON SPAWNING UNDER THE CASCADED HYDROPOWER OPERATION北大核心CSCD

Based on the Gini coefficient and Mann-Kendall test, the runoff variation in the Yichang reach of Yangtze River from 1982 to 2017 was evaluated, and its influence to the Chinese sturgeon spawning below the Gezhouba Dam was discussed under the cascaded hydropower operation. The results showed that the runoff and Gini coefficient decreased significantly after the construction of Gezhouba Dam, which synchronously decreased the flow and water levels in spawning days of the Chinese sturgeon. Water temperature had no significant change. The analysis of the abruption revealed great change of hydrological conditions in the spawning days and Gini coefficient in 2004 and 2009, which are coincided with time of the second and fourth phase impoundment of the Three Gorges Reservoir. The correlation analysis indicated that the higher runoff and Gini coefficient would induce Chinese sturgeon to spawn in days with high flow and water levels. These results suggest that the ecological operation of the Three Gorges-Gezhouba cascaded hydropower could enhance the runoff with large inequality and create long duration of high flow pulses during flood seasons. © 2019, Institute of Hydrobiology, Chinese Academy of Sciences. All rights reserved.     

Mitochondrial DNA variation, effective female population size and population history of the endangered Chinese sturgeon, Acipenser sinensis

The anadromous Chinese sturgeon (Acipenser sinensis), mainly endemic to the Yangtze River in China, is an endangered fish species. The natural population has declined since the Gezhouba Dam blocked its migratory route to the spawning grounds in 1981. In the near future, the completion of the Three Gorges Dam, the world's largest hydroelectric project, may further impact this species by altering the water flow of the Yangtze River. Little is currently known about the population genetic structure of the Chinese sturgeon. In this study, DNA sequence data were determined from the control region (D-loop) of the mitochondrial genome of adult sturgeons (n = 106) that were collected between 1995–2000. The molecular data were used to investigate genetic variation, effective female population size and population history of the Chinese sturgeon in the Yangtze River. Our results indicate that the reduction in abundance did not change genetic variation of the Chinese sturgeon, and that the population underwent an expansion in the past. AMOVA analysis indicated that 98.7% of the genetic variability occurred within each year's spawning populations, the year of collection had little influence on the diversity of annual temporary samples. The relative large effective female population size (N _ef) indicates that good potential exists for the recovery of this species in the future. Strikingly, the ratio of N _ef to the census female population size (N _f) is unusually high (0.77–0.93). This may be the result of a current bottleneck in the population of the Chinese sturgeon that is likely caused by human intervention. This revised version was published online in July 2006 with corrections to the Cover Date.     

Assessing the effect of the Three Gorges reservoir impoundment on spawning habitat suitability of Chinese sturgeon (Acipenser sinensis) in Yangtze River,China

The Chinese sturgeon (Acipenser sinensis), a kind of maricolous anadromous migratory fish species, is endangered and protected in China. Historical spawning habitats were distributed in the lower reaches of Jinsha River and the upper reaches of Yangtze River. Since the establishment of the Gezhouba water conservancy pivot in 1981, the migratory route of Chinese sturgeon spawning was blocked. Therefore, the fish was forced to propagate in a new spawning ground which was mainly distributed in the 4-km-long mainstream from Gezhouba Dam to Miaozui in the middle Yangtze River. After water storage and power generation of the Three Gorges reservoir (TGR) in 2003, the propagation of Chinese sturgeon has been impacted gradually. According to field surveys, the fish used to spawn twice a year before TGR impoundment, but only once happened after that. Besides, the spawning scale is also declining with each passing year.In order to simulate and evaluate the effect of TGR impoundment on spawning habitats of Chinese sturgeon, with consideration of their reproductive characteristics, an eco-hydrodynamic model was established by coupling a two-dimensional hydrodynamic model and a fuzzy fish habitat module based on fuzzy logic inference. Flow fields at the studied site in an impoundment scenario and an assumed no impoundment scenario were simulated with the 2D hydrodynamic model. Afterwards, by linking hydrodynamic conditions to the expert knowledge base, the fuzzy habitat model used fuzzy logic inference to compute habitat suitability of the Chinese sturgeon. In addition, the approach was used to propose a suitable instream flow range during the propagation period for Chinese sturgeon. The results indicated that the suitable instream flow needed for Chinese sturgeon spawning in middle Yangtze River should be between 10,000 m³/s and 17,000 m³/s and it also showed that after TGR was put into pilot impoundment operation at the designed water level of 175 m, the habitat suitability has decreased significantly in October. Besides, the water temperature of spawning habitat increased to a higher level in propagation period due to the impoundment of the TGR. All these alterations have had imposed tremendous impacts on the propagation of Chinese sturgeon. Therefore, adjusting impoundment schedule of the TGR to recover the water flow over spawning habitat in October is a crucial way to improve the habitat suitability. Furthermore, the presented method also provides a theoretical basis for further research on the assessment of habitat suitability of aquatic species at a micro-habitat scale.     

Contemporary status of Caspian sturgeon (Acipenseridae) stock and its conservation

The paper describes the contemporary status of sturgeon stocks in the Caspian Sea. The effect of natural reproduction and hatchery production on sturgeon population restocking is estimated. Variations in the status of spawning populations of sturgeons migrating into the Volga River were analysed. Recommendations on appropriate measures for conservation of the Caspian sturgeon stocks are presented.     

Kootenai River velocities,depth, and white sturgeon spawning site selection – a mystery unraveled?

The Kootenai River white sturgeon Acipenser transmontanus population in Idaho, US and British Columbia (BC), Canada became recruitment limited shortly after Libby Dam became fully operational on the Kootenai River, Montana, USA in 1974. In the USA the species was listed under the Endangered Species Act in September of 1994. Kootenai River white sturgeon spawn within an 18‐km reach in Idaho, river kilometer (rkm) 228.0–246.0. Each autumn and spring Kootenai River white sturgeon follow a ‘short two‐step’ migration from the lower river and Kootenay Lake, BC, to staging reaches downstream of Bonners Ferry, Idaho. Initially, augmented spring flows for white sturgeon spawning were thought to be sufficient to recover the population. Spring discharge mitigation enhanced white sturgeon spawning but a series of research investigations determined that the white sturgeon were spawning over unsuitable incubation and rearing habitat (sand) and that survival of eggs and larvae was negligible. It was not known whether post‐Libby Dam management had changed the habitat or if the white sturgeon were not returning to more suitable spawning substrates farther upstream. Fisheries and hydrology researchers made a team effort to determine if the spawning habitat had been changed by Libby Dam operations. Researchers modeled and compared velocities, sediment transport, and bathymetry with post‐Libby Dam white sturgeon egg collection locations. Substrate coring studies confirmed cobbles and gravel substrates in most of the spawning locations but that they were buried under a meter or more of post‐Libby Dam sediment. Analysis suggested that Kootenai River white sturgeon spawn in areas of highest available velocity and depths over a range of flows. Regardless of the discharge, the locations of accelerating velocities and maximum depth do not change and spawning locations remain consistent. Kootenai River white sturgeon are likely spawning in the same locations as pre‐dam, but post‐Libby Dam water management has reduced velocities and shear stress, thus sediment is now covering the cobbles and gravels. Although higher discharges will likely provide more suitable spawning and rearing conditions, this would be socially and politically unacceptable because it would bring the river elevation to or in excess of 537.66 m, which is flood stage. Thus, support should be given to habitat modifications incorporated into a management plan to restore suitable habitat and ensure better survival of eggs and larvae.     

New strategies for brood stock management of sturgeon in the Sea of Azov basin in response to changes in patterns of spawning migration

The sturgeon stock in the Sea of Azov is presently maintained by artificial reproduction allowing for the harvest of sturgeons in this basin. Shortened spawning migrations in regulated rivers and long-term artificial selection of the ripest fish at the hatcheries have resulted in high functional maturity of sturgeon spawners in the sea near the river mouth. The traditional technology of artificial sturgeon reproduction is non-effective under modern ecological conditions. The use of ecological and hormonal methods to control seasonal propagation of stellate sturgeon, A.stellatus , Russian sturgeon, A.gueldenstaedti , beluga, Huso huso , and sterlet, A.ruthenus , make it possible to stagger the sexual cycle of breeders from the various biological groups for early (5 months) or later (6 months) spawning. Use of these methods preserves the natural heterogeneity of sturgeon populations maintained through stocking, and also allows for a considerable increase in the quantity of fry reared at the same production base.
The use of the synthetic analogue of mammalian gonadotropin-releasing hormone (Gn-RHa) is better for inducing maturity of the ripest brood fishes, especially for stellate sturgeon, in comparison with the traditional pituitary injections. The schedule of injections was determined for the various species and seasons of spawning.
Short-term rearing of larvae in ponds (no more than 15 days) and subsequent adaptation to sea water in brackish lagoons (1–5 %o) allows for repeated use of nursery ponds in sturgeon hatcheries and a considerable increase in the quantity and survival of sturgeon juveniles in the sea.
The restoration of the sturgeon population structure in the Sea of Azov is not possible without developing a genetic collection of the fish under a controlled culture regime.     

Using drift nets to capture early life stages and monitor spawning of the Yangtze River Chinese sturgeon (Acipenser sinensis)

A sampling system for capturing sturgeon eggs using a D-shaped bottom anchored drift net was used to capture early life stages (ELS) of Chinese sturgeon, Acipenser sinensis , and monitor annual spawning success at Yichang on the Yangtze River, 1996–2004, before and just after the Three Gorges Dam began operation. Captured were 96 875 ELS (early life stages: eggs, yolk-sac larvae = eleuthero embryos, and larvae); most were eggs and only 2477 were yolk-sac larvae. Most ELS were captured in the main river channel and inside the bend at the Yichang spawning reach. Yolk-sac larvae were captured for a maximum of 3 days after hatching began, indicating quick dispersal downstream. The back-calculated day of egg fertilization over the eight years indicated a maximum spawning window of 23 days (20 October–10 November). Spawning in all years was restricted temporally, occurred mostly at night and during one or two spawning periods, each lasting several days. The brief temporal spawning window may reduce egg predation by opportunistic predators by flooding the river bottom with millions of eggs. During 1996–2002, the percentage of fertilized eggs in an annual 20-egg sample was between 63.5 to 94.1%; however, in 2003 the percentage fertilized was only 23.8%. This sudden decline may be related to the altered environmental conditions at Yichang caused by operation of the Three Gorges Dam. Further studies are needed to monitor spawning and changes in egg fertilization in this threatened population.     

葛洲坝下游江段中华鲟产卵场食卵鱼类资源量估算

为定量评估食卵鱼类对中华鲟资源的危害,1997－2001年间,对中华鲟产卵场所在的葛洲坝水利枢纽坝址至下游庙嘴之间长约5km的江段,进行了渔业捕捞样本抽样和解剖检测,运用体长股分析方法并结合淦获物中不同种类的相对数量比例估算出食卵鱼类资源量,研究结果表明,吞食中华鲟卵的主要有圆口铜鱼,铜鱼,瓦氏黄颡鱼等11种鱼类,其年度资源量为197487－744487尾,多年平均444822尾。     

Using adaptive resolution imaging sonar to investigate Chinese sturgeon (Acipenser sinensis Gray, 1835) behaviour on its only spawning ground in the Yangtze River

The present study investigated the presence of Chinese sturgeon Acipenser sinensis on its only remaining spawning ground (below the Gezhauba Dam), and monitored the behaviour under different environmental conditions from 24 December 2015 to 23 January 2016. A fixed ARIS (Adaptive Resolution Imaging Sonar) system was used and a total of 72 Chinese sturgeon were detected during nine observations. Detections initially recorded a few A. sinensis in the early days of late‐December 2015, with an increase in recordings, leading to a peak in early‐January 2016 and declining thereafter. Water temperature slowly decreased during the study period from 18.1 to 15.7°C. During the middle of this temperature decline the sturgeon observations peaked, suggesting that Chinese sturgeon could have an optimal temperature range. The sturgeon Detections Per Unit Effort (DPUE) was higher in the night hours, peaking before dawn, suggesting a circadian behaviour rhythm. Sturgeon spawning was not observed during the investigation period. A delay in the decrease in water temperature caused by the Three Gorges Reservoir and the few numbers of reproductively mature individuals are suspected to have contributed to the failure in natural breeding.     

Sturgeon abundance and distribution in the Caspian Sea.

The number of sturgeons and their distribution on feeding grounds in the Caspian Sea were assessed. Data were collected between 1991 and 1996 on environmental factors, species composition, and population sizes in the Northern, Middle and Southern Caspian Sea except for Iranian waters. The results show a drastic decline of the sturgeon populations on the feeding grounds at sea. In order to preserve the Caspian Sea sturgeon populations, efforts of all States surrounding the Caspian Sea must be increased and harmonised to serve a single system of fishery management, stock conservation and enhancement measures based on natural reproduction and artificial propagation.     

Dual Annual Spawning Races in Atlantic Sturgeon

Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus, Acipenseridae) populations in the United States were listed as either endangered or threatened under the Endangered Species Act in 2012. Because of the endangered/threatened status, a better understanding of Atlantic sturgeon life-history behavior and habitat use is important for effective management. It has been widely documented that Atlantic sturgeon reproduction occurs from late winter to early summer, varying clinally with latitude. However, recent data show Atlantic sturgeon also spawn later in the year. The group that spawns later in the year seems to be completely separate from the spring spawning run. Recognition of the later spawning season has drastically modified estimates of the population status of Atlantic sturgeon in Virginia. With the combination of new telemetry data and historical documentation we describe a dual spawning strategy that likely occurs in various degrees along most, if not all, of the Atlantic sturgeon''s range. Using new data combined with historical sources, a new spawning strategy emerges which managers and researchers should note when determining the status of Atlantic sturgeon populations and implementing conservation measures.