【作者】 王成友；

【导师】 危起伟；

【作者基本信息】 华中农业大学 ， 湿地资源与环境， 2012， 博士

【摘要】 中华鲟(Acipenser sinensis)作为典型的大型溯河生殖洄游型鱼类,是现存鲟形目中唯一跨过北回归线的种类,曾广泛分布于我国近海(包括黄渤海、东海、台湾海峡甚至朝鲜半岛和日本海域)以及流入其中的大型河流(包括长江、珠江、闽江、钱塘江和黄河)。目前,闽江、珠江、钱塘江和黄河种群已经绝迹,长江种群是唯一还有分布的中华鲟种群。1981年葛洲坝水利枢纽工程截流阻断了长江中华鲟的洄游通道,原来分布在葛洲坝以上江段的产前栖息地和产卵场无法再被利用。所幸的是,截流后的第2年发现中华鲟在葛洲坝下至古老背约30km的江段有产卵活动,后期逐渐在葛洲坝至庙咀约3.85km的江段形成较稳定的产卵场,而产卵场面积仅为葛洲坝截流前的5%。但是,2003年三峡水电站开始正式蓄水发电,导致葛洲坝下江段的自然水文节律被打破；2004-2006年在葛洲坝下中华鲟产卵场实施河势调整工程。这些水利工程影响了中华鲟在产卵场的正常分布和产卵活动。此外,由于受生境退化、环境污染、航运以及误捕等诸多因素的影响,加上中华鲟自身的生物学特性,长江中华鲟的资源量在不断下降。尽管针对中华鲟保护采取了包括列为国家一级重点保护动物、全面禁止商业捕捞、建立保护区和实施人工增殖放流等一系列措施,但是仍没有扭转种群下降的趋势。2010年,中华鲟被IUCN红色目录列为极危等级物种(CR)。中华鲟性成熟晚、繁殖周期长,这是恢复种群的不利条件；但是雌性成熟个体的怀卵量大,一定程度上弥补了这种劣势。而这些特点充分说明了保护参加繁殖的中华鲟至关重要。因此,掌握中华鲟进入长江后完整的生殖洄游和栖息地分布状况,确保每一尾中华鲟能够顺利产卵对中华鲟整个种群的保护和恢复意义重大。本文借助超声波遥测和水声学探测并结合微生境测量和地理信息系统等手段,2006-2011年研究了中华鲟进入长江以后完整的生殖洄游过程、中华鲟在葛洲坝下栖息—产卵场的精确分布及其适合度模型(HSI),确定了中华鲟在长江重点江段的产前栖息地分布及非生物环境特征(中生境和微生境尺度),建立了长江重点江段中华鲟的潜在产前栖息地模型,以期为中华鲟产前栖息地保护和人工改良潜在栖息地提供科学依据。具体采用的方法和获得的主要结果如下：1.使用超声波标志并结合移动跟踪和固定监测等手段,观察了27尾中华鲟(8雄、19雌,全长为245-368cm)在长江的洄游过程和分布位置。其中,26尾鱼定位时长范围为7-707d,平均定位859次/尾,另有一尾鱼未获得定位。标志鱼在长江中的完整洄游可分为4种阶段类型：(1)产卵洄游(Spawning migration)。两尾超声波标志中华鲟(1尾雌鱼、1尾雄鱼)分别于6月和10月从海中到达长江口并溯河洄游,其中一尾到达葛洲坝下产卵场(rkm1678),溯河洄游速度分别为0.54km/h(0.26-1.77km/h)和2.20km/h(1.82-2.35km/h),雄鱼的速度大于雌鱼。(2)产前栖息(Pre-spawning holding)。2008年秋季标志的4尾Ⅲ期中华鲟在葛洲坝至庙咀约3.85km的江段长期停留直至第2年的产卵期。(3)产卵迁移(Spawning movements)。所有的标志鱼大部分时间都集中在大江电厂尾水区至庙咀江段洄游,其中,大部分鱼都会在产卵日到来前向下游迁移平均距离约18.21km(3.93-24.64km)后再返回葛洲坝下产卵场。产卵发生时,多数鱼都出现在产卵位点。(4)产后降河洄游(Post-spawning migration)。雌鱼和雄鱼表现出了不同的离开产卵场时间的特征。产卵结束后,雌鱼立即离开,雄鱼则在产卵场停留较长时间再行降河洄游。平均降河速度为4.87km/h (0.68～7.60km/h),并且在不同江段以及性别之间没有显著性差异(P=0.56>0.05和P=0.69>0.05)。此实验获得的结果可为中华鲟在大范围的时空保护策略提供依据。2.获得了25尾中华鲟产卵季节在葛洲坝栖息—产卵场的分布特征。标志鱼在水平空间上呈现高度的聚集分布(Clumped; CE=0.332<1),主要分布于葛洲坝上产卵区(area Ⅰ)、隔流堤左边(东岸；area Ⅰ-Ⅱ)、下产卵区首部(area Ⅲ)、庙咀(area Ⅵ)和十里红江段(area Ⅶ),分布比例占91%。剩余的分布位点位于磨基山(rkm1671)、胭脂坝中部(rkm1665.5)、虎牙滩(rkm1653)。在横向上主要分布于主河槽的深水区位置。分布位置在产卵前后有显著差异(P<0.001),在不同的年际间和不同性别存在差异。性成熟鱼的平均栖息水深为8.71m(95%CI=8.58-8.85m),并且在白天的栖息水深显著大于夜间；通过比较产卵前后15d的栖息水深后发现,随着产卵日的临近,栖息水深逐渐减小,在产卵日达到最小值(平均水深为5.15m)。未达到性成熟的Ⅲ期鱼的平均栖息水深(14.59m；95%CI=13.75-15.43m)大于性成熟鱼(P<0.001)。3.通过超声波遥测数据、野外微生境测量,并基于GIS数据分析平台,绘制出葛洲坝至十里红江段的水深、底部水流、坡度和底部悬移质充塞度的栅格图,并用于分析中华鲟栖息位点的非生物环境。从水深来看,中华鲟栖息位点的平均值为10.10m,大于整个栖息—产卵场的平均水深,栖息水深位置达38.32m。从流速来看,栖息位置的平均流速(1.18m/s；95%CI=1.16-1.19m/s)和底部流速(0.97m/s；95%CI=0.95-0.98m/s)略大于整个栖息地产卵场平均流速(1.14m/s；95%CI=1.12-1.16m/s)和底部流速(0.95m/s；95%CI=0.94-0.96m/s)。栖息位置的推移质充塞度明显大于栖息—产卵场的其他区域。此外,通过比较中华鲟栖息位置与整个栖息—产卵场的值,发现二者水深、平均流速、底部流速和河床坡度上都存在显著性差异(P<0.05)。比较中华鲟栖息位置各因子的相关性发现,中华鲟栖息位置的环境因子之间具有显著的相关性。最后,根据中华鲟栖息位置各变量因子的值,建立了各因子的适合度曲线和综合因子的栖息适合度模型,基于模型算出葛洲坝下适合中华鲟性成熟鱼和未达到性成熟鱼栖息的加权可利用面积(WUA)分别为0.37km2和0.18km2。4.2010-2011年冬季,选择长江重点江段对中华鲟产前分布进行了水声学探测,共获得64个中华鲟信号数据。其中,2010年宜昌至武汉江段(620km)调查期间,总走航里程约为2137.5km,获取中华鲟信号46个；2011年,宜昌至新厂江段(220km)总走航里程约为610km,获取中华鲟信号18个。分析发现,中华鲟主要集中分布在4个江段：葛洲坝下产卵场(5尾)、胭脂坝(5尾)、梅子溪(8尾)和调关(23尾),分布位置与历史文献和本研究组以前的捕捞数据较一致。中华鲟平均鱼体分布水深为17.69m(95%CI=15.84～19.53m),中华鲟分布位置的平均水深为21.63m(95%CI=19.00-24.26m),鱼体位置距河流底部的百分比为85.66%(95%CI=82.09-89.24%),说明中华鲟主要分布于水体的底层。对4个主要分布江段成鱼的栖息水深、栖息位点的水深以及距河底深度进行方差分析或者非参数检验(方差不具齐性的数据),结果显示,葛洲坝栖息—产卵场和胭脂坝中华鲟的鱼体分布水深与其他江段均有差异,而梅子溪和调关中华鲟鱼体分布的水深之间没有显著性差异；葛洲坝栖息—产卵场栖息位置的水深与胭脂坝没有显著差异,但与梅子溪和调关有极显著差异；中华鲟栖息水层在江段之间差异不显著。从总体上看,葛洲坝下栖息—产卵场的中华鲟栖息位点的非生物环境特征与梅子溪和调关差异较大,造成这种差异的主要原因是葛洲坝截流形成了一个非自然状态下栖息地环境。5.通过测量长江重点江段的非生物环境因子,结合回声探测仪获得的中华鲟分布位点数据,建立了中华鲟产前栖息地的关键环境因子适合度曲线,并构建出胭脂坝和调关两个产前栖息地的适合度模型。其次,综合5个自然江段中华鲟产前栖息地的主要地形和水深特征,获得理想状态下中华鲟产前栖息地的适宜特征为：河道为弯曲型或者分叉型,有沙坝或沙洲,河道长度为21.39km,深水区(水深大于19m)长度为13.88km,河道转角为172°,河道平均宽度和深水区宽度为分布874m和279m,深弘线平均水深和最大水深分别为28.01m和40.55m,河道曲折率为2.56。最后基于这些特征筛选出了9个适宜中华鲟产前栖息的江段,其中,4个适宜性较高,5个江段适宜性一般。6.在掌握中华鲟生殖洄游、产前栖息地分布及栖息地适合度的基础上,本文分析和讨论了人类活动尤其是水利工程建设对中华鲟的洄游和栖息地选择产生的影响,并基于这些研究结果,提供了中华鲟就地保护的技术框架,提出了中华鲟的就地保护的努力方向以及一些亟待开展的研究工作,如探索中华鲟洄游机制、完善中华鲟栖息地研究、探寻中华鲟现有栖息地的生境条件、改良中华鲟的潜在产卵场和产前栖息地、评估人类活动对中华鲟种群的影响以及更新中华鲟就地保护和管理建议。更多还原

【Abstract】 Chinese sturgeon (Acipenser sinensis Gray,1835) is a large anadromous sturgeon with the sole sturgeon species crosses the northern temperate zone. Historically, the species ranged widely occurring in the offshore of China (including Yellow Sea, East China Sea, Taiwan Strait, Korean Peninsula and Japan Sea) and the large rivers which flow into these seas (involving Yangtze River, Pearl River, Minjiang River, Qiantangjiang River and Yellow River). Currently, the populations of Minjiang River, Pearl River, Qiantangjiang River and Yellow River have been vanished, the Yangtze River population is the only remaining population of this species. The construction of Gezhouba Dam (GZD) blocked the migratory routes, and the spawning grounds accompanying with pre-spawning holding habitats up the GZD were disappeared in1981. Fortunately, spawning event was found from the GZD to Gulaobei reach with the length of30km in the following year, of which the stable spawning ground was located about3.85km long in the reach from GZD to Miaozui. The scale of spawning ground was only as5%large as the historical. In2003, the impounding of Three Gorges Dam (TGD) changed the natural hydrological rhythm of river reach below the GZD. In2006, the River Adjust Project below in the spawning ground altered the river bedform, which all affected the normal distributions and spawning of adult Chinese sturgeon. In addition, due to the habitat degradation, water pollution, navigation and bycatch, the stock of Chinese sturgeon have been markedly decreasing. This trend has not been reversed although a series of protective measurements were made to protect and restore the population, such as listing it as the first class of protected animals in China, prohibiting fishing, establishing the Nature Reserve and implementing artificial propagation from1983. Finally, the species was classified as Critically Endangered (CR) on the IUCN Red List in2010.The late sexual mature and long reproductive cycle of Chinese sturgeon are adverse to restore the population, but it would be compensated by the large fecundity. Consequently, these features reflect that it is critical to protect each adult. In order to protect and restore the population, it would be important to understand their complete migrations and habitats in the Yangtze River, and ensure the spawning success of each adult Chinese sturgeon. In this paper, the ultrasonic telemetry, echosounder, microhabitat measuring and Geographic Information System was employed to study the migration in the Yangtze River and habitat distributions in the key reach. Secondly, the relationship between the distributions of fish and some critical variables were analyzed, and habitat suitability models were established. Finally, the pre-spawning holding habitats in the key reach were determined and the potential pre-spawning holding habitats were searched based on the models. The results would supply the scientific reference for protecting the pre-spawning holding habitats and spawning ground, and exploring the potential habitats. The main methods and results in this study are as follows:1. From2006to2009, twenty seven ultrasonic-tagged wild adult Chinese sturgeon Acipenser sinensis [8males,19females; total length (LT) range=245～368cm] were captured on the spawning ground just downstream of the GZD in the Yangtze River. Twenty-six individuals were located for7～707days (mean number of relocations=859; range=3～4549). Sturgeon movements were divided into four stage-categories:1) Spawning Migration. Two tagged sturgeons (one female and one male) returned to the Yangtze River and migrated from the Yangtze Estuary (rkm0) to the spawning ground (rkm1678) between June and October. Their mean upstream ground speed was0.54km/h (0.26～1.77km/h) and2.20km/h (1.82～2.35km/h), and the speed of the male was faster than the female.2) Pre-spawning Holding. Four of five females tagged in November2008stayed within rkm1678.00～1674.15for about one year before the spawning period.3) Spawning Movements. All sturgeons swam mostly from the tailrace of the GZD (rkm1678) to the Miaozui (rkm1674.15) reach and some moved downstream about18.21rkm (range=3.93～24.64rkm), but then, returned upstream to the GZD. Most tagged sturgeons were on the spawning ground on the day when the spawning occurred.4) Post-spawning Migration. Males (N=6) and females (N=2) departed the spawning area on a different time schedule, females leaving before males. The mean seaward ground speed of six sturgeons was4.87km/h (range=0.68～7.60 km/h). There were no significant differences in ground speeds among reaches or between sexes (reaches=ANOVA, P=0.56>0.05; sexes=ANOVA, P=0.69>0.05). These broad spatiotemporal scale results will help establish an effective protection strategy for the species in the Yangtze River.2. Twenty-five ultrasonic-tagged wild adult Chinese sturgeons were used to study the distributions on the staging-spawning ground during the spawning seasons. The spatial distribution type of tagged adults was clumped (CE=0.332<1). Most all adult locations (91%) were in the USS, the east section (left side) of the dike, the head (upstream reach) of the DSS, and in the Shilihong reach. The distribution area of MCP was1.67km2, the5rkm from GZD (rkm1678) to Shilihong (rkm1673). Only9%of all locations were at Moji Hill (rkm1671), Yanzhiba Bar (rkm1665.5) and Huyatan (rkm1653). All data indicated that adults selected the main channel for moving upstream or within the spawning grounds. There was significant difference in distributions of fish before and after spawning (P<0.001), and the differences were also found within the different years and between sexes. The mean inhabiting depth of ripe fish was8.71m (95%CI8.58～8.85m), the depth ripe fish used decreased gradually before spawning, and then, swimming depth increased after spawning, with most shallow depths occurring on the spawning day (mean=5.12m). One-way ANOVA analysis showed that there was a significant difference (P<0.001) between sexes for depth use, with females using deeper depths than males. Also, depth use was significantly different between day and night (P<0.001), with adults using deeper water during the day than at night. The mean depth of non-ripe fish was14.59m (95%CI=13.75～15.43m) which was significant deeper than the mean depth of ripe females (ANOVA, P<0.001).3. The raster maps based on depth, bottom velocity, slope, and substrate embeddedness from GZD to Shilihong were established and the variable vaules were extracted from the maps. The mean depth of positions where tagged A. sinensis were located was10.10m and had a significant difference from the entire reach. The lagest value was38.32m. The mean velocity magnitude of inhabiting sites (Mean=1.18m/s,95%CI=1.16～1.19m/s) was larger than the entire reach (Mean=1.14m/s,95%CI=1.12～1.16m/s). The bottom velocity magnitude of locations was0.97m/s (95%CI=0.95～0.98m/s), also larger than the entire reach (Mean=0.95m/s,95%CI=0.94-0.96 m/s). For the topography, the average slope of fish locations was2.15°(95%CI1.96-2.33°) which was smaller than the total reach (mean=3.26°;95%CI=3.12-3.41°). The percentage of bottom sediments of fish locations was significantly larger than the total reach. ANOVA analysis also showed that the mean depth, mean velocity, bottom velocity and channel slope all had significant differences from the entire spawning ground. Pearson correlation analysis showed there was significant relationship between the environment variables. Finally, the suitability curves and habitat suitability index was modelled and the weighted usable areas for ripe and non-ripe fish was0.37km2and0.18km2, respectively.4. During the winter of2010and2011, hydroacoustics was used to detect the pre-spawning sturgeons in the key reach (GZD to Wuhan,620km) and the total of64signals of adult Chinese sturgeons was detected. The paths of2137.5km and610km were detected during2010and2011, correspondingly, the number of46and18individuals was found. The four clumped reaches were identified:the staging-spawning ground below the GZD (5individuals), Yanzhiba Bar (5individuals), Meizixi (8individuals) and Tiaoguan (23individuals), were similar as the historical distributions in the published paper and the results from our team. The mean depth of fish used, water depth of fish locations and the percentage apart from bottom were17.69m (95%CI=15.84～19.53m),21.63m (95%CI=19.00～24.26m) and85.66%(95%CI82.09～89.24%). These indicated that the fish were mostly close to the river bottom mostly. ANOVA analysis and the Non-parameters test was used to study the four reaches, which the results showed as follows:the depth of fish used in the staging-spawning ground below the GZD and Yanzhiba Bar reach was significant difference from the Meizixi and Tiaoguan, but no difference were found between later two reaches; the depth of fish locations was significant difference between each other except the results between the GZD and Yanzhiba Bar; However, there was no significant difference in the water layer of fish. In general, the stock was similar in the staging-spawning ground below the GZD and Yanzhiba Bar, but different from the Meizixi and Tiaoguan reaches.5. Depending on the measurement of aboitc environments and distributions of Chinese sturgeon, the key-factor suitability index curves of pre-spawning holding habitat for Chinese sturgeon were established. Also, the habitat suitability index model were built for the two main pre-spawning holding habitat i.e. Yanzhiba and Tiaoguan. Combined with the parameters of topographic and depth on the five natural reaches, the suitable pre-spawning holding habitat should be as follows:the type of reach was meandering or braided, the reach had sound bar, the length of habitat and deep water zones (>19m) were21.39km and13.88km, respectively. The turning angle of river channel was172°. The river width and the width of deep zones were874m and279m, respectively. The mean depth of thalweg and maximum depth were28.01m and40.55m. the value of S/L was2.56. Finally, nine potential pre-spawning holding habitats were extracted, which were involved four better suitable habitats and five suitable habitats.6. Based on the results of reproductive migrations and distributions of adult Chinese sturgeon in the Yangtze River, this study analyzed and discussed how the human activities, especially, the hydraulic projects, influence the normal migrating and selecting habitats of the adults. This paper provided specific frameworks for the protections and managements. To protect adult Chinese sturgeon in situ, a series of study work need be done in the future, such as studying sturgeon migratory mechanisms, improving the knowledge of sturgeon habitat, understanding the complete requirements of adults in the existing habitat, exploring potential spawning grounds and pre-spawning holding habitats, assessing human activities impact on the population, and updating in situ conserving and managing recommendations.更多还原