固化河岸对长江江豚栖息活动的影响

长江江豚主要栖居在近岸浅水水域,喜好泥沙质类型的河岸。但在长江干流,有很多自然河岸被固化,河岸固化给长江江豚分布和栖息活动造的影响仍不甚清楚。2016年3月—2017年1月,对长江干流2个自然河段江豚的数量和分布做了12次考察,并收集了这2个河段岸型的相关数据,来分析固化河岸对江豚栖息活动的影响。12次考察累计发现江豚215头次,平均每次考察观察到江豚(17.92±7.09)头次。研究区域的固化河岸约占岸线总长的59%,分析发现,仅约13.9%的江豚分布在固化河岸水域,86.1%的江豚均分布在自然河岸水域。江豚在单位河岸长度的分布数量与该段固化河岸长度所占的比例呈显著负相关(r=-0.639,P0.01)。在自然河岸,分布在近岸50 m水域的江豚占31.8%,而在固化河岸,仅观察到2头江豚活动在近岸50 m水域内。由此可见,固化河岸对江豚的近岸分布有明显影响。调查还发现,安庆城区建设带约10 km江段12次考察均未发现江豚分布,城区建设带可能对江豚栖息已造成严重影响。长江干流的固化河岸所占比例非常高,研究结果提示这可能导致长江干流江豚栖息地的丧失和破碎化加剧,在制定长江江豚保护措施必需慎重考虑此因素的影响,并据此提出相应的栖息地保护和恢复方案。     

北部湾印太江豚密度估算及适宜栖息地预测

目前我国印太江豚 (Neophocaena phocaenoides) 的基础信息十分有限,2018—2020年对北部湾离岸较近的广西壮族自治区合浦儒艮国家级自然保护区及离岸较远的涠洲岛水域进行了截线抽样法船只考察。应用DISTANCE估算出儒艮国家级自然保护区印太江豚密度约为每平方千米0.273 (0.133 ~ 0.561) 头,数量约88头 (95%CI：43 ~ 181);涠洲岛水域印太江豚密度约为每平方千米0.100 (0.048 ~ 0.210) 头,数量约137头 (95%CI：65 ~ 286)。利用最大熵模型 (MaxEnt) 分析北部湾水域印太江豚的适宜栖息地分布及面积。MaxEnt模型训练集和测试集AUC值分别为0.980和0.927,模型拟合度较好,结果表明离岸距离和海洋深度是影响印太江豚栖息地分布的主要因子,印太江豚的适宜栖息地在北部湾东北部近岸区和海南西侧,适宜度超过0.5的栖息地面积达14 630.62 km²。2018—2020年印太江豚适宜栖息地面积较2013年大幅度下降,0.5适宜度的栖息地面积减少了40%。参考印太江豚2个群体的平均密度和北部湾适宜栖息地面积,粗略估计北部湾水域印太江豚约1 463 ~ 3 994头。由此可见,北部湾水域内印太江豚密度比较高,应引起足够的重视。建议首先进行区域性海洋环境的整体保护,重点关注鱼类资源的恢复及对人类活动尤其渔船的管控,并尽快建立新的自然保护区。     

江西水域枯水期长江江豚种群数量和分布特征

研究于2021年11—12月,设置12条考察路线,采用同步目视考察法,对包含长江干流江西段、鄱阳湖和赣江下游的江西水域长江江豚数量和分布开展了考察,结合历史资料,探讨了该水域长江江豚种群数量和分布规律及江湖迁徙关系。结果显示, 11月考察观测到长江江豚217群次、454头次, 12月考察观测到长江江豚236群次、569头次,受水位和天气等环境条件影响,两次考查观察到的长江江豚数量差异显著(t=–2.23, P<0.05)。11月和12月江豚分布规律基本一致:长江江西段,江豚主要分布在湖口石钟山-彭泽三号洲水域;鄱阳湖适宜水深范围水域都有长江江豚分布,其中吴城望湖亭-渚溪河口、都昌船厂-黄金咀-三山-瓢山水域是江豚高密度分布区;赣江下游,长江江豚分布在扬子洲渔业村附近水域。两次考察目击率分别为1.00和1.08次/km,均高于往年调查结果,由此推测,鄱阳湖长江江豚种群数量可能有所增长。鄱阳湖通江水道蛤蟆石-石钟山水域,两次考察分别仅发现3头和2头长江江豚,推测调查期间长江江豚在长江干流和鄱阳湖之间的迁移行为较少,未来需进一步管控江湖迁移水域的人类活动,促进江湖迁移。吴城望湖亭-渚溪...     

长岛海域东亚江豚种群密度和分布的初步研究

长岛海域是黄渤海东亚江豚(Neophocaena asiaeorientalis sunameri)的热点分布区域之一。为了掌握长岛海域东亚江豚的种群密度与分布特征，2019年10月至2021年10月采用截线抽样法进行了5次东亚江豚目视考察。5次考察总航程2 421 km，共发现东亚江豚614次，1 156头次。相同月份调查种群遇见率无显著性差异(P> 0.05)，不同月份种群遇见率差异极显著(P <0.01)，提示东亚江豚种群在该水域可能存在季节性迁移。按照考察月份对数据进行合并处理，长岛海域5月和10月东亚江豚平均种群密度为(0.56±0.11)头/km²(0.46～0.68头/km²)和(3.63±0.25)头/km²(3.38～3.88头/km²)，平均种群数量为(20 209±202)头和(2 971±681)头，这在目前已知所有东亚江豚分布区中是最高的。尽管不同季节种群数量差异显著，但东亚江豚种群在长岛海域的空间分布特征相似，砣矶岛-大钦岛西北侧和东南侧均为高密度分布区，因此...     

不同流态中长江江豚的栖息活动比较

长江江豚(Neophocaena asiaeorientalis)呈斑块状分布在长江干流,对栖息地有明确的选择性.流态是栖息地水文环境的核心内容.为研究长江江豚对不同流态的选择性,本文根据1993-2021年对长江下游15次样线考察记录到的412次,合计1 117头江豚个体的栖息活动进行了统计分析.结果表明:全年长江江...     

长江河口区江豚种群调查

为弄清长江河口区江豚(Neophocaena asiaeorientalis)种群数量和分布情况,于2012年6月8~11日和2012年9月12~19日对这一水域作了2次较大覆盖面的目视考察和9次遗骸搜寻。6月的考察目击到江豚5群8头,9月的考察未目击江豚个体。依据样带法估算,长江河口水域6月份的江豚种群数量约为61头。全年共获得7头江豚遗骸,并搜集到其他5例死亡信息。对其中5头外表完整、特征保留良好的遗骸所作的鉴定结果显示,2头为长江亚种(N.asiaeorientalis asiaeorientalis),3头为东亚亚种(N.asiaeorientalis sunameri)。调查表明,崇明岛西端和青草沙附近水域是长江亚种活动的热点水域,可作为重点监护区域。     

渤海江豚种群现状初探

渤海是黄渤海江豚种群的重要分布区,但是有关该区域江豚的种群数量的资料极其匮乏。2015年至2016年,采用截线抽样法在渤海水域开展了6个航次的目视调查,收集了渤海江豚的分布数据,首次评估了区域内的江豚种群数量,为制定有效的渤海江豚种群生态保护策略提供了基础资料。调查结果显示,在2015年8月、2016年5~7月、9月和11月进行的6个调查航次共计8972 km的有效航程中,发现江豚87次、136头次。江豚在渤海各海湾和中部水域都可观察到;14:00-18:00时段、离岸15~35km范围内较易观察到江豚;黄河口外、秦皇岛东北侧老龙口和莱州外沿岸河口水域,江豚出现频次较多。各季节中,以5月在黄河口外20~40km范围内发现江豚的频次和数量最多。采用Distance 7.0软件估算渤海江豚种群数量,其中探测概率分别取值0.399、0.85和1时,渤海江豚种群数量估算值分别为7883头（CV=0.21）、3701头（CV=0.21）和3124头（CV=0.21）,对应的种群密度分别为1.441头/km2、0.066头/km²和0.056头/km²,均低于已报道的南黄海和日本海江豚种群相应值。受海上天气、调查条件和经验所限,本文估值可能存在偏差,但限于渤海江豚历史资料缺乏的现状,本文的结果对于认识渤海江豚的种群状况仍具有重要参考意义。     

鄱阳湖及其支流长江江豚种群数量及分布

在1997 年11 月至1998 年11 月的134 d 中, 大致按一年四季, 分4 次对鄱阳湖及其主要支流中的长江江豚种群数量、数量的季节变动、分布、行为、江豚栖息地环境、人类活动对江豚的影响进行了考察。江豚的分布主要集中在鄱阳湖湖区, 赣江、信江、抚河等主要支流的中下游和支流入湖的湖口附近。冬、春、秋3 个季节鄱阳湖水系长江江豚种群数量的估计值分别为91 头、431 头和260头。即, 鄱阳湖江豚的种群数量约为100～400 头,其种群数量随季节、水位、鱼类资源的变化而呈现出相应的变化。     

野化放归丹顶鹤活动节律、家域特征和栖息地选择

了解野放丹顶鹤的运动模式、家域和栖息地选择的时间节律特征对丹顶鹤种群保护和栖息地管理尤为重要。基于GPS-GSM跟踪数据,综合运用3S技术、动态布朗桥模型、栖息地选择指数,研究了盐城海滨湿地野放丹顶鹤在不同生活周期的活动节律、家域的面积和重叠指数,以及栖息地选择。结果表明：(1)丹顶鹤日活动节律具有明显的周期性特征。丹顶鹤活动强度：育成期>越冬期>孵化期>育雏期,孵化期和育雏期日间活动强度平稳,育成期和越冬期呈“双峰”模式。(2)丹顶鹤95%家域面积均值介于(111.18±22.15)hm²—(621.28±105.77)hm²,育成期((621.28±105.77) hm²)>育雏期((226.83±54.86) hm²)>孵化期((112.40±7.72) hm²)>越冬期((111.18±22.15) hm²);核心家域面积均值介于(0.53±0.26)—(45.78±6.66) hm²,育成...     

长江东流河道整治对长江江豚种群数量的影响

长江江豚是生活在长江中下游的濒危水生哺乳动物,通常活动在江心洲和浅水缓滩附近。航道整治改变了鱼类栖息活动的水文环境,也给豚类生存带来负面影响。本文根据长江东流河道整治施工前和施工后各3 次野外考察资料,分析了3 种流态中江豚的数量与群结构。结果表明,该工程实施前江豚主要栖息活动在边滩的分离区,其次在洲头的分流区。工程实施后,整治江段的江豚种群数量年下降率达8. 9% 。江豚在分流区活动已消失,在分离区集群规模较小,且在流态之间移动增大。本文研究结果也提示长江江豚就地保护难度越来越大,从长江干流中把长江江豚迁入故道中是一件刻不容缓的工作。     

Mitochondrial control region variability of baiji and the Yangtze finless porpoises,two sympatric small cetaceans in the Yangtze river

BaijiLipotes vexillifer (Miller, 1918) and the Yangtze finless porpoiseNeophocaena phocaenoides asiaeorientalis (Pilleri and Gihr, 1972) are two sympatric small cetaceans inhabiting the middle and lower reaches of the Yangtze River. In this study, a fragment (420–428 bp) of the mitochondrial control region was sequenced to provide the first comparative survey of genetic variability and population structure in these two endangered species, with samples of finless porpoises from the Yellow/Bohai Sea, East China Sea, and South China Sea also included. Low values of haplotype diversity and nucleotide diversity were found for both species, especially for the baiji and the Yangtze River and South China Sea populations of finless porpoises. The analysis of molecular variance (AMOVA) supported a high level of overall genetic structure among three porpoise populations in Chinese waters, with greatest differences found between either the Yangtze River population or the Yellow Sea population and the South China Sea population. The differentiation between the Yangtze and Yellow Sea populations was not significant, and the males have higher genetic differentiation than the females, suggesting a significant female-biased dispersal between these two populations. This study showed that the Yangtze finless porpoise, unlike the sympatric baiji, was not a genetically isolated population. The Yangtze and Yellow Sea porpoises should be included in the same management unit, but further studies using more samples and especially based on more molecular markers are urgently needed to confirm this.     

The Diel Rhythms of Biosonar Behavior in the Yangtze Finless Porpoise (Neophocaena asiaeorientalis asiaeorientalis) in the Port of the Yangtze River: The Correlation between Prey Availability and Boat Traffic

Information on the habitat use of the critically endangered Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) is critical for its conservation. The diel biosonar behavior of the porpoise in the port areas of the Yangtze River was examined along with simultaneous observations of fish density and boat traffic. Biosonar pulses from the porpoises were detected for 1233 min (5.77%) over a 21,380 min duration of effective observations. In total, 190 (5.63%) buzzes (an indication of prey capture attempts) were recorded among the 3372 identified click trains. Of the 168 echolocation encounters (bouts of click trains less than eight min apart), 150 (89.3%) involved single animals, indicating that solitary porpoises were frequently present and feeding in the port areas. Significant diel patterns were evident involving the biosonar behavior of the porpoises (including click trains and buzzes), fish density and boat traffic. The frequencies of the click trains and buzzes were significantly lower during the day than in the evening and at night, which suggests that porpoises in this region are primarily engaged in crepuscular and nocturnal foraging. The lack of a significant diel pattern in the echolocation encounters indicates the importance of the port in porpoise conservation. A forced feeding schedule may be associated with the lack of a significant correlation between porpoise acoustics and boat traffic. Overall, prey availability appears to be the primary factor that attracts porpoises. Additionally, porpoises tend to migrate or remain downstream in the morning and migrate or remain upstream in the evening, most likely to follow their prey. The findings of this study can be used to improve the conservation of the Yangtze finless porpoise.     

长江湖口至荻港段江豚春季对生境选择的初步分析

研究表明鲸类的分布领域、集群规模、索食场所及迁移途径与栖息环境的地貌特征及生境因子密切相关（Watts and Gaskin,1986;Baumgartner,1997;Raum-Suryan et a1．,1998;Karczmarski et a1．,2000）。距离苏格兰较远的Moray Firth海域,生活的一群瓶鼻海豚（Tursiops truncatuz）,它们常聚集在岛屿附近的狭窄深槽入口处,那儿海床呈斜坡,     

Detection of Helicobacter in the fecal material of the endangered Yangtze finless porpoise Neophocaena phocaenoides asiaeorientalis

In animals, infection by the Epsilonproteobacteria Helicobacter spp. and H. cetorum is widespread. It has been suggested that H. cetorum may cause gastritis in cetaceans. The aim of our study was to investigate the presence of Helicobacter spp. in the fecal material of the endangered Yangtze finless porpoise Neophocaena phocaenoides asiaeorientalis. The fecal material of 12 porpoises living in the wild in Poyang Lake and 1 porpoise living in captivity at the Wuhan Baiji Dolphinarium were examined by PCR for the presence of Helicobacter spp. The fecal material of 8 of 12 wild porpoises and the captive porpoise were positive for Helicobacter spp. as determined by PCR using Helicobacter-specific primers, which target the 16S rRNA gene. A 16S rRNA clone library was then prepared from 1 sample isolated from a female porpoise living in the wild. DNA sequence analysis from 3 of the clones showed 98 to 99% identity to the H. cetorum 16S rRNA gene. These results demonstrate the prevalence of Helicobacter spp. and H. cetorum in endangered freshwater finless porpoises.     

Seasonal changes in the local distribution of Yangtze finless porpoises related to fish presence

The Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) is an endangered freshwater porpoise subspecies unique to the Yangtze River basin. Seasonal variations in local distribution of the animal, as well as fish presence, sand dredging, ship navigation, and bridges were examined as potential factors affecting the occurrence of the animals. Passive acoustic surveys were performed regularly from May 2007 to August 2010, near the conjunction of the Yangtze River and Poyang Lake. The distribution of the porpoises was seasonally site‐specific. In May and August, the animals were detected more often at river junctions than in the lake, but vice versa from November to February. The rate of the porpoise detection was significantly higher in areas of fish presence than in areas of absence. The number of porpoises detected did not differ significantly between the sand dredging operation and the prohibition period (in 2008), although the number of vessels obviously declined in 2008. Ship traffic and bridges also did not appear to affect the presence of porpoises. These results showed the relative importance of the various environmental factors, which is important for conservation of not only Yangtze finless porpoise but also endangered isolated cetaceans.     

Yangtze finless porpoises along the main channel of Poyang Lake,China: Implications for conservation

Poyang Lake is the largest freshwater lake in China and flows into the Yangtze River. It is a traditional habitat for the endangered Yangtze finless porpoise, which has not been well investigated. To reveal the distribution of the porpoise in Poyang Lake, 12 passive acoustic surveys were conducted along 123 km of the main channel of the lake during different seasons (spring transition season, wet season, autumn transition season, and dry season) from 2008 to 2012. We counted the number of phonating porpoises encountered and calculated the detection rate (encountered individuals detected per kilometer). The median porpoise detection rates ranged from 0 to 0.65 individuals per kilometer during the different surveys. The highest median detection rate of 0.50 was detected in the autumn transition season. The seasonal shrinking of the lake during the dry season may cause a concentration of porpoises in the narrow channels and a high incidence of collisions with cargo ships and fishing boats. Conservation actions should be focused on the main channel of the lake during the dry and transition seasons. In addition, the expansion of the existing reserve to include areas with high porpoise detection rates is necessary.     

Auditory temporal resolution and evoked responses to pulsed sounds for the Yangtze finless porpoises (<Emphasis Type="Italic">Neophocaena phocaenoides asiaeorientalis</Emphasis>)

Temporal cues are important for some forms of auditory processing, such as echolocation. Among odontocetes (toothed whales, dolphins, and porpoises), it has been suggested that porpoises may have temporal processing abilities which differ from other odontocetes because of their relatively narrow auditory filters and longer duration echolocation signals. This study examined auditory temporal resolution in two Yangtze finless porpoises (Neophocaena phocaenoides asiaeorientalis) using auditory evoked potentials (AEPs) to measure: (a) rate following responses and modulation rate transfer function for 100 kHz centered pulse sounds and (b) hearing thresholds and response amplitudes generated by individual pulses of different durations. The animals followed pulses well at modulation rates up to 1,250 Hz, after which response amplitudes declined until extinguished beyond 2,500 Hz. The subjects had significantly better hearing thresholds for longer, narrower-band pulses similar to porpoise echolocation signals compared to brief, broadband sounds resembling dolphin clicks. Results indicate that the Yangtze finless porpoise follows individual acoustic signals at rates similar to other odontocetes tested. Relatively good sensitivity for longer duration, narrow-band signals suggests that finless porpoise hearing is well suited to detect their unique echolocation signals.