Serum concentrations of gonadotropins and steroid hormones of Neophocaena phocaenoides asiaeorientalis in middle and lower regions of the Yangtze River

As a relatively isolated and unique freshwater population, the Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis) is the most endangered subpopulation of this species. The objective of this study was to improve our understanding of their reproductive endocrinology by measuring (radioimmunoassay) serum concentrations of FSH, LH, estradiol (E(2)), progesterone (P(4)) and testosterone (T(2)) in free-ranging animals. Blood samples were collected from 66 Yangtze finless porpoises (41 males and 25 females) captured in the middle and lower reaches of the Yangtze River. Based on significant variation of serum T(2) concentrations in males with body length (BL) >138 cm, we inferred that they were mature; in these animals, there were significant seasonal variations in serum T(2) concentrations, with the highest concentrations in March and April (502.0+/-319.8 ng/dL, mean+/-S.D.) and the lowest in December (79.4+/-83.2 ng/dL). Serum T(2) concentrations positively correlated with serum concentrations of LH and weakly correlated with serum concentrations of E(2), whereas there was a significant negative correlation between serum LH and FSH concentrations in males >138 cm. The smallest apparently pregnant female porpoise had a BL of 130 cm. Serum P(4) concentrations ranged from 13.2 to 112.4 ng/mL (43.9+/-28.3 ng/mL) in pregnant females, and fluctuated under 1.0 ng/mL in non-pregnant females with BL>130 cm. Serum LH concentrations were significantly higher in non-pregnant females >130 cm versus those females <130 cm. To our knowledge, this is the first study of endocrine-related maturity and seasonal breeding characteristics of the Yangtze finless porpoise.     

Do Porpoises Choose Their Associates? A New Method for Analyzing Social Relationships among Cetaceans

Background

Observing and monitoring the underwater social interactions of cetaceans is challenging. Therefore, previous cetacean studies have monitored these interactions by surface observations. However, because cetaceans spend most of their time underwater, it is important that their underwater behavior is also continuously monitored to better understand their social relationships and social structure. The finless porpoise is small and has no dorsal fin. It is difficult to observe this species in the wild, and little is known of its sociality.

Methodology/Principal Findings

The swim depths of 6 free-ranging finless porpoises were simultaneously recorded using a time-synchronized bio-logging system. Synchronous diving was used as an index of association. Two pairs, #27 (an immature female estimated to be 3.5 years old) and #32 (an adult male), #28 (a juvenile male estimated to be 2 years old) and #29 (an adult male), tended to participate in long periods of synchronized diving more frequently than 13 other possible pairs, indicating that the 4 porpoises chose their social partners. The adult males (#32, #29) tended to follow the immature female (#27) and juvenile male (#28), respectively. However, during synchronized diving, the role of an initiator often changed within the pair, and their body movements appeared to be non-agonistic, e.g., rubbing of bodies against one another instead of that on one-side, as observed with chasing and escaping behaviors.

Conclusions/Significance

The present study employed a time-synchronized bio-logging method to observe the social relationships of free-ranging aquatic animals based on swimming depth. The results suggest that certain individuals form associations even if they are not a mother and calf pair. Long synchronized dives occurred when particular members were reunited, and this suggests that the synchronized dives were not a by-product of opportunistic aggregation.     

Post-mortem investigations on stranded dolphins and porpoises from Hong Kong waters

Stranded cetaceans reported from the territorial waters of Hong Kong during the period May 1993 to March 1998 were examined to establish factors that may have contributed to their death. During the current study, 28 Indo-Pacific hump-backed dolphins (Sousa chinensis), 32 finless porpoises (Neophocaena phocaenoides), and four bottlenose dolphins (Tursiops truncatus) were necropsied. Bacteria (15 species) were isolated from nine animals. Of these bacteria, 47% were of possible fecal origin reflecting the high level of sewage contamination in Hong Kong's waters. One finless porpoise displayed wounds caused by a shark attack, and two female finless porpoises presented prolapsed uteri. At least 10 finless porpoises showed evidence of moderate to heavy lungworm infections (Halocercus pingi), and this appears to have been a factor contributing to death in at least six animals. Evidence suggesting blunt traumatic injury (probably caused by boat collisions) was found in six cetaceans (three finless porpoises and three hump-backed dolphins). Signs of fishery-related mortality were detected in at least nine animals (six hump-backed dolphins, two finless porpoises, and one bottlenose dolphin). Of these two human-caused mortality types, pre-existing disease or bacterial infection were detected in 29% of cases. Results indicate that human factors may have played a significant role in the death of at least 15 animals (32% of hump-backed dolphins, 15% of finless porpoises, and 25% of bottlenose dolphins).     

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,     

Variations in independent areas of activity of captive Yangtze finless porpoises, <Emphasis Type="Italic">Neophocaena phocaenoides asiaeorientalis</Emphasis>, during the acclimation period after wild capture

The acclimation process of Yangtze finless porpoises to a limited holding pool after their introduction to this new captive environment is presented. One male (#1) and two female (#2, #3) finless porpoises, newly captured from two different sections of China’s Yangtze River, were observed in an indoor holding pool with an area of 155 m² from January 1997 to January 1998 (animal #3 was removed from the pool in mid-February 1997). Three separate areas in the pool were predefined. Time spent in each of the areas was individually monitored two or three sessions a week using the focal sampling method. In total, 71.3 h of observations (316 sessions) were recorded, with an average observation time each month of about 2.4 h (10 sessions) for each porpoise. The percentage of time spent in each area per month was calculated for each porpoise, and the variations in the percentage of time spent in each area was compared. Results indicated that independent areas of activity existed among porpoises during the early stages of captivity. However, over time, the frequent approaches of the female to the male caused these areas to fade away, resulting in almost equal use of the entire pool area by the newly formed group. The existence of the independent areas of activity during the early months of captivity indicates that newly introduced individuals from different wild subgroups may need separate areas for activities. However, further studies with more animals are needed to draw more general conclusions about the individual areas of activity of this subspecies when in captivity.     

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.     

长江江豚对人工投食适应过程的观察

作者于1989,1992,2001 和2003 年,从长江铜陵江段共捕获24 头长江江豚,在长江干流水域中,用不同的围养方式做摄食行为的观察,累计88 d。结果表明,野外捕获的长江江豚对人工投喂有3 种适应行为:(1)拒食行为;(2)警戒行为;(3)摄食行为。长江江豚的平均拒食天数为2.4 d,其中成年江豚拒食达3 d,而未成年江豚仅拒食1.5 d,两者差异极为显著(P < 0.01)。在冬季和春季圈养试验中,长江江豚的日食量随时间呈上升趋势,冬春季差异显著(P <0.01)。第2 周后江豚警戒行为所用时间不足3 min,但持续时间较长。根据冬季观察,7 周后长江江豚在40 min 内所摄取的食量不足体重的7% ,推测其摄食行为仍处在适应调整阶段。     

Contextual impacts on individual and synchronous breathing rate variations in three captive odontocete groups

Breathing rates are often collected both in the wild and in captivity to inform on cetaceans' internal state. However, few studies have investigated the effect of various factors on this breathing rate. We investigated the variations of individual and synchronous breathing rates depending on individual features (species, sex, age), displayed behavior, social parameters (social grouping), and environmental parameters (diurnal variation, presence of enrichment, unusual events, and presence of visitors in three groups of captive odontocetes (Yangtze finless porpoises, Neophocaena asiaeorentalis asiaeorientalis, East‐Asian finless porpoises, Neophocaena asiaeorentalis sunameri, bottlenose dolphins, Tursiops truncatus). Both individual and synchronous breathing rates were the highest when animals engaged in energetic or social behaviors. Individual breathing rate decreased but synchronous breathing rate increased with the presence of enrichment. Both rates increased during unusual events (e.g., pool cleaning, presence of a diver in the pool, noise, transport) and when public was present for Yangtze finless porpoises. Finally, synchronous breathing rate increased for Yangtze finless porpoises when experiencing social separation. We suggest that individual and synchronous breathing rates are useful parameters to measure, both in wild and captive animals, to obtain information on their arousal/stress state. However, these rates should be interpreted with caution and should be used together with other parameters to allow more accurate inferences.     

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。     

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。     

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.     

Biosonar behaviour of free-ranging porpoises

Detecting objects in their paths is a fundamental perceptional function of moving organisms. Potential risks and rewards, such as prey, predators, conspecifics or non-biological obstacles, must be detected so that an animal can modify its behaviour accordingly. However, to date few studies have considered how animals in the wild focus their attention. Dolphins and porpoises are known to actively use sonar or echolocation. A newly developed miniature data logger attached to a porpoise allows for individual recording of acoustical search efforts and inspection distance based on echolocation. In this study, we analysed the biosonar behaviour of eight free-ranging finless porpoises (Neophocaena phocaenoides) and demonstrated that these animals inspect the area ahead of them before swimming silently into it. The porpoises inspected distances up to 77 m, whereas their swimming distance without using sonar was less than 20 m. The inspection distance was long enough to ensure a wide safety margin before facing real risks or rewards. Once a potential prey item was detected, porpoises adjusted their inspection distance from the remote target throughout their approach.     

Diurnal changes of behavior and respiration of Yangtze finless porpoises (Neophocaena phocaenoides asiaeorientalis) in captivity

A preliminary study was carried out to investigate diurnal changes of behavior of three, one adult male, one adult female, and one juvenile female, Yangtze finless porpoises (Neophocaena phocaenoides asiaeorientalis) in captivity. The respiration and behavior of the porpoises were recorded for 222 hr across 42 days. Behavioral data were recorded for eight general categories: aerial display and fast swimming, begging for fish, playing, nonsexual socializing, sexual behavior, resting, rubbing, and miscellaneous (i.e., other behaviors not included in the above categories). Each behavioral category was scored using one‐zero sampling with 10‐min intervals. The adult male showed shorter mean respiratory intervals at night (19:00–7:00 h), whereas the mean respiratory intervals of the females were shorter during the day (7:00–19:00 h). Begging for fish of all individuals, playing of the juvenile female, nonsexual socializing, and miscellaneous behavior of the adult female and resting of the male were observed more easily in the day, and aerial display and fast swimming of the adults and resting of the females were observed more easily at night. No significant diurnal difference was found, however, in the remaining categories of each individual. Each of the three porpoises therefore showed a distinct diurnal pattern, but none was obviously more active in the daytime than during the nighttime. Results suggest that daytime‐only feeding schedules may be insufficient to meet the energetic needs of marine mammals that show a 24‐hr activity cycle, and that nighttime feeding may be a worthwhile addition to husbandry routines. Zoo Biol 0:1–11, 2005. © 2005 Wiley‐Liss, Inc.     

长江江豚野外健康状况的调查

对铜陵江段捕获的7头长江江豚（Neophocaena phocaenoides asiaeorientalis)进行了体征与血液学分析。结果表明,健康的个体有2头,2头个体有明显的病变,余者营养不良,患不同程度的贫血症。这可能与长江渔业资源日趋枯竭有关。     

Living with dolphins: Local ecological knowledge and perceptions of small cetaceans along the Sindhudurg coastline of Maharashtra,India

Two near shore small cetaceans occur commonly along the Maharashtra coast, the Indian Ocean humpback dolphin and Indo Pacific finless porpoise. These cetaceans frequently interact with fisheries in this region due to overlap in space and resource use. Besides stranding records, little ecological information is available about these species from Maharashtra. We conducted 143 semistructured interviews to document local ecological knowledge and community perceptions of small cetaceans in 30 coastal fishing villages in Sindhudurg. Perceptions of finless porpoises were largely neutral, whereas humpback dolphins were negative. A classification regression tree (CART) analysis (root node error: 60%) showed that the annual cost of gear damage was an important predictor variable of humpback dolphin perceptions, followed by occupation (gear type) and age. Entanglements were reported for both species in large and small gill nets, and shore seines. Perceived net damage and catch loss due to humpback dolphins was six times greater than that of finless porpoises. However, finless porpoises were reportedly more frequently entangled in gear than humpback dolphins. We provide an insight into the perceptions of cetaceans in the local community and the fisheries‐cetacean interactions that shape them.     

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。     

Respiratory pattern of captive Yangtze finless porpoises (Neophocaena phocaenoides asiaeorientalis)

Cetacean respiration usually happen in bouts. The most widely applied quantitative method used to analyze the structure of these bouts is the log_e-survivorship analysis, based on the assumption that the respiratory intervals are distributed as negative exponentials. However, for the data collected from three captive Yangtze finless porpoises (Neophocaena phocaenoides asiaeorientalis), we failed to obtain a convergent result with the application of log_e-survivorship analysis. However, the two-Gaussian model, which was recently proposed to analyze the feeding behavior of cows, was successfully fitted to the data. According to the fitting results, the overall respiratory pattern of the captive Yangtze finless porpoises can be described as a dive with a mean duration of around 30–40 s, followed by two or three ventilations with a mean interval of approximately 9 s. The average intra-bout intervals during both active and inactive periods are constant at 7.7–9.9 s for all individuals. However, when shifting from active to inactive states, the adult male and female decrease their mean numbers of respirations per bout and average length of inter-bout respiratory intervals, while the estimates of both parameters increase for the juvenile female. It was pointed out that the two-Gaussian model might be more adequate for cetacean respiratory-bout structure analyses than the log_e-survivorship technique.     

长江江豚的无线电跟踪研究

采用无线电跟踪技术对生活在长江故道中的江豚进行了跟踪,较好地解决了无背鳍豚类的无线电信标的无损伤固定和淡水环境中信标的自动脱落两个技术关键。跟踪结果理想。     

湖北天鹅洲故道试养江豚生活习性的初步观察

为抢救濒危水生兽类白暨豚,建立保护区无疑是最有效的途径,１９９０年３月到１９９３年１０月,我们对引进白暨豚保护区湖北天鹅洲故道中试养的１１头江豚的生活状况和对环境的适应性,进行了较为详细的研究,力求在引入白暨豚前,对此地江豚的生活情况及白暨豚保护区的建区工作做进一步的生态评价。结果表明,江豚非常适应故道环境,它们能在其中正常生活,完成妊娠过程,顺利分娩,抚幼,幼体也能正常发育和成长。此外,故道还存     

High level population differentiation of finless porpoises (Neophocaena phocaenoides) in Chinese waters revealed by sequence variability of four nuclear introns

In the present study, sequence variations at four nuclear introns which were respectively from the parathyroid hormone-like (PTH) gene, isolate Pdalz1692 interferon (IFN) gene, peripherin-like (RDS) gene, and tyrosine kinase receptor-like (KIT) gene, were examined to analyze genetic diversity and population structure of the finless porpoise (Neophocaena phocaenoides) in Chinese waters. High among-population differentiation was revealed, with a significant genetic structure between populations (PTH: F(ST) = 0.29, P < 0.001; IFN1@: F(ST) = 0.23, P < 0.001; RDS: F(ST) = 0.12, P < 0.001; KIT: F(ST) = 0.16, P < 0.001) shown by the analysis of molecular variance. Although common haplotypes accounted for more than one half of all samples examined, many haplotypes were found to be population-specific. The Tajima's D, Fu's tests and mismatch distributions all suggested a recent colonization and population expansion of finless porpoises in Chinese waters. In view of special reference to the conservation priority of the Yangtze finless porpoises, special protection measures must be taken urgently for this population.