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Soundscapes are vital to acoustically specialized animals. Using passive acoustic monitoring data, the temporal and spectral variations in the soundscape of a Chinese white dolphin hotspot were analyzed. By cluster analysis, the 1/3 octave band power spectrum can be grouped into three bands with median overall contribution rates of 35.24, 14.14 and 30.61%. Significant diel and tidal soundscape variations were observed with a generalized linear model. Temporal patterns and frequency ranges of middle frequency band sound matched well with those of fish vocalization, indicating that fish might serve as a signal source. Dolphin sounds were mainly detected in periods involving low levels of ambient sound and without fish vocalization, which could reflect noise avoidance and passive eavesdropping behaviors engaged in by the predator. Pre-construction data can be used to assess the effects of offshore windfarms on acoustic environments and aquatic animals by comparing them with the soundscape of postconstruction and/or postmitigation.

Identifying seasonal high-use habitats and migration corridors is the basis for migratory species conservation. Previous studies have focused on Marine Protected Areas, while freshwater ecosystems, often accompanied by severe hydrological fluctuations, suggest new perspectives for flexible management. Poyang Lake is an essential habitat for the critically endangered Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis, YFP), supporting almost half of their natural population. However, studies on the movement patterns and habitat preferences of YFPs still lack there, preventing potential protected areas’ effectiveness. In this study, we conducted 10 surveys for the YFP population in the main body and tributaries of Poyang Lake from October 2018 to August 2020. We used habitat modeling to analyze their seasonal habitat use and the environmental predictors. YFPs showed a seasonal movement pattern consistent with water level fluctuations. They entered the tributaries from the main lake body in low and medium water levels and returned to the main lake during high water level periods. The water depth was the most important environmental variable in each hydrological season that affects YFPs’ habitat selection. The suitable water depth was about 4-8 m during the low water level, 6-12 m during the medium water level, and 7-20 m during the high water level. YFPs’ 50% core habitats distribution showed noticeable seasonal changes. The proportion of their suitable habitats in the whole lake was relatively low, which was highest during high water level (16.89%), and the weakest during low water level (12.11%). Considering the seasonal movements of the YFPs in the lake, we recommend flexible management measures for their core habitats to alleviate human interference and restore their movement rhythm between the river and the lake, which shed light on protected area management for aquatic animals in such seasonal fluctuating habitats.

The Yangtze River exhibits a high biodiversity and plays an important role in global biodiversity conservation. As the world's busiest inland river in regard to shipping, little attention has been paid to underwater noise pollution. In 2017, the underwater noise level in 25 riverside locations along the middle and lower reaches of the Yangtze River mainly at night time were investigated by using passive acoustic monitoring method. Approximately 88% and 40% of the sampled sites exhibit noise levels exceeding the underwater acoustic thresholds of causing responsiveness and temporary threshold shift, respectively, in cetacean. Noise pollution may impose a high impact on fish with physostomous swim bladders and Weberian ossicles, such as silver carp, bighead carp, goldfish and common carp, whereas it may affect fish with physoclistous swim bladders and without Weberian ossicles, such as lake sturgeon and paddlefish, to a lesser extent. Noise levels reductions of approximately 10 and 20 dB were observed in the middle and lower reaches, respectively, of the Yangtze River over the 2012 level. The green development mode of the ongoing construction of green shipping in the Yangtze River Economic Belt, including the development of green shipping lanes, ports, ships and transportation organizations, may account for the alleviated underwater noise pollution. Follow-up noise mitigation endeavors, such as the extension of ship speed restrictions and the study and implementation of the optimal navigation speed in ecologically important areas, are required to further reduce the noise level in the Yangtze River to protect local porpoises and fish.

The Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) is the world's only freshwater porpoise and is endemic to the Yangtze River. However, it is now Critically Endangered, with its long-term survival very uncertain due to escalating anthropogenic pressure. Recent census data indicate an accelerating rate of decline, meaning that the time remaining in which to save this endemic porpoise may be shorter than previously anticipated. In this study, we used VORTEX models to project population trends and estimate the time to extinction (TE) for wild Yangtze finless porpoise populations in the Yangtze River, Dongting Lake and Poyang Lake, and for the “semi-natural” porpoise population in the Tian'e-Zhou oxbow reserve, using the most recent available baseline population data. The median predicted TE was 25–33 years in the Yangtze River and 37–49 years overall in the wild at the current rate of decline. However, the actual TE is very likely to be shorter than this estimate. For the Tian'e-Zhou population, the VORTEX model predicted a provisional increase in the number of porpoises, but a high extinction risk with increasing inbreeding depression. These findings highlight the very narrow time window within which effective conservation measures need to be undertaken. We address the need to establish a network of “reintroduction refuges” to preserve as many porpoise individuals as possible through coordinated translocations. Actions to restore the movement of porpoises between the main Yangtze channel and its appended lakes, reduction of mortality rates in lake habitats, and restoration of ecosystem function in the Yangtze River should also be implemented with a catchment-wide perspective.

Analyses of animal species distribution in a neutral or minimally-interrupted habitat provide a baseline that is essential for assessment of population status, identification of key habitat, and conservation planning for habitat protection and restoration. In this study, we surveyed the occurrence of the Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) and corresponding habitat characteristics, including bathymetry, benthic slope and fish resources, in the newly established He-wang-miao reserve. Based on sightings from field surveys, the extent of occurrence of the finless porpoise was 9.532 km2. General linear model analysis indicated the distribution of the finless porpoise was influenced by water depth and fish density. Habitat preference analysis illustrated a proxy to identify key habitat for the finless porpoise: moderate water depth (between 7 m and 12 m), flat benthic slope (lower than 2°) and moderately-high fish density (0.6 ind/m3 and 1.2 ind/m3). We proposed that this proxy has great potential for conservation planning to identify habitat conservation priorities in the Yangtze River and to guide management actions such as ex situ reserve selection and habitat restoration.

Shipping has increasingly become a major threat to cetaceans due to its direct effect (e.g. ship strikes) and indirect effects (e.g. noise and habitat displacement). Most previous studies have focused on the deleterious effects of shipping traffic on marine species, while the effect of shipping on freshwater cetaceans has received little attention. The Yangtze River is a major trade artery in China, and shipping traffic there caused deaths of the now-extinct Yangtze river dolphin or baiji (Lipotes vexillifer). Here, we examine the distributional overlap of another cetacean species, the critically endangered Yangtze finless porpoise (Neophocoena asiaorientalis asiaorientalis) and cargo ships in a busy section of Yangtze River from Ezhou to Zhenjiang City. We use vessel-based survey data from 2006, 2012, and 2017 to quantify the distribution of porpoise. We use satellite images to quantify the distribution of cargo vessels travelling upstream. Most porpoise were concentrated within 300 m of the river banks. Shipping increased by 65% from 2006 to 2017, and ~ 60% of the upstream vessels was also within 300 m of the banks. This increase in shipping may have caused an observed shift in porpoise distribution away from the banks after 2006. Enhanced enforcement of existing shipping regulations that limit vessels to established shipping lane and set refuges in the side channels could help reduce the distributional overlap of porpoise and ships and aid in porpoise conservation. This could be applied and benefit the cetacean conservation under continued growth of shipping in rivers.

Little effort has been made to conserve the East Asian finless porpoise, which is hindered by a lack of robust baseline data on their population status and threats. We conducted a local ecological knowledge survey around south Bohai Sea to collect information about the spatio-temporal distribution, population trends, and threats to East Asian finless porpoises. Based on the local ecological knowledge of 186 fishermen, April and September were the two months when porpoises were most frequently sighted, while February, November and December were when sightings were rare. Western coastal of Laizhou Bay and southern regions around Yellow River Estuary were identified as hotspots for sightings. More than half of the fishermen reported an overall decline in population through increasing water pollution, lower food resources and sustained fishery bycatch. These results provide insights into the distribution pattern and seasonal trends of the East Asian finless porpoises living in south Bohai Sea, thereby providing useful information for local authorities tasked with protecting this endangered cetacean.

Underwater sound plays an important role in some critical life functions of many aquatic animals. Underwater noise pollution has received relatively more attention in ocean systems. However, little attention has been paid to freshwater systems, such as the Yangtze River which is the habitat of critically endangered Yangtze finless porpoises (Neophocaena asiaeorientalis asiaeorientalis). In 2012, the underwater noise levels in 25 sites along the middle and lower sections of the Yangtze River were measured. The root mean square sound pressure level (SPL) and unweighted sound exposure level (SEL) at each site ranged between 105 ± 2.4 (median ± quartile deviation) and 150 ± 5.5 dB. Obvious spatial and temporal variations in the SPL were detected among the 25 sites. The SPL and SEL in the middle section of the Yangtze River were smaller (approximately 15 dB) and fluctuated more compared to those in the lower section. The power spectrum in the mainstem was site specific. However, all the spectra levels were higher than the audiogram of Yangtze finless porpoises. Majority of the sites had an averaged cumulative unweighted SEL (72%) and cumulative weighted SEL (68%) that surpassed the underwater acoustic thresholds for onset of hearing temporal threshold shifts for finless porpoise. Porpoise bio-sonars were detected in 89% of sonar monitoring sites indicating that noise pollution in the Yangtze River greatly threatened porpoise survival. In 8% of the sites, the averaged cumulative weighted SEL exceeded that of underwater acoustic thresholds causing non-recoverable permanent threshold shifts of finless porpoises auditory system whereas it was less than 1 dB below the underwater acoustic thresholds in other 8% of the sites. These sites urgently needed noise mitigation and management strategies. These results will facilitate the evaluation of the impacts of anthropogenic noise pollution on local finless porpoises and give further guidelines on its effective conservation.

The Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis), has experienced rapid declines in recent decades. We estimate its abundance based on surveys conducted between November and December 2017 in the main-stem of the Yangtze River and adjacent Poyang and Dongting Lakes. We compare these to published abundance estimates from 2006 and 2012, using a bootstrap resampling approach to make inference about population change over the 2006–2017 time period. Encounter rates of porpoise from additional surveys during this period provided another index for evaluating temporal changes in abundance in Poyang and Dongting Lakes. As of December 2017, free-ranging populations of this species are estimated at 1012 (95%CI: 791–1233) individuals of which 445 (95%CI: 295–595) occur in the main stem of the Yangtze River, 457 (95%CI: 329–634) in Poyang Lake, and 110 (95%CI: 65–187) in Dongting Lake. Porpoise numbers in main-stem of the Yangtze River and Dongting Lake declined rapidly from 2006 to 2012 (mean annual rates of −14% and −12%, respectively). These rates of decline greatly eased from 2012 to 2017 (−2.5% and +3% annual growth, respectively). In Poyang Lake, the encounter rates of porpoise have remained relatively stable between 2006 and 2017. This improved population trajectory was likely a joint consequence of government and public conservation efforts. However, fragmentation of porpoise populations in Yangtze River main-stem and significantly reduced migratory movements between the two adjoining lakes and the Yangtze main stem pose a continued threat to the long-term viability of this species. Further actions to improve habitat connectivity are urgently needed.

Pharmaceutical and personal care products (PPCPs) residues are being highlighted around the world as of emerging concern in surface waters. Here the occurrence of PPCPs in the central and lower Yangtze River, along with four large freshwater lakes within the river basin (Dongting, Poyang, Tai, and Chao) was reported. Fifteen out of twenty selected PPCPs were detected in the collected surface water samples. Caffeine, paraxanthine, sulfamethazine, and clindamycin were detected with 100 percent frequency in the Yangtze River. In the river, the highest average concentration was observed for erythromycin (296 ng L-1), followed by caffeine (142 ng L-1) and paraxanthine (41 ng L-1). In the four lakes, total PPCP concentrations were much higher in the Chao (1547 ng L-1) and Tai (1087 ng L-1) lakes compared to the Poyang (108 ng L-1) and Dongting (137 ng L-1) lakes. Lincomycin and clindamycin were most abundant in the lakes, especially in the Tai Lake. Environmental risk assessment for the worst case scenario was assessed using calculated risk quotients, and indicates a high environmental risk of erythromycin and clarithromycin in the Yangtze River, clarithromycin in the Chao Lake, and clindamycin in the Tai Lake. (C) 2014 Elsevier Inc. All rights reserved.

For the conservation of endangered animals to be effective, information on population distribution and abundance requires regular updating from census efforts. The Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) has recently been reclassified as critically endangered (CR) due to a rapid decline in abundance. Baseline measures currently used for identifying extinction risk and implementing conservation actions may lag behind the actual demographic trend of a population and, thus, should be updated frequently. In this study, we report the results of a line transect survey of porpoises conducted in the middle and lower reaches of the Yangtze River in 2012. Five hundred and five porpoises (95% CI = 348 to 662, CV = 15.86%) remain in the main stem of the Yangtze River, mostly concentrated between Ezhou and Zhenjiang. Our results reveal that the decline in the Yangtze finless porpoise population is more rapid than previously estimated. The porpoise distribution has become more restricted and fragmented with two new gaps in their distribution. We show that the extinction risk for the Yangtze finless porpoise population has increased substantially and, hence, the expected time to extinction has moved closer. Current conservation methods are insufficient and ineffective, and need to be revised. More active conservation actions, such as enforcing year-long fishing bans in the in situ reserves and building more ex situ reserves, should be implemented urgently. (C) 2014 Elsevier Ltd. All rights reserved.

middle and lower reaches of the Yangtze River, China. It is the only freshwater population of porpoises in the world and is currently listed as Endangered by IUCN. In November and December 2006 we used two boats and line transect methods to survey the entire current range of the population, except for two lakes (Poyang and Dongting). Sighting results were similar for both boats, so we pooled all data and analyzed them using two line transect models and a strip transect model. All models produced similar estimates of abundance (1111, 1225 and 1000). We then added independent estimates of the number of porpoises from the two lakes for a total estimate of approximately 1800 porpoises. Our findings indicate that the population continues to decline and that its distribution is becoming more fragmented. Our current estimate in the main river is slightly less than half the estimate from surveys between 1984 and 1991 (which was probably an underestimate). We also found an apparent gap in the distribution of porpoises between Yueyang and Shishou (similar to 150 km), where sightings had previously been common. Continued threats to Yangtze finless porpoises include bycatch in unregulated and unselective fishing, habitat degradation through dredging, pollution and noise, vessel strikes and water development. Immediate protective measures are urgently needed to ensure the persistence of finless porpoises in the Yangtze River. The survey design and analytical methods developed in this study might be appropriate for surveys of cetaceans in other river systems. (c) 2008 Elsevier Ltd. All rights reserved.

In order to increase drilling speed in deep complicated formations in Kela-2 gas field, Tarim Basin, Xinjiang, west China, it is important to predict the formation lithology for drilling bit optimization. Based on the conventional back propagation (BP) model, an improved BP model was proposed, with main modifications of back propagation of error, self-adapting algorithm, and activation function, also a prediction program was developed. The improved BP model was successfully applied to predicting the lithology of formations to be drilled in the Kela-2 gas field.

Echolocation behaviour of a harbor porpoise and six finless porpoises was recorded in open-water systems using acoustic data loggers (A-tag). In total 1359 click trains were recorded during 4.6 h for the harbor porpoise and 46,240 click trains were recorded during 82.3 h for the finless porpoises. The harbor and finless porpoises produced sonar click trains every 12.3 and 6.4 s on average, respectively. During the inter-click-train interval, the porpoises were silent or produced clicks below 148 dB re. View the MathML source, the detection threshold of the tag. Ninety percent of the inter-click-train intervals were 20 s or less in both species. This means that porpoises frequently produce intense click trains. Click-train intervals lasting over 50 s constituted 1% of the total intervals in finless porpoises and 4% in the harbor porpoise. Both species swam without intense clicks for less than 10 m in most cases, but occasionally remained silent or used undetected low-intensity clicks for more than 1 min. During these periods, the porpoises would be susceptible to entanglement in fishing nets.