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China is unique among nations on account of its rich aquatic biodiversity (1443 inland fish species comprising 10% of those worldwide), status as the world’s largest producer (50%) of inland fish, and recent history of significant disruption of natural ecosystems. Ecological Civilization, a policy increasingly advocated in China since 2015, provides a strong platform to protect aquatic ecosystems and restore biodiversity in inland waters. We reviewed processes, policies, and outcomes related to inland fisheries and aquatic biodiversity during the 70 years since the establishment of the People’s Republic of China. Particular focus was on recent transformations in inland fisheries development and protection of inland aquatic biodiversity (IAB) under the goals of China’s recent Ecological Civilization policy. We describe how Chinese inland fisheries have undergone three transformative historical phases, (1) rapid development, (2) over-exploitation, and (3) vigorous protection. A series of newly introduced policies and programs hold promise for rehabilitating IAB. Global implications are considered by comparison with many of the world’s major river basins. We highlight the challenge of balancing fisheries development with biodiversity conservation; avoiding incidental adverse effects on conservation; rationalizing development under protection; eliminating gaps between protected areas, averting extinction and restoring endangered species; and integrating protection in managing watershed ecosystems. In the context of the global decline in freshwater biodiversity, the 70 years of fisheries development and biodiversity conservation in Chinese inland waters serve as a leading example for global IAB.

The river–reservoir transitional zones play an important role in maintaining riverine fish biodiversity and abundance in highly regulated rivers. The Upper Yangtze River, which contains 286 fish species, is experiencing intense hydropower development. However, few studies have been conducted on the spatial distribution of fish in the river–reservoir transitional zones in the Upper Yangtze River, and it is therefore difficult to predict how this development will impact the region. In this study, a 200-kHz split-beam acoustic system in combination with biological samplings was used to investigate the composition and spatiotemporal distribution of the fish in the transition zone of the Three Gorges Reservoir (TGR) in 2017. The biological samplings comprised 7434 individuals from 61 species, 38 genera, 15 families, and 5 orders. The dominant fish species were Rhinogobio cylindricus, Coreius guichenoti, Hemiculter bleekeri, and Pelteobagrus vachelli. Acoustic detection identified the mean target strength (TS) to be −55.6 in May, −57.8 in August, and −55.8 dB in December. Accordingly, the average fish density was 4.96, 6.96, and 4.42 ind/1000 m3. Significant differences were found in the TS and fish density between flood season (August) and non-flood season (May and December). Spatially, fish preferred the meandering sections at 10–20 m deep. A size-dependent vertical distribution pattern was observed, with larger fish in the deeper layers and smaller fish in shallower waters. Lastly, our results suggest that meandering deep channels should be assigned high priority with respect to fish conservation in the Upper Yangtze River.

Understanding the spatial dynamics of tuna fisheries in relation to prey biomass and environmental variability is crucial for sustainable management in the Indian Ocean; however, the direct links between tuna catches and prey biomass remain insufficiently resolved. This study examined the relationships between prey biomass and catches of skipjack, bigeye, and yellowfin tuna, together with their spatial and environmental drivers in the western Indian Ocean, by integrating acoustic surveys (38 kHz), zooplankton sampling, Indian Ocean Tuna Commission catch records, and satellite- and in situ -derived environmental data. Temperature, salinity, dissolved oxygen, and chlorophyll- a were analyzed at upper (47.4 m) and lower (130.7 m) depths of the thermocline. Tuna catches were highest in equatorial and northwestern regions, coinciding with elevated prey biomass, increased zooplankton density, and favorable environmental conditions. Catch patterns revealed depth-dependent environmental preferences, with warmer and more productive conditions favored at 47.4 m and cooler, high-salinity, and low-productivity conditions at 130.7 m, along with a pronounced spatial structure characterized by persistent high-catch zones in the northern and western regions. Despite limitations in sampling resolution and reliance on fishery-dependent data, this integrated approach provides valuable insights for ecosystem-based management of tropical tuna fisheries under changing oceanographic conditions.

The Yangtze River has the third greatest water flow and is one of the most human-influenced rivers in the world. Since 1950, this river system has experienced drastic human interventions, leading to various environmental changes, including water temperature. In this study, based on observations during the past sixty years, we found that the seasonal temperature regime has been altered, both temporally (1–5 °C variation) and spatially (>626 km distance). Temperature shifts not only delay the timing of fish spawning directly, but also lead to degeneration in gonad development. Temperature regime alterations have delayed the suitable spawning temperature window by approximately 29 days over a decade (2003–2016). It confirmed that a period of lower temperature, higher cumulative temperature, and relatively higher temperature differences promoted the maturation of potential spawners based on the correlation analysis (p < 0.05). Also, thermal alterations were highly correlated with reservoir capacity upstream (R2 = 0.866). On-going cascade dam construction and global warming will lead to further temperature shifts. Currently, rigorous protection measures on the breeding population of the Chinese sturgeon and its critical habitats is urgently needed to prevent the crisis of the species extinction. Increasing river thermal shifts not only threaten the Chinese sturgeon but also affect the entire Yangtze aquatic ecosystem.

Sound scattering layers (SSLs) are vital components of marine ecosystems, yet their morphometric and distributional characteristics remain understudied. This study investigates the SSL core in the southwestern Indian Ocean using a 38 kHz echosounder, focusing on its attributes across latitudinal gradients (20–4°S, 65°E) and three depth layers: epipelagic (0–100 m), intermediate (100–300 m), and mesopelagic (300–600 m). Our findings reveal the highest average acoustic values in the epipelagic layer (–72.9 dB), followed by the mesopelagic layer (–77.8 dB) and the intermediate layer (–82.5 dB). The SSL core was more prominent in northern latitudes (NLS) and showed greater depth variability in southern latitudes (SLS), with vertical profile peaks at 42.2 m and 431.1 m. In the NLS, the SSL core was longer (18,358 m > 6,788 m), thicker (13.8 m > 11.7 m), and more concentrated (aggregation index: 0.0053 m −1 > 0.004 m −1 ), as well as more dispersed from the center (inertia: 269.9 m² > 112.7 m²). Notably, depth and acoustic fluctuations were more pronounced over circadian cycles in the SLS than in the NLS. Multiple regression analysis revealed that oceanographic factors influencing acoustic values varied by depth, highlighting the complex interactions within SSL ecosystems. These insights enhance our understanding of SSL dynamics and their implications for long-term monitoring and climate influence assessment.

In global oceans, ubiquitous and persistent sound scattering layers (SL) are frequently detected with echosounders. The southwest Indian Ocean has a unique feature, a region of significant upwelling known as the Seychelles-Chagos Thermocline Ridge (SCTR), which affects sea surface temperature and marine ecosystems. Despite their importance, sound SL within and beyond the SCTR are poorly understood. This study aimed to compare the characteristics of the sound SL within and beyond the SCTR in connection with environmental properties, and dominant zooplankton. To this end, the region north of the 12°S latitude in the survey area was defined as SCTR, and the region south of 12°S was defined as non-SCTR. The results indicated contrasting oceanographic properties based on the depth layers between SCTR and non-SCTR regions. Distribution dynamics of the sound SL differed between the two regions. In particular, the diel vertical migration pattern, acoustic scattering values, metrics, and positional properties of acoustic scatterers showed two distinct features. In addition, the density of zooplankton sampled was higher in SCTR than in the non-SCTR region. This is the first study to present bioacoustic and hydrographic water properties within and beyond the SCTR in the southwest Indian Ocean.

Krill play a crucial role in the transfer of energy in the marine food web, connecting primary producers and the upper trophic levels in the Terra Nova Bay polynya (TNBP), which is part of the Ross Sea marine protected area. Despite the substantial ecological importance of krill, there are few studies on their distribution and abundance in the TNBP. An acoustic survey was conducted on 7‒14 January 2019 in the TNBP, Ross Sea, using a Simrad EK60 echosounder (38 and 120 kHz) aboard the icebreaker RV Araon. The most commonly used range of the difference of the mean volume backscattering strength (2–16 dB) was applied to distinguish krill. The acoustic data (120 kHz) were extracted to examine the krill distribution characteristics. The study area was divided into low-value areas and high-value areas based on the third quartile of the nautical area scattering coefficient. The results showed that the krill aggregations were distributed in three layers at depths of 0‒30 m, 70‒110 m, and 270‒300 m. The interpolated environmental parameters associated with the backscattering strength were compared. High-value areas of krill coincided with relatively low temperature, low salinity, and high chlorophyll, although very weak correlations were found. The primary goal of this study was to understand the vertical and horizontal distributions of krill acoustic biomass and to relate the observed patterns to the dominant environmental conditions.

BackgroundRamucirumab improves survival in gastric cancer patients. The efficacy and safety of ramucirumab outside of a clinical trial were evaluated using an expanded access program (EAP).MethodsAdvanced gastric cancer patients treated with ramucirumab in combination with paclitaxel or with ramucirumab monotherapy in a Korean EAP were evaluated. Baseline characteristics were assessed for progression-free survival (PFS) and overall survival (OS), and adverse events were evaluated according to the treatment regimen.ResultsOf 265 patients, 228 received ramucirumab plus paclitaxel, and 37 received ramucirumab monotherapy. Grade 3 or 4 neutropenia was more common with ramucirumab plus paclitaxel than with ramucirumab monotherapy (46.7 vs. 8.1%). Gastrointestinal (GI) perforation developed in seven patients (3.1%) in the ramucirumab plus paclitaxel group. The overall response and disease control rates were 16.6 and 66.3% in the ramucirumab plus paclitaxel group, and 5.4 and 37.8% in the ramucirumab monotherapy group, respectively. PFS and OS were 3.8 and 8.6 months in the ramucirumab plus paclitaxel group, and 1.8 and 6.4 months in the ramucirumab monotherapy group, respectively. In multivariate analysis, alkaline phosphatase, albumin, and neutrophil-to-lymphocyte ratio (NLR) were the independent prognostic factors for PFS, while albumin, NLR, number of metastatic sites, and large amount of ascites were independent prognostic factors for OS.ConclusionIn the Korean EAP cohort, ramucirumab showed similar efficacy to the results of the previous trials for gastric cancer. However, the level of GI perforation was slightly increased in the ramucirumab plus paclitaxel group.

Hydroacoustic surveys were conducted to understand the relationship between fish density, spatial distribution, and behavior upstream and downstream of the Changzhou Dam on the Pearl River, China, and the condition (open/closed) of the spillways. When the spillways were open on 24 June 2010, numerous fish were observed to be densely distributed in the forebay upstream of the dam, with an average fish density was 0.22 fish m −3 . When the spillways were closed on 25 June 2010, the fish upstream of the dam dispersed, and the average fish density decreased to 0.007 fish m −3 . Prior to operating the spillways on 24 May 2010, the average fish density downstream of the dam was 0.28 fish m −3 ; in comparison, on 26 June, immediately following closure of the spillways, the average fish density downstream of the dam was 0.08 fish m −3 . Fish were more active on June 24 than on 25 June: they swam faster and their positions in the water column varied greatly. On 26 June, fish did not to swim as freely in the water column as those measured on 24 May. Based on these observations, we conclude that a large number of fish are able to swim to the upstream side of the dam while the spillways are open.

The Chinese sturgeon, Acipenser sinensis, is a large anadromous and highly endangered protected species. The assessment of its breeding population in the Yangtze River is critically important for effective management and population preservation. Currently, hydroacoustic methods have been widely used to study the adult sturgeons in the river, whereas the acoustic target strength (TS) characteristics of the species have not been studied. In this study, the TS of Chinese sturgeon was carefully evaluated both by ex situ measurements and theoretical calculations. Six Chinese sturgeons (Body Length (BL): 74.0−92.6 cm) were measured by a 199 kHz split echosounder in a 10-m deep net cage. The computed tomography of a Chinese sturgeon (BL: 110.0 cm) was conducted and the Kirchhoff ray mode (KRM) method was used to estimate the theoretical TS. As a result, the mean ex situ TS range of the six specimens was from −26.9 to −31.4 dB, which was very close to the KRM estimation (~1 dB difference). Then, the KRM method was used to predict the TS of Chinese sturgeon as a function of BL in six frequencies commonly used in freshwater environments and to estimate the TS of a representative adult Chinese sturgeon (250 cm) as a function of frequency and tilt angle. This study can provide a good basis for future hydroacoustic studies on the critically endangered Chinese sturgeon.