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18 pages, 1243 KB

Open AccessArticle

Environmental Responses and Interspecific Associations of Fish Communities in the Zhoushan Fishing Ground Revealed by HMSC

by Xiaoyan Mao, Jing Wang, Yang Liu, Hui Ge, Haichen Zhu, Yongdong Zhou, Hongliang Zhang, Mingyang Xie and Wenbin Zhu

Animals 2026, 16(6), 865; https://doi.org/10.3390/ani16060865 - 10 Mar 2026

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Abstract

The fish community structure of the Zhoushan Fishing Ground is undergoing change due to overfishing, climate variability, and other anthropogenic stressors. To investigate community-level environmental responses and interspecific associations in this region, we used 11 consecutive years (2014–2024) of spring bottom trawl survey [...] Read more.

The fish community structure of the Zhoushan Fishing Ground is undergoing change due to overfishing, climate variability, and other anthropogenic stressors. To investigate community-level environmental responses and interspecific associations in this region, we used 11 consecutive years (2014–2024) of spring bottom trawl survey data from the Zhoushan Fishing Ground and integrated environmental covariates to build a two-part hurdle model within the Hierarchical Modelling of Species Communities (HMSC) framework. The results showed that the spatial random effect had the highest contribution (41%), followed by the interannual trend (18%), indicating that community occurrence patterns are primarily shaped by the superposition of stable spatial structuring and long-term change. Depth was significant for more species, whereas salinity was significant for the fewest. Residual correlations further revealed that the focal fish species could be partitioned into two assemblages with one linking species. Meanwhile, within the two-part hurdle model, the direction and significance of responses to the same covariate were not always consistent, supporting that species occurrence probability and positive biomass are governed by different ecological processes. Overall, this study provides a transferable quantitative framework for community assessment in coastal fishing grounds and offers a more operational chain of evidence for ecosystem-based fisheries management. Full article

(This article belongs to the Special Issue Changes in Population Characteristics of Marine and Freshwater Organisms and Their Environmental Driving Factors)

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25 pages, 2394 KB

Open AccessArticle

Impacts of Winter and Spring Water Masses on Demersal Fish Community Structure Around Hainan Island

by Boran Qin, Jiani Dong, Jiajie Chen, Yuange Chen, Wei Tian, Xiaodong Wang and Junsheng Zhong

Animals 2026, 16(5), 809; https://doi.org/10.3390/ani16050809 - 5 Mar 2026

Viewed by 462

Abstract

To elucidate water mass impacts on fish diversity in Hainan Island, bottom trawl surveys were conducted at 50 stations around the Island in December 2023 (winter) and April 2024 (spring). K-means clustering identified three water masses: Coastal Water (CW), Mixed Water (MW), and [...] Read more.

To elucidate water mass impacts on fish diversity in Hainan Island, bottom trawl surveys were conducted at 50 stations around the Island in December 2023 (winter) and April 2024 (spring). K-means clustering identified three water masses: Coastal Water (CW), Mixed Water (MW), and Offshore Water (OW). A total of 396 species were collected. Winter communities demonstrated clear habitat specificity, with distinct dominant species in each water mass (OW, MW, and CW). Conversely, the spring intrusion of warm, saline water facilitated the dominance of migratory species in the MW. Diversity centers shifted significantly northward and shoreward, transitioning from the MW region in winter to the CW region in spring. These findings highlight the critical influence of seasonal hydrodynamics on fish community structure, providing essential baselines for regional fisheries management and conservation. Full article

(This article belongs to the Special Issue Changes in Population Characteristics of Marine and Freshwater Organisms and Their Environmental Driving Factors)

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27 pages, 4749 KB

Open AccessArticle

Image-Based Analysis of Morphometric Differences Between Sea-Caught and Farmed Large Yellow Croaker (Larimichthys crocea)

by Yatong Yao, Quanyou Guo, Shengmao Zhang, Junjie Wu, Tianfei Chen, Na Lin, Zuli Wu and Hanfeng Zheng

Animals 2026, 16(4), 601; https://doi.org/10.3390/ani16040601 - 14 Feb 2026

Viewed by 451

Abstract

Morphological differences between sea-caught and farmed fish reflect environmental conditions and long-term domestication. However, standardized and objective quantification of these differences remains limited for many commercially important species. The large yellow croaker (Larimichthys crocea) represents a typical marine fish with clear [...] Read more.

Morphological differences between sea-caught and farmed fish reflect environmental conditions and long-term domestication. However, standardized and objective quantification of these differences remains limited for many commercially important species. The large yellow croaker (Larimichthys crocea) represents a typical marine fish with clear contrasts between natural and aquaculture production systems. In this study, an image-based phenotyping workflow was developed to quantify external morphological traits of sea-caught and farmed L. crocea. Visible-light images were acquired under standardized conditions. A YOLOv11-based instance segmentation model was applied to automatically delineate major anatomical regions, including the body, head, eyes, pectoral fins, and tail. Surface areas and proportional indices were calculated following geometric calibration to ensure measurement consistency. The segmentation model achieved high accuracy on the test dataset (mAP@50 > 98%). Morphometric analyses revealed clear differences between the two groups. Farmed individuals exhibited larger body-related surface areas, whereas the relative proportions of pectoral fins and tail regions were reduced. Sea-caught fish showed higher proportional investment in locomotor structures, consistent with the physical demands of natural marine environments. These results indicate a shift in morphological allocation associated with aquaculture, characterized by enhanced trunk growth and reduced relative development of propulsion-related structures. The proposed workflow provides a rapid, non-invasive, and reproducible approach for fish morphometric analysis. It offers practical potential for phenotypic monitoring and stock assessment, while contributing quantitative evidence for domestication-driven morphological divergence in marine fishes. Full article

(This article belongs to the Special Issue Changes in Population Characteristics of Marine and Freshwater Organisms and Their Environmental Driving Factors)

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16 pages, 1369 KB

Open AccessArticle

Life-History Plasticity of Cultured Coreius guichenoti: Energy Allocation Trade-Offs and Conservation Applications

by Miao Xiang, Haoran Liu, Zihao Meng, Yan Zhao, Chengjie Yin, Xuemei Li, Xingbing Wu and Tingbing Zhu

Animals 2026, 16(3), 456; https://doi.org/10.3390/ani16030456 - 1 Feb 2026

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Abstract

Coreius guichenoti, an endemic fish of the upper Yangtze River, has experienced severe population decline due to overfishing and habitat fragmentation. To inform its conservation, this study compared life-history traits between artificially bred and historical wild populations, revealing pronounced plasticity in response [...] Read more.

Coreius guichenoti, an endemic fish of the upper Yangtze River, has experienced severe population decline due to overfishing and habitat fragmentation. To inform its conservation, this study compared life-history traits between artificially bred and historical wild populations, revealing pronounced plasticity in response to environmental conditions. The cultured population, dominated by age 0–4 individuals but retaining a notable proportion of age 5–6 fish, exhibited faster growth and higher fecundity (mean absolute fecundity 32,724 ± 24,132 eggs; relative fecundity 37.5 ± 18.5 eggs/g) than the wild population. In contrast, the wild group consisted of >90% age 0–4 individuals, showed virtually no fish aged 5–7, reproduced seasonally with high total egg output, and tended toward a periodic life-history strategy, whereas the cultured group tended toward an opportunistic strategy that still retained some periodic traits. These results demonstrate that C. guichenoti can adjust its life history on a within-generation scale. Accordingly, we recommend pre-release conditioning with moderate flow and temperature variations to enhance field adaptability. This study provides evidence-based guidance for broodstock selection and preconditioning in restocking programs, aimed at improving post-release survival and reproductive success in the wild. Full article

(This article belongs to the Special Issue Changes in Population Characteristics of Marine and Freshwater Organisms and Their Environmental Driving Factors)

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18 pages, 6529 KB

Open AccessArticle

Geostatistical Analysis of the Variability in Sthenoteuthis oualaniensis Fishing Grounds in the Northwestern Indian Ocean High Seas

by Ruizhi Zhou, Hanfeng Zheng, Yongchuang Shi, Lingzhi Li, Wei Fan, Ziniu Li, Guoqing Zhao and Fenghua Tang

Animals 2026, 16(3), 393; https://doi.org/10.3390/ani16030393 - 27 Jan 2026

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Abstract

Sthenoteuthis oualaniensis is a major commercial species in the high-seas fisheries of the northwestern Indian Ocean. However, its spatiotemporal distribution exhibits strong uncertainty under climate and environmental variability, complicating the understanding of fishing ground dynamics. To investigate the spatiotemporal distribution of S. oualaniensis [...] Read more.

Sthenoteuthis oualaniensis is a major commercial species in the high-seas fisheries of the northwestern Indian Ocean. However, its spatiotemporal distribution exhibits strong uncertainty under climate and environmental variability, complicating the understanding of fishing ground dynamics. To investigate the spatiotemporal distribution of S. oualaniensis under climate change, this study analyzed commercial fishing data from 2016 to 2024. The results indicate that the core distribution area of the species is consistently concentrated within 14–19° N and 61–65° E. From 2016 to 2024, the fishing ground expanded annually and shifted overall toward the east and north, with its centroid showing a persistent northeastward trajectory. Global spatial autocorrelation analysis revealed positive and significant Moran’s I values for all years, demonstrating a strong spatial clustering pattern. Hotspot analysis shows that high-abundance areas were primarily located north of 14° N, with an overall northeastward migration trend. Hotspots expanded continuously from 2016 to 2023, but sharply contracted in 2024, shifting further northeast and becoming restricted to 63–68° E and 19–21° N. The GAM results indicate that CPUE in the region is jointly influenced by spatiotemporal drivers and multiple environmental factors. These findings confirm that the spatiotemporal distribution and population dynamics of S. oualaniensis are shaped by the combined effects of environmental variability and temporal–spatial factors, with environmental influences playing a particularly crucial role. Full article

(This article belongs to the Special Issue Changes in Population Characteristics of Marine and Freshwater Organisms and Their Environmental Driving Factors)

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17 pages, 7133 KB

Open AccessArticle

The Spatial and Temporal Distribution of Bigeye Tuna and Yellowfin Tuna in the Northwest Indian Ocean and Their Relationship with Environmental Factors

by Guoqing Zhao, Hanfeng Zheng, Chao Li, Yongchuang Shi, Fengyuan Shen, Hewei Liu, Jialiang Yang, Ziniu Li, Zhi Zhu and Lingzhi Li

Animals 2026, 16(2), 282; https://doi.org/10.3390/ani16020282 - 16 Jan 2026

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Abstract

The Northwestern Indian Ocean (NWIO) serves as a primary fishing ground for tuna longline fisheries, with bigeye tuna (Thunnus obesus) and yellowfin tuna (Thunnus albacares) constituting the main target species. Investigating their spatiotemporal distribution and relationship with environmental factors [...] Read more.

The Northwestern Indian Ocean (NWIO) serves as a primary fishing ground for tuna longline fisheries, with bigeye tuna (Thunnus obesus) and yellowfin tuna (Thunnus albacares) constituting the main target species. Investigating their spatiotemporal distribution and relationship with environmental factors is of significant importance for fishery management and fishing. This study analyzed and compared the distribution patterns and environmental preferences of these two species across different depth layers, based on fisheries scientific survey data collected during the 2023/2024 and 2024/2025 fishing seasons. Key findings include: The hook rate in 2023/2024 was higher than in 2024/2025, and the hook rate for T. obesus exceeded that of T. albacares. T. obesus were predominantly concentrated within 63° E–69° E and 7° N–9° N, while T. albacares exhibited a broader yet more dispersed distribution range. T. obesus primarily occupied depth layers of 130–140 m (12.20%), 180–190 m (9.76%), and 270–280 m (9.76%). T. albacares were mainly found at 110–120 m (15%), 140–150 m (15%), and 200–210 m (15%). Both species exhibit distinct spatial clustering patterns, and their hotspot distribution areas are, respectively, 63° E–69° E, 5° N–10° N and 64° E–68° E, 0° N–4° N. Correlation analysis revealed significant relationships between T. obesus distribution and latitude, zooplankton abundance, water temperature at various depths, and chlorophyll a concentration. Our research provides reference for understanding the distribution of T. obesus and T. albacares across different water layers and their habitat preferences, laying a scientific foundation for achieving sustainable utilization of both species. Full article

(This article belongs to the Special Issue Changes in Population Characteristics of Marine and Freshwater Organisms and Their Environmental Driving Factors)

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18 pages, 2518 KB

Open AccessArticle

Geographic Variation in Morphology and Physiology of Meretrix meretrix (Linnaeus, 1758) Along the Chinese Coast

by Jinmeng Bao, Yue Zhu, Longyu Liu, Shuai Han, Fengbiao Wang, Haopeng Hu, Xuan Zhang, Lei Li and Mei Jiang

Animals 2026, 16(1), 65; https://doi.org/10.3390/ani16010065 - 25 Dec 2025

Cited by 1 | Viewed by 744

Abstract

The clam Meretrix meretrix (Linnaeus, 1758) is a commercially significant bivalve species widely distributed along China’s coast. To investigate the differences among geoducks from different geographic populations, this study investigated the geographical variations in morphology and key physiological traits among three populations spanning [...] Read more.

The clam Meretrix meretrix (Linnaeus, 1758) is a commercially significant bivalve species widely distributed along China’s coast. To investigate the differences among geoducks from different geographic populations, this study investigated the geographical variations in morphology and key physiological traits among three populations spanning a latitudinal gradient: Liaoning Dandong (north), Jiangsu Rudong (center), and Guangxi Qinzhou (south). We analyzed nine morphological traits and measured physiological indicators—including filtration rate, feeding rate, oxygen consumption, ammonia excretion, and burrowing behavior—at two temperatures (18 °C and 20 °C). The results revealed significant morphological differentiation among the populations. Physiologically, the Guangxi population demonstrated superior adaptation to warmer conditions, exhibiting the highest feeding and metabolic rates at 20 °C. In contrast, the Liaoning population performed better at the lower temperature of 18 °C, while the Jiangsu population showed intermediate characteristics. Furthermore, burrowing capacity varied significantly, with the southern population having the highest burrowing rate. These findings demonstrate clear population-specific adaptations to local thermal environments, likely driven by long-term acclimatization. This study provides a crucial scientific basis for the conservation of genetic resources and informs regionalized aquaculture strategies for M. meretrix, emphasizing the importance of selecting locally adapted populations for cultivation. Full article

(This article belongs to the Special Issue Changes in Population Characteristics of Marine and Freshwater Organisms and Their Environmental Driving Factors)

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15 pages, 2195 KB

Open AccessArticle

Thermal Limits of the Estuarine Amphipod Melita palmata Under Different Salinities and Its Relevance for Aquaculture Production

by Luísa Marques, Daniela P. Rodrigues, Rafael C. Duarte and Ricardo Calado

Animals 2026, 16(1), 4; https://doi.org/10.3390/ani16010004 - 19 Dec 2025

Cited by 1 | Viewed by 967

Abstract

Estuarine organisms experience frequent fluctuations in salinity and temperature, facing major challenges to their physiological homeostasis. Such variability can promote high energetic costs for osmoregulation, potentially reducing tolerance to additional stressors. We investigated the effect of salinity on the thermal tolerance of the [...] Read more.

Estuarine organisms experience frequent fluctuations in salinity and temperature, facing major challenges to their physiological homeostasis. Such variability can promote high energetic costs for osmoregulation, potentially reducing tolerance to additional stressors. We investigated the effect of salinity on the thermal tolerance of the estuarine amphipod Melita palmata (Montagu, 1804), a species of growing interest for aquaculture, either as live feed or as a potential source for essential fatty acids in formulated diets. The critical thermal maximum (CTmax) was determined for males and females collected from three sites within a temperate coastal lagoon (Ria de Aveiro, Portugal) characterized by different salinity regimes (15, 20, and 30). Individuals from lower-salinity environments exhibited significantly lower CTmax values than those from higher salinities, indicating that osmoregulatory costs may restrict thermal resistance. No significant sex-based differences in CTmax were detected. However, thermal safety margins (TSMs) increased with salinity, indicating greater thermal tolerance under higher salinity conditions, and differences in body condition index (BCI) between sites suggest salinity-related effects on growth performance. These results highlight that the elevated energetic demands of osmoregulation under hypo-osmotic conditions can constrain the thermal limits of M. palmata, underscoring the complex trade-offs between environmental variability and physiological performance in estuarine habitats. Beyond its ecological implications, understanding the physiological responses of M. palmata to salinity and temperature is key, optimising its use in aquaculture. The species’ physiological plasticity under such variable conditions reinforces its suitability for aquaculture production, particularly in earthen ponds in estuarine environments. Full article

(This article belongs to the Special Issue Changes in Population Characteristics of Marine and Freshwater Organisms and Their Environmental Driving Factors)

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12 pages, 2041 KB

Open AccessArticle

Seasonal Spatial Distribution and Migration Patterns of the Shrimp Parapenaeus fissuroides in the Southern Yellow and East China Seas: Habitat Area Change Under Climate Scenarios

by Min Xu, Yong Liu, Yang Xu, Haisu Zheng, Jianzhong Ling and Huiyu Li

Animals 2025, 15(24), 3597; https://doi.org/10.3390/ani15243597 - 15 Dec 2025

Cited by 1 | Viewed by 527

Abstract

Shrimp populations are threatened by overfishing and climate change. Despite this, there are limited studies on the variations in biomass, number, and size of Eastern Neptune rose shrimp, Parapenaeus fissuroides, in different fishing grounds across seasons in the Southern Yellow and East [...] Read more.

Shrimp populations are threatened by overfishing and climate change. Despite this, there are limited studies on the variations in biomass, number, and size of Eastern Neptune rose shrimp, Parapenaeus fissuroides, in different fishing grounds across seasons in the Southern Yellow and East China Seas of China, as well as habitat area change under different climate scenarios. In this study, the data was obtained from the bottom trawling surveys conducted from November 2018 to September 2019 at 26.5–35° N 120–127° E. We found that the major cohorts were concentrated at depths of 70–110 m in spring and summer, 80–90 m in autumn, and 60–100 m in winter. The greatest abundance was observed at sea bottom temperatures of 18–20 °C in spring, 18–21 °C in summer, 19–22 °C in autumn, and 17–19 °C in winter; and sea bottom salinity levels of 34–35 across all four seasons, indicating the influence of high-salinity Taiwan Warm Current and Yellow Sea Warm Current. The annual mean catch per unit effort in weight and number were 16,623.65 g·h⁻¹ and 4304.525 ind·h⁻¹, respectively. Climate variations may negatively impact the habitat area range of P. fissuroides. For migration route, P. fissuroides concentrates in Yushan and Yuwai for the upcoming spawning season in spring, with offspring occurring in high-temperature and high-salinity waters of Zhouwai and Yuwai in summer. The newborn recruited cohorts remained in Yushan, Wentai, and Mindong for nursery grounds in autumn and winter. We suggested a seasonal closure from August to November in Yushan, Yuwai, Zhouwai, and Mindong to protect and conserve P. fissuroides populations. Full article

(This article belongs to the Special Issue Changes in Population Characteristics of Marine and Freshwater Organisms and Their Environmental Driving Factors)

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14 pages, 715 KB

Open AccessArticle

Comparative Study on Feeding Physiology, Metabolic Physiology, and Energy Budget of Meretrix meretrix, Mactra veneriformis, and Ruditapes philippinarum in the Tidal Flat Aquaculture Zone

by Longyu Liu, Yue Zhu, Chaozhong Xin, Jinmeng Bao, Fengbiao Wang, Shuai Han, Haopeng Hu, Xuan Zhang, Lei Li and Mei Jiang

Animals 2025, 15(24), 3543; https://doi.org/10.3390/ani15243543 - 9 Dec 2025

Viewed by 514

Abstract

(1) Exploring the potential impacts of Mactra veneriformis and Ruditapes philippinarum on the aquaculture of Meretrix meretrix in the tidal flat aquaculture zone is significant for the optimization of bivalve aquaculture structure. (2) In this study, we systematically compared the differences in feeding, [...] Read more.

(1) Exploring the potential impacts of Mactra veneriformis and Ruditapes philippinarum on the aquaculture of Meretrix meretrix in the tidal flat aquaculture zone is significant for the optimization of bivalve aquaculture structure. (2) In this study, we systematically compared the differences in feeding, metabolic physiological indicators, and energy budgets of the three bivalve species in the M. meretrix aquaculture zone of Rudong County, Jiangsu Province, under the feeding conditions of Isochrysis zhanjiangensis and Platymonas helgolandica. (3) The results indicated that feeding with I. zhanjiangensis could significantly improve the feeding efficiency of the three bivalve species, and M. veneriformis showed the strongest feeding ability. Under I. zhanjiangensis feeding conditions, the clearance rate [1.373 ± 0.177 L/(g·h)] and ingestion rate [9.803 ± 1.264 mg/(g·h)] of M. veneriformis were significantly higher than those of M. meretrix [clearance rate: 0.716 ± 0.046 L/(g·h); ingestion rate: 5.112 ± 0.328 mg/(g·h)] and R. philippinarum [clearance rate: 0.609 ± 0.101 L/(g·h); ingestion rate: 4.351 ± 0.725 mg/(g·h)] (p < 0.05). In terms of energy allocation, the scope for growth (SFG) of M. veneriformis [133.050 ± 15.705 J/(g·h)] was significantly higher than that of the other two bivalve species. M. meretrix [70.550 ± 2.133 J/(g·h)] had the highest energy utilization efficiency, while R. philippinarum [53.688 ± 7.548 J/(g·h)] had the lowest SFG due to high excretion losses. (4) In conclusion, M. veneriformis shows high production potential in the aquaculture system, and its potential impact on M. meretrix is greater than that of R. philippinarum, thus requiring close attention in aquaculture management. Full article

(This article belongs to the Special Issue Changes in Population Characteristics of Marine and Freshwater Organisms and Their Environmental Driving Factors)

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21 pages, 5620 KB

Open AccessArticle

Otolith Strontium Isotope (⁸⁷Sr/⁸⁶Sr) Reveals Mixed Life Histories of Coilia brachygnathus in the Middle–Lower Yangtze River Floodplain

by Zhongya Xuan, Yinping Wang, Sheng Wang, Yanping Yang, Chongrui Wang, Silei Liu and Kai Liu

Animals 2025, 15(23), 3434; https://doi.org/10.3390/ani15233434 - 28 Nov 2025

Viewed by 802

Abstract

Life-history plasticity allows fishes to exploit heterogeneous freshwater networks, and proactive habitat selection enhances their capacity to cope with climatic and human-induced stressors. Coilia brachygnathus, long regarded as a freshwater resident, nevertheless has a poorly understood habitat use and selection. We reconstructed [...] Read more.

Life-history plasticity allows fishes to exploit heterogeneous freshwater networks, and proactive habitat selection enhances their capacity to cope with climatic and human-induced stressors. Coilia brachygnathus, long regarded as a freshwater resident, nevertheless has a poorly understood habitat use and selection. We reconstructed habitat use of C. brachygnathus across the middle-lower Yangtze by coupling water ⁸⁷Sr/⁸⁶Sr baselines with otolith ⁸⁷Sr/⁸⁶Sr transects. We used 60 water samples, compiled published datasets, and measured additional water samples from the mainstem, major tributaries, and connected lakes. In situ ⁸⁷Sr/⁸⁶Sr profiles were smoothed with generalized additive models, revealing significant within-profile variation for all fish. Two modes emerged: (i) residents, whose otolith values remained within local water ranges, consistent with limited movement; and (ii) migrants, whose profiles departed from local baselines, indicating exchanges among lakes, tributaries, and the mainstem. Several fish captured at Anqing and Zhenjiang possess Poyang-like core signatures that declined to mainstem values, while bidirectional shifts were common in the Dongting-Xiang system. These results overturn the residency paradigm, demonstrate flexible partial migration, and indicate proactive habitat selection in the face of environmental change, thereby supporting management that maintains river–lake connectivity and quantifies lake contributions to mainstem stocks. Full article

(This article belongs to the Special Issue Changes in Population Characteristics of Marine and Freshwater Organisms and Their Environmental Driving Factors)

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18 pages, 3548 KB

Open AccessArticle

Spatial and Environmental Drivers of Summer Growth Variability and Adaptive Mechanisms of Euphausia crystallorophias in the Amundsen Sea and Its Adjacent Regions

by Jialiang Yang, Lingzhi Li, Shuai Li, Guoqing Zhao, Xin Rao, Shuai Chen, Hewei Liu, Fengyuan Shen, Hongliang Huang and Ziyi Wang

Animals 2025, 15(22), 3345; https://doi.org/10.3390/ani15223345 - 20 Nov 2025

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Abstract

Ice krill (Euphausia crystallorophias) play a key role in the Antarctic coastal ecosystem, yet its spatial growth variability remains poorly understood. This study examined 5298 krill individuals from 52 stations across the Amundsen Sea, transitional waters, and the Ross Sea, collected [...] Read more.

Ice krill (Euphausia crystallorophias) play a key role in the Antarctic coastal ecosystem, yet its spatial growth variability remains poorly understood. This study examined 5298 krill individuals from 52 stations across the Amundsen Sea, transitional waters, and the Ross Sea, collected between 2020 and 2024. Length–weight relationships (LWR) were constructed to derive the condition factor a and the allometric growth exponent b, followed by regional comparisons and environmental response analyses using boxplots, redundancy analysis (RDA), and generalized additive models (GAM). Boxplots revealed that a was significantly higher in the Amundsen Sea and transitional zone than in the Ross Sea, while b was highest and most variable in the Amundsen Sea. RDA indicated that a was primarily associated with depth, latitude, mean temperature, and mean salinity, whereas b was influenced by sea surface temperature, chlorophyll-a, sea ice concentration, and longitude. GAM further showed nonlinear responses of a to mean temperature, mean salinity, and depth, with peaks near −0.5 °C, 34.2 PSU, and 3500 m, respectively. These results suggest that krill in deep, cold, and less-productive transitional zone allocate more energy to body condition (high value a), while those in warmer, moderately productive regions like the Amundsen Sea invest more in structural growth (high value b). This study provides new insights into the environmentally driven growth strategies of ice krill and contributes to understanding its ecological adaptability under changing climatic and oceanographic conditions. Full article

(This article belongs to the Special Issue Changes in Population Characteristics of Marine and Freshwater Organisms and Their Environmental Driving Factors)

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19 pages, 2639 KB

Open AccessArticle

Tracking the Migratory Life History of Brown Croaker (Miichthys miiuy) Through Otolith Microchemistry in the East China Sea

by Jiarong Shen, Zeyu Xiao, Rijin Jiang, Zhongya Xuan, Yongdong Zhou, Wenjia Li, Haoran Wang, Jian Yang and Mingyuan Cui

Animals 2025, 15(21), 3129; https://doi.org/10.3390/ani15213129 - 29 Oct 2025

Cited by 1 | Viewed by 943

Abstract

Brown croaker (Miichthys miiuy) is an economically, ecologically, and culturally important species in the East China Sea (ECS); however, populations of M. miiuy have declined in recent years due to climate change and high fishing intensity. Our limited understanding of wild [...] Read more.

Brown croaker (Miichthys miiuy) is an economically, ecologically, and culturally important species in the East China Sea (ECS); however, populations of M. miiuy have declined in recent years due to climate change and high fishing intensity. Our limited understanding of wild M. miiuy’s migratory life history hampers effective population conservation. To meet this need, and to elucidate the migratory life history of wild M. miiuy, we quantified the elemental composition of otolith samples using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). This approach, combined with analysis of otolith microstructure, was used to evaluate the feasibility of using the Mg:Ca of otoliths chemical clock for M. miiuy. Using cluster analysis alongside bivariate time series analysis, we identified natal sources and reconstructed migratory histories. The results showed that consistent, periodic fluctuation of Mg:Ca ratios in otolith profiles can be used as a chemical index to indicate the age and life history stage of M. miiuy. Natal sources of M. miiuy originated from three distinct water environments: estuary (14.2%), coastal mixed waters (57.3%), and coastal reef waters (28.5%). A diverse migratory life history of M. miiuy was observed based on Sr:Ba thresholds, and ultimately, we identified four migratory life histories of the species, including an estuary–coastal migratory type, a coastal resident type, a coastal–offshore migratory type and an estuary–coastal–offshore migratory type. This study provides a scientific basis for the protection of key habitats and seasonal management of M. miiuy in the ECS. Full article

(This article belongs to the Special Issue Changes in Population Characteristics of Marine and Freshwater Organisms and Their Environmental Driving Factors)

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17 pages, 2600 KB

Open AccessArticle

Effects of Multiple Stressors on the Spatial Pattern of Fish Diversity in the Middle and Lower Reaches of the Han River, China

by Zhiyuan Qi, Fei Xiong, Xingkun Hu, Dongdong Zhai, Le Hu, Yanfu Que, Xinbin Duan, Yuanyuan Chen, Hongyan Liu and Bin Zhu

Animals 2025, 15(21), 3109; https://doi.org/10.3390/ani15213109 - 26 Oct 2025

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Abstract

Human activities have altered rivers worldwide, but how their combined effects shape fish assemblages remains unclear. We therefore surveyed fish and habitats seasonally along the middle and lower reaches of the Han River, China, during 2022, specifically in June–August (wet season) and October–November [...] Read more.

Human activities have altered rivers worldwide, but how their combined effects shape fish assemblages remains unclear. We therefore surveyed fish and habitats seasonally along the middle and lower reaches of the Han River, China, during 2022, specifically in June–August (wet season) and October–November (dry season). This study analyzed the spatial distribution pattern of fish diversity, explored the effects of natural factors (e.g., hydrology, water quality) and human stressors (e.g., dam, land use) on the spatial pattern of fish diversity, and identified the key driving factors. Cluster analysis and Non-metric Multidimensional Scaling (NMDS) showed that the fish communities could be divided into three groups: the Danjiangkou reservoir area (DRA), the middle reaches (MR), and the lower reaches (LR). For α-diversity, the LR had the highest value, followed by the DRA, with the MR being the lowest. For β-diversity, the MR had the highest value, followed by the LR, with the DRA being the lowest. Random Forest model showed that fish diversity was mainly affected by natural factors; among these factors, the key drivers of α-diversity were hydrological factors such as the water level (3.56–5.97%) and river width (4.53–4.69%), while for β-diversity, the key drivers were water quality factors, including the dissolved oxygen (10.08–12.36%), total nitrogen (6.49–9.31%), and chlorophyll a (8.26–8.40%). Structural Equation Modeling further revealed that natural factors affected β-diversity mainly through direct pathways, while human stressors affected β-diversity mainly through indirect pathways. The results revealed the differential roles of natural factors and human stressors in driving the patterns of fish α-diversity and β-diversity in human-disturbed rivers, which will provide a scientific basis for the conservation of fish diversity in the Han River. Full article

(This article belongs to the Special Issue Changes in Population Characteristics of Marine and Freshwater Organisms and Their Environmental Driving Factors)

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20 pages, 7424 KB

Open AccessFeature PaperArticle

Analysis of Relative Abundance Distribution and Environmental Differences for Blue Mackerel (Scomber australasicus) and Chub Mackerel (Scomber japonicus) on the High Seas of the North Pacific Ocean

by Heng Zhang, Hanji Zhu, Famou Zhang, Sisi Huang, Jianhua Wang, Delong Xiang, Yang Li and Yuyan Sun

Animals 2025, 15(19), 2822; https://doi.org/10.3390/ani15192822 - 27 Sep 2025

Viewed by 1693

Abstract

The accurate assessment and management of Blue Mackerel (Scomber australasicus) and Chub Mackerel (Scomber japonicus) resources in the high seas of the Northwest Pacific are constrained by the persistent issue of data misreporting in catch records, which arises from [...] Read more.

The accurate assessment and management of Blue Mackerel (Scomber australasicus) and Chub Mackerel (Scomber japonicus) resources in the high seas of the Northwest Pacific are constrained by the persistent issue of data misreporting in catch records, which arises from their high morphological similarity. This study integrates fishery logbooks and field sampling data from Chinese purse seine fleets (2014–2023), along with key oceanographic factors—six of which were finally selected after correlation analysis. We introduce, for the first time, a Zero-One Inflated Beta Model (ZOIBM) to analyze the spatiotemporal distribution of the relative abundance of these two mackerel species. Furthermore, a Generalized Additive Model (GAM) was employed to reveal the environmental mechanisms driving their niche differentiation. The results show that the ZOIBM demonstrates excellent performance (R² = 0.63, RMSE = 0.305), effectively quantifying the proportional composition of the two species in mixed catches. Spatially, high-abundance areas of Blue Mackerel were concentrated within 35–44° N, 145–160° E, with its proportion decreasing at higher latitudes. In contrast, Chub Mackerel exhibited an opposite latitudinal pattern, with its high-abundance areas covering a broader latitudinal range (35–47.5° N). The analysis of environmental drivers indicated that SST was the most critical factor for differentiation, while Chla and VO further amplified the divergence in resource utilization strategies between the species. From 2014 to 2023, the distribution centroids of both mackerel species showed significant northward and eastward shifts, and their spatial overlap has been continuously increasing. This research provides a methodological reference for the fine-scale assessment of co-occurring fish resources and offers a scientific basis for the sustainable management of the North Pacific mackerel fishery. Full article

(This article belongs to the Special Issue Changes in Population Characteristics of Marine and Freshwater Organisms and Their Environmental Driving Factors)

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20 pages, 4833 KB

Open AccessArticle

Seasonal Spatial Distribution Characteristics and Patterns of the Squid Uroteuthis duvauceli, Uroteuthis edulis, Loliolus sumatrensis, and Loliolus japonica in the Southern Yellow and East China Seas: Predictions Under Different Climate Scenarios

by Min Xu, Hui Zhang, Bingqing Xu, Yong Liu and Linlin Yang

Animals 2025, 15(12), 1744; https://doi.org/10.3390/ani15121744 - 13 Jun 2025

Cited by 3 | Viewed by 1615

Abstract

For successful economic management of cephalopod fisheries, short-lived squid with a 1-year life span require stock assessment over a short timescale, accompanied by both in-season and real-time stock management. However, insufficient information is available about the dynamic distribution patterns of the squid Uroteuthis [...] Read more.

For successful economic management of cephalopod fisheries, short-lived squid with a 1-year life span require stock assessment over a short timescale, accompanied by both in-season and real-time stock management. However, insufficient information is available about the dynamic distribution patterns of the squid Uroteuthis duvauceli, Uroteuthis edulis, Loliolus sumatrensis, and Loliolus japonica in China. Such information is vital for establishing a sustainable fisheries management system. In this study, seasonal fishery-independent bottom-trawling surveys were performed from 2018 to 2019 in the southern Yellow and East China Seas to assess the seasonal changes in the distribution of these species. Most U. duvauceli occurred at sea bottom temperatures (SBTs) of 24.52–26.96 °C and sea bottom salinity (SBS) of 30.2–31.54‰ during the summer and at 20.02–22.75 °C and 33.46–34.22‰ during the autumn. Most U. edulis occurred at an SBT of 18.29–19.61 °C and SBS 34.78–35.08‰ during the spring, at 18.63–19.43 °C and 34.43–34.66‰ during the summer, at 8.78–21.81 °C and 34.39–34.77‰ during the autumn, and at 17.90–21.55 °C and 34.34–34.61‰ during the winter. Overall, most L. sumatrensis occurred at 21.00–23.15 °C and 34.11–34.50‰ in autumn. U. duvauceli concentrated in the fishing grounds of Zhoushan during the spring, Lvsi and Zhoushan-Changjiangkou during the summer, Zhoushan and Yushan-Mindong during the autumn, and Wentai-Yushan during the winter. L. sumatrensis mainly occurred in the fishing grounds of Dasha, Changjiangkou-Zhoushan, and Mindong during the summer, Yushan during the autumn, and nearshore areas during the winter. Most L. japonica occurred in the fishing grounds of Haizhou Bay and Zhoushan-Yushan during the spring, Haizhou Bay during the summer, Lvsi during the autumn, and Haizhou Bay during the winter. Our results will be useful for determining the total allowable catch from squid fisheries in these areas in China. Full article

(This article belongs to the Special Issue Changes in Population Characteristics of Marine and Freshwater Organisms and Their Environmental Driving Factors)

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20 pages, 2804 KB

Open AccessArticle

The Spatial Dynamics of Japanese Sardine (Sardinops sagax) Fishing Grounds in the Northwest Pacific: A Geostatistical Approach

by Yongzheng Tang, Yuanting Gong, Heng Zhang, Guoqing Zhao and Fenghua Tang

Animals 2025, 15(11), 1597; https://doi.org/10.3390/ani15111597 - 29 May 2025

Cited by 2 | Viewed by 2170

Abstract

The Japanese sardine (Sardinops sagax), a key economic species in the Northwest Pacific Ocean (NWPO), has shown significant increases in both population abundance and catch volume over the past decade. To understand its spatiotemporal dynamics under climate change, this study analyzed [...] Read more.

The Japanese sardine (Sardinops sagax), a key economic species in the Northwest Pacific Ocean (NWPO), has shown significant increases in both population abundance and catch volume over the past decade. To understand its spatiotemporal dynamics under climate change, this study analyzed light purse seine fishery data (2014–2021) from the NWPO. The results showed that the primary fishing season spans March to December, with peak catches concentrated in 40–43° N, 149–155° E. Annual catches grew steadily, accelerating notably in 2021. The fishing grounds’ center shifted northeastward annually and seasonally (southwest-to-northeast trajectory), driven by directional aggregation. Spatial clustering with global positive autocorrelation was observed, weakening as distance thresholds increased. Resource hotspots migrated northeast, narrowing from 40–42° N (2016) to 42–44° N (2017–2021), while coldspots showed complementary fluctuations. Generalized additive model (GAM) analysis revealed that the catch per unit effort (CPUE) of Japanese sardine in the high seas of the NWPO was governed by temporal–spatial drivers and multivariate environmental determinants. Analytical findings substantiate the significant climate-driven impacts on the spatiotemporal distribution and population dynamics of Japanese sardine. The non-stationary interannual and seasonal patterns of fishing grounds highlight the need for adaptive management strategies. Full article

(This article belongs to the Special Issue Changes in Population Characteristics of Marine and Freshwater Organisms and Their Environmental Driving Factors)

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14 pages, 1090 KB

Open AccessArticle

Insights into the Genetic Connectivity and Climate-Driven Northward Range Expansion of Turbo sazae (Gastropoda: Turbinidae) Along the Eastern Coast of Korea

by Young-Ghan Cho, Kyungman Kwon, Hyun Soo Rho, Won-Gi Min, Hee-Do Jeung, Un-Ki Hwang, Yong-Kyun Ryu, Areumi Park, Hyun-Ki Hong, Jong-Seop Shin and Hyun-Sung Yang

Animals 2025, 15(9), 1321; https://doi.org/10.3390/ani15091321 - 2 May 2025

Cited by 1 | Viewed by 1767

Abstract

Turbo sazae, a commercially and ecologically significant marine gastropod traditionally found in Jeju Island and the southern coast of Korea, is experiencing a reported northward expansion into the East Sea, likely influenced by rising seawater temperatures. This study provides preliminary genetic insights [...] Read more.

Turbo sazae, a commercially and ecologically significant marine gastropod traditionally found in Jeju Island and the southern coast of Korea, is experiencing a reported northward expansion into the East Sea, likely influenced by rising seawater temperatures. This study provides preliminary genetic insights into the genetic structure and connectivity of T. sazae populations between Jeju and the East Sea using mitochondrial COI sequences. Samples from 6 geographically distinct locations were analyzed, with three cloned replicates generated to enhance sequence reliability. Genetic diversity, haplotype distribution, and population differentiation were then assessed. Our analysis reveals potential genetic connectivity between Jeju and East Sea populations, possibly driven by larval dispersal via the Kuroshio and Tsushima Currents, highlighted by the predominance of shared haplotype EJ1 (60.0% in Jeju, 50.0% in East Sea). Bayesian phylogenetic analysis estimated the time to the most recent common ancestor (MRCA) between Jeju and East Sea populations at approximately 9.7 to 23.3 million years ago, indicating ancient divergence rather than very recent separation. Pairwise FST values and AMOVA results showed generally low levels of genetic differentiation. Given the small sample sizes and use of a single mitochondrial marker, these findings should be interpreted cautiously as preliminary evidence. Nevertheless, this study highlights the need for continued genetic monitoring of T. sazae populations under climate-driven range shifts and provides a foundation for future research incorporating broader genomic approaches. Full article

(This article belongs to the Special Issue Changes in Population Characteristics of Marine and Freshwater Organisms and Their Environmental Driving Factors)

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17 pages, 2783 KB

Open AccessArticle

The Spatio-Temporal Distribution and Population Dynamics of Chub Mackerel (Scomber japonicus) in the High Seas of the Northwest Pacific Ocean

by Guoqing Zhao, Heng Zhang and Fenghua Tang

Animals 2025, 15(8), 1135; https://doi.org/10.3390/ani15081135 - 15 Apr 2025

Cited by 1 | Viewed by 2333

Abstract

Chub mackerel (Scomber japonicus) is a typical small pelagic fish in the high seas of the Northwest Pacific Ocean (NPO), with great ecological and economic values. It is crucial to understand the spatio-temporal distribution and the population dynamics of chub mackerel for [...] Read more.

Chub mackerel (Scomber japonicus) is a typical small pelagic fish in the high seas of the Northwest Pacific Ocean (NPO), with great ecological and economic values. It is crucial to understand the spatio-temporal distribution and the population dynamics of chub mackerel for commercial fishing and fishery management. In this study, we analyzed the population dynamics and stock status of chub mackerel based on commercial fishing data. Results showed that from 2016 to 2021, high catches of chub mackerel were concentrated along the outer edge of Japan or Russia’s exclusive economic zone line, and the gravity center of the fishing grounds moved to the northwest gradually, with a decrease in the average value of catch per unit effort (CPUE) year by year. The fishing pressure may not be the major reason for the decrease in chub mackerel as the resource biomass was at a high level. The body length structure was reasonable, and large individuals were still present. The study highlights the fact that the population status of chub mackerel was healthy in 2016–2021 according to our results. However, it has to be emphasized that resource exploitation and fishery management also need to take into account the influence of climatic conditions. Full article

(This article belongs to the Special Issue Changes in Population Characteristics of Marine and Freshwater Organisms and Their Environmental Driving Factors)

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14 pages, 3614 KB

Open AccessArticle

Diel Vertical Migration and Transport Pattern of Larvae and Juveniles of the Small Yellow Croaker (Larimichthys polyactis) in the Yangtze River Estuary

by Xiaojing Song, Fen Hu, Jianzhong Ling, Xingwei Yuan, Zunlei Liu, Yan Jin, Shengfa Li and Yazhou Jiang

Animals 2025, 15(8), 1128; https://doi.org/10.3390/ani15081128 - 14 Apr 2025

Viewed by 1159

Abstract

In order to understand the diel vertical migration and transport pattern during their early life stages, the vertical distribution of larvae and juveniles of the small yellow croaker (Larimichthys polyactis) in the Yangtze River estuary was investigated. Four sampling cycles were [...] Read more.

In order to understand the diel vertical migration and transport pattern during their early life stages, the vertical distribution of larvae and juveniles of the small yellow croaker (Larimichthys polyactis) in the Yangtze River estuary was investigated. Four sampling cycles were carried out at the station (122°39′ E, 31° N) during May and June 2015. The samples were collected by vertically discrete plankton hauls in three strata of the water column: surface (0~2 m depth), middle (8~10 m depth), and bottom (18~20 m depth). The total number of small yellow croaker larvae was 5523, of which 65.2% and 25.8% were postflexion larvae and juveniles, respectively. Most of the individuals were collected in mid-May, and the sum of the quantity in May accounted for 94.8%. In all cruises, the highest abundance occurred at the bottom, while the surface maintained the lowest abundance. The flexion larvae, postflexion larvae and juveniles moved up to the surface and middle at night, but there was no significant difference between night and daytime for preflexion larvae in each stratum. The postflexion larvae and juveniles showed low temperature responses and a preference for the bottom habitat, respectively, while the preflexion and flexion larvae had weaker selectivity to the water layer and occurrence time. The abundance of larvae and juveniles in the middle layer was significantly higher at flood tide than at ebb tide, and it was more dominant at night than during the day. The study indicates that larvae and juveniles of the small yellow croaker change their located depth with diel vertical migration and utilize the faster speed of the mid-upper layer, which contributes to their ingress into the Yangtze River estuary nursery ground. Full article

(This article belongs to the Special Issue Changes in Population Characteristics of Marine and Freshwater Organisms and Their Environmental Driving Factors)

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21 pages, 5458 KB

Open AccessArticle

Cumulative Ecological Impact of Cascade Hydropower Development on Fish Community Structure in the Main Stream of the Xijiang River, China

by Yuansheng Zhu, Jiayang He, Fangyuan Xiong, Zhiqiang Wu, Jiajun Zhang, Yusen Li, Yong Lin, Anyou He, Dapeng Wang and Yaoquan Han

Animals 2025, 15(4), 495; https://doi.org/10.3390/ani15040495 - 10 Feb 2025

Cited by 3 | Viewed by 2894

Abstract

In recent decades, dams worldwide are increasingly constructed in a row along a single river or basin, thus forming reservoir cascades, and in turn producing cumulative ecological effects along these areas. The use of multimetric indices (MMI) based on fish assemblages to assess [...] Read more.

In recent decades, dams worldwide are increasingly constructed in a row along a single river or basin, thus forming reservoir cascades, and in turn producing cumulative ecological effects along these areas. The use of multimetric indices (MMI) based on fish assemblages to assess the ecological health status of rivers and lakes has also been extensively developed. However, to date, there are no studies that employ MMI for the identification of the cumulative effects of reservoir cascades. The aim of this study was to develop a new Fish-based Index of Biotic Integrity (F-IBI) that can effectively identify the cumulative effects of reservoir cascades on fish assemblages in two important habitats (the free-flowing reach between reservoirs and the transition zone in the reservoir). Fish assemblages from 12 sites were sampled along the cascade reservoirs in the Xijiang River, China. First, through screening for redundancy, precision, and responsiveness of the candidate metrics, a new F-IBI based on ecological trait information of fish species composition was developed to estimate the ecological status of all sites. F-IBI scores exhibited an obviously downward trend from upstream to downstream in a reservoir cascade, and the transition zones in the reservoir displayed significantly lower F-IBI scores than the free-flowing reaches between reservoirs. Secondly, using Random Forest models, it was shown that the F-IBI can effectively identify the cumulative effects of the reservoir cascades on fish assemblages. Furthermore, we also demonstrated metric-specific responses to different stressors, particularly the multiple reservoir cascades, which showed the following: (1) The F-IBI index system developed based on the Random Forest model can effectively identify the superimposed effects of cascade power stations on fish integrity changes, with the cumulative time effect and the GDP index of river segments playing a key role; (2) To effectively protect the fish resources in the main stream of the Xijiang River, where priority should be given to the habitat of the natural flowing river sections between the reservoirs. At the same time, environmental regulatory policies should be formulated accordingly based on the human development status of each river section. Full article

(This article belongs to the Special Issue Changes in Population Characteristics of Marine and Freshwater Organisms and Their Environmental Driving Factors)

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20 pages, 4075 KB

Open AccessArticle

Post-Fishing Ban Period: The Fish Diversity and Community Structure in the Poyang Lake Basin, Jiangxi Province, China

by Chiping Kong, Yulan Luo, Qun Xu, Bao Zhang, Xiaoping Gao, Xianyong Wang, Zhen Luo, Zhengli Luo, Lekang Li and Xiaoling Gong

Animals 2025, 15(3), 433; https://doi.org/10.3390/ani15030433 - 4 Feb 2025

Cited by 7 | Viewed by 3175

Abstract

Between 2022 and 2023, four systematic fish surveys were carried out in the Poyang Lake basin (PLB), capturing 49,192 fish (7017 kg) and identifying 120 species from 10 orders, 21 families, and 70 genera. Cypriniformes were the most dominant, accounting for 79 species. [...] Read more.

Between 2022 and 2023, four systematic fish surveys were carried out in the Poyang Lake basin (PLB), capturing 49,192 fish (7017 kg) and identifying 120 species from 10 orders, 21 families, and 70 genera. Cypriniformes were the most dominant, accounting for 79 species. The spring and autumn surveys collected 25,734 and 23,458 individuals, respectively, with corresponding biomasses of 3978 kg and 3038 kg. Dominant species (IRI > 1000) in the study area included Hemiculter leucisculus, Megalobrama skolkovii, Hypophthalmichthys molitrix, and Aristichthys nobilis. Additionally, critically endangered species such as Ochetobius elongatus, Myxocyprinus asiaticus, and Acipenser sinensis as well as exotic species like Cirrhinus mrigala and euryhaline species like Cynoglossus gracilis and Hyporhamphus intermedius were observed. Hierarchical clustering grouped the survey stations into three distinct areas (PYS, XBMS, and XBUS), with the ANOSIM analysis showing highly significant differences (R = 0.893, p < 0.01). Redundancy analysis (RDA) indicated that in spring, total phosphorus (TP) and temperature were the main factors influencing variability (80.50%), while in autumn, temperature, oil, and pH were the key factors (75.20%). This study emphasizes the predictable changes in fish community composition caused by environmental gradients and highlights the need for ongoing monitoring to effectively manage and protect the ecosystem, particularly in the post-fishing ban period. Full article

(This article belongs to the Special Issue Changes in Population Characteristics of Marine and Freshwater Organisms and Their Environmental Driving Factors)

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48 pages, 4979 KB

Open AccessArticle

Evaluating Ecosystem Characteristics and Ecological Carrying Capacity for Marine Fauna Stock Enhancement Within a Marine Ranching System

by Jie Feng, Haolin Yu, Lingjuan Wu, Chao Yuan, Xiaolong Zhao, Huiying Sun, Cheng Cheng, Yifei Li, Jingyi Sun, Yan Li, Xiaolong Wang, Yongjun Shang, Jiangling Xu and Tao Zhang

Animals 2025, 15(2), 165; https://doi.org/10.3390/ani15020165 - 10 Jan 2025

Cited by 5 | Viewed by 3371

Abstract

China has recently launched extensive marine ranching projects, highlighting the need for scientific evaluation of ecosystem structure and function to guide their development. This study established two energy flow models and an evaluation index system to assess the structure, function, carrying capacity, and [...] Read more.

China has recently launched extensive marine ranching projects, highlighting the need for scientific evaluation of ecosystem structure and function to guide their development. This study established two energy flow models and an evaluation index system to assess the structure, function, carrying capacity, and ecological status of both a marine ranching ecosystem and a nearby control site in the Beibu Gulf. The results show that the ranching ecosystem outperformed the control ecosystem in terms of food chain length, system size, and ecological carrying capacity of economically important species. The ranching ecosystem was classified as “relatively good”, while the control ecosystem was deemed “relatively poor”, which may confirm the success of the ranching efforts. Mussels, large crabs, and scorpaenidae were identified as key species for stock enhancement based on their biomass potential. Scenario simulations using Ecosim, driven by biomass and fishing factors, indicate that stock enhancement strategies targeting MOB (mussels, oysters, and barnacles) significantly improved the ranching ecosystem, raising its status to “good”. However, the simulations also revealed that stock enhancement had limited effects on optimizing food web structure, system organization, and energy transfer efficiency, suggesting that a combination of strategies is necessary for further improvement. Full article

(This article belongs to the Special Issue Changes in Population Characteristics of Marine and Freshwater Organisms and Their Environmental Driving Factors)

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14 pages, 3085 KB

Open AccessArticle

Long-Term Variations in Habitat Use of Humpback Dolphins Due to Anthropogenic Activities in Western Pearl River Estuary

by Xinxing Wang, Min Li, Liang Fang, Tao Chen and Wenhua Liu

Animals 2024, 14(23), 3381; https://doi.org/10.3390/ani14233381 - 24 Nov 2024

Cited by 6 | Viewed by 2204

Abstract

Marine mammals near coastlines are highly vulnerable to human activities like rapid industrialisation, port construction, and sea reclamation, which can alter their habitat use. This study examines changes in the habitat use of Indo-Pacific humpback dolphins in the western Pearl River Estuary (WPRE) [...] Read more.

Marine mammals near coastlines are highly vulnerable to human activities like rapid industrialisation, port construction, and sea reclamation, which can alter their habitat use. This study examines changes in the habitat use of Indo-Pacific humpback dolphins in the western Pearl River Estuary (WPRE) by employing a kernel density estimation model that considers physical barriers. Sighting records from systematic surveys in 2007–2008 and 2019–2020, along with remote sensing data, were used to analyse changes in shorelines and areas affected by maritime projects since 1973. Approximately 552.98 km² of water was permanently lost to reclamation between 1973 and 2020. In 2007–2008, dolphins preferred natural shorelines, while reclamation drove them away from artificial ones. By 2019–2020, their core habitat had decreased by two-thirds, with some areas disappearing, likely due to aquaculture expansion. These results highlight the importance of adopting improved environmental assessment methodologies in the planning and regulation of aquaculture activities in the WPRE to better protect the dolphin habitat. Full article

(This article belongs to the Special Issue Changes in Population Characteristics of Marine and Freshwater Organisms and Their Environmental Driving Factors)

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16 pages, 9215 KB

Open AccessArticle

Spatial Distribution and Growth Patterns of a Common Bivalve Mollusk (Macoma calcarea) in Svalbard Fjords in Relation to Environmental Factors

by Alyona E. Noskovich and Alexander G. Dvoretsky

Animals 2024, 14(23), 3352; https://doi.org/10.3390/ani14233352 - 21 Nov 2024

Cited by 4 | Viewed by 2019

Abstract

Ongoing warming in the Arctic has led to significant sea-ice loss and alterations in primary production, affecting all components of the marine food web. The considerable spatial variability of near-bottom environments around the Svalbard Archipelago renders the local fjords promising sites for revealing [...] Read more.

Ongoing warming in the Arctic has led to significant sea-ice loss and alterations in primary production, affecting all components of the marine food web. The considerable spatial variability of near-bottom environments around the Svalbard Archipelago renders the local fjords promising sites for revealing responses of benthic organisms to different environmental conditions. We investigated spatial variations in abundance, biomass, and growth parameters of the common bivalve Macoma calcarea in waters off western Spitsbergen and identified two distinct groups of this species: one composed mainly of cold-water stations from Storfjorden (Group I) and the other comprising warmer-water stations from Grønfjorden and Coles Bay (Group II). Within these groups, the mean abundance, biomass, production, and mortality accounted for 0.2 and 429 ind. m⁻², 20 and 179 g m⁻², 18.5 and 314 g m⁻² year⁻¹, and 0.22 and 0.10 year⁻¹ respectively. The size–frequency and age–frequency distributions were biased towards smaller and younger specimens in Group I, while Group II displayed more even distributions. The maximum ages were 11 and 21 years, respectively. The mollusks from cold water were significantly smaller than their same-aged counterparts from warmer water. Two groups of Macoma were identified: slow-growing individuals with a rate of 1.4 mm and fast-growing individuals with a growth rate of 1.8 mm. Most population parameters were higher than those observed in the Pechora, Kara, and Greenland Seas. Redundancy analysis indicated water temperature as the main driving factor of abundance and biomass, while the latter was also influenced by the presence of pebbles. Our findings provide new insights into the growth patterns and spatial distribution of Macoma at high latitudes and confirm that this species can serve as a reliable indicator of environmental conditions. Full article

(This article belongs to the Special Issue Changes in Population Characteristics of Marine and Freshwater Organisms and Their Environmental Driving Factors)

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