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Kongsfjorden is a small Arctic fjord but with great hydrographic complexity and has changed greatly due to the climate change. Arctic warming has increased melts of sea ice and glaciers that results in higher freshwater content. Microbial community variability and increasing terrestrial input were detected continuously in recent years ITag eukaryotic 18S rRNA V4 metabarcoding, photosynthetic pigments analysis and epifluorescence microscopy were used to reveal the dominant species of small eukaryotic community (<20 μm). Both Spearman correlation and redundant analysis were used to study the correlation between the small eukaryotes and the environmental conditions. In the present study, the surface water with salinity lower than 34 was thicker than in summers of previous years. The freshwater mixotrophic chrysophyte Poterioochromonas malhamensis was found for the first time as the dominant species. No general trends were found for the contributions of P. malhamensis to the total reads of small eukaryotes in water depths; and no obvious differences were found at different stations and water masses. Phagotrophy, which is more common than phototrophy at all times in P. malhamensis, is thought to be the main reason for the prevalence of P. malhamensis in Kongsfjorden. The occurrence of P. malhamensis induced a disorder in the small eukaryotic community, which biodiversity and composition showed weak correlation with the water masses. The dominance of the freshwater-originating phytoplankton may indicate an ecosystem change in the Kongsjforden, which probably might become more remarkable in the future as the climate continues to change.
Fang Zhang; Yongjun Tian; Jianfeng He. Occurrence of the Freshwater Chrysophyte Poterioochromonas malhamensis in a High Arctic Marine Ecosystem. Water 2021, 13, 2129 .
AMA StyleFang Zhang, Yongjun Tian, Jianfeng He. Occurrence of the Freshwater Chrysophyte Poterioochromonas malhamensis in a High Arctic Marine Ecosystem. Water. 2021; 13 (15):2129.
Chicago/Turabian StyleFang Zhang; Yongjun Tian; Jianfeng He. 2021. "Occurrence of the Freshwater Chrysophyte Poterioochromonas malhamensis in a High Arctic Marine Ecosystem." Water 13, no. 15: 2129.
The Yellow Sea is the southern limit of the distribution of Pacific cod (Gadus microcephalus), and the Yellow Sea Cold Water Mass (YSCWM) provides an appropriate over-summering habitat for this species. Tidal current is the major component of the Yellow Sea hydrodynamic system, and its periodic variations influence the local ecological conditions and related ecosystems, particularly in the YSCWM, which is stratified in summer. To investigate the influence of tidal currents on Pacific cod growth, otolith daily increment in young-of-the-year (YOY) Pacific cod in the Yellow Sea was analyzed in 2017. These data were integrated with a simulated tidal current using a multi-scenario time-delay analysis. This showed that: (1) the otolith daily increment exhibited a strong signal similar to the fortnightly tidal variation; (2) there was a lag of ∼8 days between the highest growth rate induced by the tidal current variation and monthly spring tide; and (3) the influence of the tidal current on otolith daily growth was stronger after migration of the cod into the YSCWM, particularly during the settlement stage. Given the stratified ocean structure during the over-summering period, enhanced tidal mixing during the fortnightly spring tide would improve the exchange of nutrients and oxygen within the YSCWM, and lead to a delayed response of otolith growth due to feeding/digestion and subsequent growth. Therefore, variations in the tidal current have a marked positive ecological effect on the growth of YOY Pacific cod, and ultimately on the YSCWM ecosystem.
Jianchao Li; Feng Jiang; Rui Wu; Chi Zhang; Yongjun Tian; Peng Sun; Haiqing Yu; Yang Liu; Zhenjiang Ye; Shuyang Ma; Shude Liu; Xiuqiang Dong. Tidally Induced Temporal Variations in Growth of Young‐of‐the‐Year Pacific Cod in the Yellow Sea. Journal of Geophysical Research: Oceans 2021, 126, 1 .
AMA StyleJianchao Li, Feng Jiang, Rui Wu, Chi Zhang, Yongjun Tian, Peng Sun, Haiqing Yu, Yang Liu, Zhenjiang Ye, Shuyang Ma, Shude Liu, Xiuqiang Dong. Tidally Induced Temporal Variations in Growth of Young‐of‐the‐Year Pacific Cod in the Yellow Sea. Journal of Geophysical Research: Oceans. 2021; 126 (6):1.
Chicago/Turabian StyleJianchao Li; Feng Jiang; Rui Wu; Chi Zhang; Yongjun Tian; Peng Sun; Haiqing Yu; Yang Liu; Zhenjiang Ye; Shuyang Ma; Shude Liu; Xiuqiang Dong. 2021. "Tidally Induced Temporal Variations in Growth of Young‐of‐the‐Year Pacific Cod in the Yellow Sea." Journal of Geophysical Research: Oceans 126, no. 6: 1.
The Yellow Sea is the southwestern limit of the distribution of Pacific cod (Gadus macrocephalus), a typical cold water and commercially important fish in the North Pacific. The catch of Pacific cod in the Yellow Sea has increased gradually in recent years, and has received substantial attention. To explore the use of otolith chemistry in the characterization of different spawning grounds and crucial life history events, a total of 60 specimens of Pacific cod were obtained from October 2016 to August 2017. The contents of barium (Ba) and strontium (Sr) in otoliths from the core to the edge along the ventral side were determined using laser ablation-inductively coupled plasma-mass spectrometry. Based on hierarchical cluster analysis (HCA), the specimens were assigned to two groups based on the ratio of Ba:Ca at the core. The various patterns of core-to-edge Ba:Ca inferred using a linear mixed-effect (LMM) model suggested differences in the spawning ground environments for Pacific cod in the Yellow Sea, and step changes found in the Sr:Ca ratio, and a corresponding check observed in otolith images suggest that the settlement of Pacific cod occurred approximately 80–120 days after hatching. The nature of the data prevents firm conclusions being drawn from the data available at present, but the significant differences in certain elements among individuals and the association with crucial life history events in Pacific cod are noteworthy.
Rui Wu; Jianchao Li; Chi Zhang; Xindong Pan; Tao Jiang; Jian Yang; Shude Liu; Yongjun Tian. Fine-scale variability in otolith chemistry: Application to the life history analysis of Pacific cod (Gadus macrocephalus) in the Yellow Sea. Estuarine, Coastal and Shelf Science 2021, 257, 107392 .
AMA StyleRui Wu, Jianchao Li, Chi Zhang, Xindong Pan, Tao Jiang, Jian Yang, Shude Liu, Yongjun Tian. Fine-scale variability in otolith chemistry: Application to the life history analysis of Pacific cod (Gadus macrocephalus) in the Yellow Sea. Estuarine, Coastal and Shelf Science. 2021; 257 ():107392.
Chicago/Turabian StyleRui Wu; Jianchao Li; Chi Zhang; Xindong Pan; Tao Jiang; Jian Yang; Shude Liu; Yongjun Tian. 2021. "Fine-scale variability in otolith chemistry: Application to the life history analysis of Pacific cod (Gadus macrocephalus) in the Yellow Sea." Estuarine, Coastal and Shelf Science 257, no. : 107392.
Chub mackerel (Scomber japonicus) in the northwest Pacific Ocean is generally divided into the Tsushima Warm Current (TWC) and Pacific stocks, based on habitat and migratory patterns. Since the 1970s, the abundance of the Pacific stock has undergone more extreme fluctuations than the TWC stock, which decreased sharply in the late 1970s and remained at low levels until it began to recover after the 2000s. In this study we focused on the Pacific stock, and analysed the variability in its abundance based on time series data for catch, biomass and recruitment. Sea surface temperature is considered as a major environmental factor that affects the wintering and spawning of chub mackerel. Consequently, we used wintering and spawning ground indices, including the average sea surface temperature (SST), the meridional positional deviance of the 15 °C (MPD15) and 18 °C (MPD18) isotherms and the SST-suitability weighted size of the potential spawning ground (WSSG) in Kuroshio Current waters to analyse the impacts of oceanic environmental conditions in the wintering and spawning grounds on variations in chub mackerel abundance. The wintering and spawning ground indices showed clear decadal variability, with abrupt changes in the late 1970s, the late 1980s and the 2010s. These were correlated with major fluctuations in the abundance of chub mackerel. A combination of correlation and gradient forest analyses showed that the thermal environment in the wintering ground were relatively important predictors of chub mackerel abundance; these predictors (with a 1- or 2-year time lag) may better explain the variations in abundance after the 1970s. Variations in the SST and MPD18 during the spawning period correlated well with the recovery of chub mackerel abundance after the 2000s. Both the Asian Monsoon Index and Southern Oscillation Index correlated with the wintering and spawning ground temperature conditions, indicating that large scale climatic factors have a major influence on variability in temperature in the wintering and spawning grounds of chub mackerel. We conclude that wintering and spawning ground indices for the Kuroshio Current region may be useful for explaining the variations in chub mackerel abundance.
Liangming Wang; Shuyang Ma; Yang Liu; Jianchao Li; Shigang Liu; Longshan Lin; Yongjun Tian. Fluctuations in the abundance of chub mackerel in relation to climatic/oceanic regime shifts in the northwest Pacific Ocean since the 1970s. Journal of Marine Systems 2021, 218, 103541 .
AMA StyleLiangming Wang, Shuyang Ma, Yang Liu, Jianchao Li, Shigang Liu, Longshan Lin, Yongjun Tian. Fluctuations in the abundance of chub mackerel in relation to climatic/oceanic regime shifts in the northwest Pacific Ocean since the 1970s. Journal of Marine Systems. 2021; 218 ():103541.
Chicago/Turabian StyleLiangming Wang; Shuyang Ma; Yang Liu; Jianchao Li; Shigang Liu; Longshan Lin; Yongjun Tian. 2021. "Fluctuations in the abundance of chub mackerel in relation to climatic/oceanic regime shifts in the northwest Pacific Ocean since the 1970s." Journal of Marine Systems 218, no. : 103541.
The Pacific saury Cololabis saira is a commercially important pelagic species with wide distribution in the North Pacific Ocean. Previous studies identified two geographical groups by comparing the radius of otolith annual rings (ROA) of the fish collected during the pre-fishing season. Moreover, understanding the group composition in the mixed catch from the fishing ground is essential for sustainable exploitation of this species. Using samples collected during the fishing season (July-November) from 2016 to 2018, the potential of applying otolith shape analysis as a tool to identify these two mixed groups was tested in this research. Two otolith morphotypes that belong to the eastern group and western group were identified by K-means cluster analysis using Fourier coefficients and ROA. The high classification success of random forest further confirmed the effectiveness of otolith shape analysis. The western group accounted for the majority of catch in July and August at 160°E. With the passing of sampling time and fishing fleets moving westward, the proportion of eastern group gradually increased and finally reached more than 60% of the whole catch in November at 150°E. This result suggests that the eastern and western groups are well mixed during spawning migration. In addition, the temporal and spatial dynamics of their catch composition provide information for their migration route. This study is helpful for improving fisheries management and understanding the short-term stock fluctuation of Pacific saury.
Wenjia Li; Chi Zhang; Yongjun Tian; Yang Liu; Shigang Liu; Hao Tian; Chang Cao. Otolith Shape Analysis as a Tool to Identify Two Pacific Saury (Cololabis saira) Groups from a Mixed Stock in the High-Seas Fishing Ground. Journal of Ocean University of China 2021, 20, 402 -408.
AMA StyleWenjia Li, Chi Zhang, Yongjun Tian, Yang Liu, Shigang Liu, Hao Tian, Chang Cao. Otolith Shape Analysis as a Tool to Identify Two Pacific Saury (Cololabis saira) Groups from a Mixed Stock in the High-Seas Fishing Ground. Journal of Ocean University of China. 2021; 20 (2):402-408.
Chicago/Turabian StyleWenjia Li; Chi Zhang; Yongjun Tian; Yang Liu; Shigang Liu; Hao Tian; Chang Cao. 2021. "Otolith Shape Analysis as a Tool to Identify Two Pacific Saury (Cololabis saira) Groups from a Mixed Stock in the High-Seas Fishing Ground." Journal of Ocean University of China 20, no. 2: 402-408.
Increasing evidence has suggested that climate variability has a vital impact on the stock fluctuation of many small pelagic fishes by regulating their recruitment. However, most recruitment-related studies have focused on large spawning/nursing grounds at annual or seasonal scales, while few have considered the impact of short-term environmental variations during the vulnerable passive-transport period. In this study, a larval growth index based on a Lagrangian particle-tracking model coupled with a hydrodynamic model that focused on the early growth and passive transport of the SPF was developed to identify the key spawning/nursing period and grounds accommodating fish recruitment. Taking Japanese anchovy (Engraulis japonicus) in the Yellow Sea as an example, the key spawning grounds and time for its recruitment was identified and the impact of sea-surface temperature (SST) and climate variability on its recruitment was then investigated and discussed. Significant positive (negative) correlations were identified between the recruitment index and the mean growth index (mean water temperature) along the tracking path of eggs or larvae released in the Bohai Sea and the southwestern Yellow Sea during July (1987–2004), implying that these were the key spawning grounds and period for recruitment success. The multi-year tracking path of released particles indicated that both the southwestern Yellow Sea and the central Bohai Sea may be the key nursing grounds. Meanwhile, the SST in July was found to be associated with basin-scale atmosphere–ocean interactions. A potential “atmosphere–ocean-recruitment” influence pattern for Japanese anchovy in the Yellow and Bohai Seas was thus proposed, in which higher (lower) temperature during the key spawning/nursing period induced by atmospheric variation might diminish (promote) recruitment success by limiting the growth and survival of anchovy larvae. The larval growth index developed in this study can be widely applied to other small pelagic fishes in other waters and provide implications for climate-induced recruitment studies.
Qinwang Xing; Haiqing Yu; Shin-Ichi Ito; Shuyang Ma; Huaming Yu; Hui Wang; Yongjun Tian; Peng Sun; Yang Liu; Jianchao Li; Zhenjiang Ye. Using a larval growth index to detect the environment-recruitment relationships and its linkage with basin-scale climate variability: A case study for Japanese anchovy (Engraulis japonicus) in the Yellow Sea. Ecological Indicators 2020, 122, 107301 .
AMA StyleQinwang Xing, Haiqing Yu, Shin-Ichi Ito, Shuyang Ma, Huaming Yu, Hui Wang, Yongjun Tian, Peng Sun, Yang Liu, Jianchao Li, Zhenjiang Ye. Using a larval growth index to detect the environment-recruitment relationships and its linkage with basin-scale climate variability: A case study for Japanese anchovy (Engraulis japonicus) in the Yellow Sea. Ecological Indicators. 2020; 122 ():107301.
Chicago/Turabian StyleQinwang Xing; Haiqing Yu; Shin-Ichi Ito; Shuyang Ma; Huaming Yu; Hui Wang; Yongjun Tian; Peng Sun; Yang Liu; Jianchao Li; Zhenjiang Ye. 2020. "Using a larval growth index to detect the environment-recruitment relationships and its linkage with basin-scale climate variability: A case study for Japanese anchovy (Engraulis japonicus) in the Yellow Sea." Ecological Indicators 122, no. : 107301.
The green mussel (Perna viridis) is one of the most commercially-important cultured species along the coast of Thailand. In this study, a suitable aquaculture site-selection model (SASSM) was developed to identify the most suitable areas in the inner part of the Gulf of Thailand (InnerGoT) for green mussel culture. Satellite-derived chlorophyll-a (Chl-a) and hydrodynamic model outputs for sea surface temperature (SST), salinity, maximum water current (MWC), and bathymetry between 2018 and 2019 were used as input to the SASSM. The results show that suitability scores in mussel aquaculture areas were lowest (1–3) during the Southwest (SW) monsoon, rainy season (July–August), and highest (6–7) during the Northeast (NE) monsoon, cold season (November–December). Moderate suitability scores (4–5) were obtained during the monsoon transition from the NE monsoon to the SW monsoon, summer (April–May). The study area was further divided into three zones: the western, central, and eastern regions. The western and eastern parts showed high suitability scores (5–7) while the central zone exhibited low suitability scores (2–4). The model results show a similar pattern to the actual mussel production in the study area. Seasonal events (i.e., flood and dry seasons) were incorporated into the model to examine the seasonal effects on the suitable mussel aquaculture areas. The suitability scores during the SW monsoon in 2018 were more sensitive to changes in SST and salinity relative to 2019. The higher freshwater discharge and lower temperature in 2018 relative to 2019 resulted in the accrual of suitable aquaculture areas. This pattern is consistent with the productions of the green mussel, where higher production was recorded in 2018 (2002.5 t) than in 2019 (410.8 t). However, correlations among atmospheric (air temperature, rainfall, and wind) and oceanographic factors (SST and MWC) were significant in the western and central regions, suggesting that the suitability of green mussel aquaculture in these regions is vulnerable to environmental disturbances. Thus, the SASSM can be a powerful tool in providing useful information on spatial management for marine aquaculture in environmentally-dynamic coastal systems.
Hathaichanok Kumgumpol; Yang Liu; Tanuspong Pokavanich; Irene Alabia; Zixu Yin; Sei-Ichi Saitoh; Yongjun Tian. Environmental Habitat Mapping of Green Mussel: A GIS-Based Approach for Sustainable Aquaculture in the Inner Gulf of Thailand. Sustainability 2020, 12, 10643 .
AMA StyleHathaichanok Kumgumpol, Yang Liu, Tanuspong Pokavanich, Irene Alabia, Zixu Yin, Sei-Ichi Saitoh, Yongjun Tian. Environmental Habitat Mapping of Green Mussel: A GIS-Based Approach for Sustainable Aquaculture in the Inner Gulf of Thailand. Sustainability. 2020; 12 (24):10643.
Chicago/Turabian StyleHathaichanok Kumgumpol; Yang Liu; Tanuspong Pokavanich; Irene Alabia; Zixu Yin; Sei-Ichi Saitoh; Yongjun Tian. 2020. "Environmental Habitat Mapping of Green Mussel: A GIS-Based Approach for Sustainable Aquaculture in the Inner Gulf of Thailand." Sustainability 12, no. 24: 10643.
Japanese Spanish mackerel, Scomberomorus niphonius, is a commercially important, highly migratory species that is widely distributed throughout the northwestern Pacific region. However, its life history and migratory patterns are only partially understood. This study used otolith chemistry to investigate the migratory pattern of S. niphonius in the southern Yellow Sea, an important fishing ground. Transverse sections of otoliths from 15 age-1 spawning or spent individuals, comprising up to one complete migration cycle, were analyzed from the core to the margin by using laser ablation inductively coupled plasma mass spectrometry. The ratios of the element to Ca were integrated with microstructural analysis to produce age-related elemental profiles. Combining multielemental analysis of otolith composition with multivariate analytical models, we quantified structural changes in otolith chemistry profiles. Results revealed there were diverse changing patterns of otolith chemistry profiles for detected elements and the elements of Na, Mg, Sr and Ba were important for the chronological signal. Five clusters were identified through chronological clustering, representing the five life stages from the early stage to the spawning stage. Variation of Ba:Ca ratio was most informative, showing a step-decreasing pattern in the first four stages and a rebound in the spawning stage. These results support the hypothesized migratory pattern of S. niphonius: hatching and spending their early life in the coastal sandy ridges system of the southern Yellow Sea, migrating northeastward and offshore for feeding during juvenile stage, aggregating in early October and migrating outward to the Jeju Island for wintering, and returning to the coastal waters for spawning. This study demonstrated the value of life-history related otolith chemistry profiles combined with multivariate analytical models was a means to verify the migration patterns of S. niphonius at regional scales with potential application in fisheries assessment and management.
Xindong Pan; Zhenjiang Ye; Binduo Xu; Tao Jiang; Jian Yang; Jiahua Cheng; Yongjun Tian. Combining otolith elemental signatures with multivariate analytical models to verify the migratory pattern of Japanese Spanish mackerel (Scomberomorus niphonius) in the southern Yellow Sea. Acta Oceanologica Sinica 2020, 39, 54 -64.
AMA StyleXindong Pan, Zhenjiang Ye, Binduo Xu, Tao Jiang, Jian Yang, Jiahua Cheng, Yongjun Tian. Combining otolith elemental signatures with multivariate analytical models to verify the migratory pattern of Japanese Spanish mackerel (Scomberomorus niphonius) in the southern Yellow Sea. Acta Oceanologica Sinica. 2020; 39 (12):54-64.
Chicago/Turabian StyleXindong Pan; Zhenjiang Ye; Binduo Xu; Tao Jiang; Jian Yang; Jiahua Cheng; Yongjun Tian. 2020. "Combining otolith elemental signatures with multivariate analytical models to verify the migratory pattern of Japanese Spanish mackerel (Scomberomorus niphonius) in the southern Yellow Sea." Acta Oceanologica Sinica 39, no. 12: 54-64.
Identification of squids in the family Loliginidae is a time-consuming exercise because of the highly overlapping distributions of species and their overall similarity (fin shape and size, sucker ring dentition, and color). Identifying squid based on statolith morphology is considered more accurate than identifying species based on beaks or gladius morphology. We report and compare the statolith shape of five commercially Loliginidae squid (Uroteuthis (Photololigo) duvaucelii, U. edulis, U. chinensis, Loliolus beka, L. japonica) to determine how well these structures discriminate species. Based on statolith morphology, variation in the lateral and dorsal domes enables an 84.8% success rate at classifying species. Environmental factors correlate with statolith shape, and for vertically migrating squid, statolith relative size decreases with increased depth of habitation. Statolith morphology can be used to effectively and accurately identify species of Loliginidae squid occurring in Chinese waters, and may prove valuable for identifying and managing squid resources.
Jianzhong Guo; Dan Liu; Chi Zhang; Yongjun Tian; Zhixin Li. Using statolith shape analysis to identify five commercial Loliginidae squid species in Chinese waters. Journal of Oceanology and Limnology 2020, 39, 1160 -1167.
AMA StyleJianzhong Guo, Dan Liu, Chi Zhang, Yongjun Tian, Zhixin Li. Using statolith shape analysis to identify five commercial Loliginidae squid species in Chinese waters. Journal of Oceanology and Limnology. 2020; 39 (3):1160-1167.
Chicago/Turabian StyleJianzhong Guo; Dan Liu; Chi Zhang; Yongjun Tian; Zhixin Li. 2020. "Using statolith shape analysis to identify five commercial Loliginidae squid species in Chinese waters." Journal of Oceanology and Limnology 39, no. 3: 1160-1167.
Octopus fisheries have prospered in many areas of the world ocean over the last six decades. Despite degradation and overexploitation of Chinese coastal ecosystems, octopus has become a stable Chinese domestic fishery species. Among the octopus species in the Bohai and Yellow, East and South China Seas, Amphioctopus fangsiao (d’Orbigny [in Férussac & d’Orbigny], 1839–1841) plays an increasingly important role both economically and ecologically. However, no systematic research has been conducted on its biology and population dynamics in the China Seas. In this study, we characterized the growth and distribution of A. fangsiao in Haizhou Bay, Yellow Sea based on four years of trawl survey data. As the results, A. fangsiao is characterized by allometric growth and an overall sex ratio of 0.97 with a slight male bias. Small octopus can be observed through a whole year, suggesting that A. fangsiao may have an extended or continuous spawning season. A. fangsiao may migrate short distances along with seasonal changes and coastal currents, considering they overwinter in the offshore water and spawn in the inshore water. In addition to fishing pressure, annual variations in the population structure and biomass appeared to be influenced by ambient water temperature. These results provide basic biological information for a better understanding of the population dynamics and the ecological importance of A. fangsiao.
Yumeng Pang; Yongjun Tian; Caihong Fu; Yiping Ren; Rong Wan. Growth and Distribution of Amphioctopus fangsiao (d’Orbigny, 1839–1841) in Haizhou Bay, Yellow Sea. Journal of Ocean University of China 2020, 19, 1125 -1132.
AMA StyleYumeng Pang, Yongjun Tian, Caihong Fu, Yiping Ren, Rong Wan. Growth and Distribution of Amphioctopus fangsiao (d’Orbigny, 1839–1841) in Haizhou Bay, Yellow Sea. Journal of Ocean University of China. 2020; 19 (5):1125-1132.
Chicago/Turabian StyleYumeng Pang; Yongjun Tian; Caihong Fu; Yiping Ren; Rong Wan. 2020. "Growth and Distribution of Amphioctopus fangsiao (d’Orbigny, 1839–1841) in Haizhou Bay, Yellow Sea." Journal of Ocean University of China 19, no. 5: 1125-1132.
Water temperature and food availability are two environmental factors that are widely considered to be likely determinants of recruitment success of fish stocks. However, marine environmental data are commonly of limited availability. Moreover, the mechanisms by which environmental variations may act to regulate fish recruitment remain incompletely understood, especially from the point of view of prey availability. Here we report a test of the feasibility of using simulated long-term hindcast of marine environmental data based on a physical and lower-trophic-level ecosystem data-assimilative model to investigate the impacts of water temperature and prey availability on recruitment fluctuations of the Japanese anchovy (Engraulis japonicus) in the Yellow Sea. Although observational data available for model validation were limited, the model reasonably reproduced inter-annual fluctuations of phytoplankton abundance. The model results for a 15-year period (1987–2001) indicated Japanese anchovy recruitment to have been negatively correlated with July sea surface temperature in the traditional spawning ground south of the Shandong Peninsula, while being positively correlated with near-surface biomass of small zooplankton (the predominant prey for anchovy larvae) in the central Yellow Sea during the summer period. These findings imply that the Japanese anchovy recruitment in the Yellow Sea is likely regulated during its early life stages by both water temperature and food availability. The negative temperature-recruitment relationship could be explained by the “spawning temperature optima” and “optimal growth temperature” hypotheses. Furthermore, model results indicated that inter-annual variation in the near-surface biomass of small zooplankton in the central Yellow Sea during summer is mainly regulated by nutrient supply, to which both vertical stratification and horizontal advection may make contributions.
Haiqing Yu; Huaming Yu; Shin-Ichi Ito; Yongjun Tian; Hui Wang; Yang Liu; Qinwang Xing; Andrew Bakun; Ryan M. Kelly. Potential environmental drivers of Japanese anchovy (Engraulis japonicus) recruitment in the Yellow Sea. Journal of Marine Systems 2020, 212, 103431 .
AMA StyleHaiqing Yu, Huaming Yu, Shin-Ichi Ito, Yongjun Tian, Hui Wang, Yang Liu, Qinwang Xing, Andrew Bakun, Ryan M. Kelly. Potential environmental drivers of Japanese anchovy (Engraulis japonicus) recruitment in the Yellow Sea. Journal of Marine Systems. 2020; 212 ():103431.
Chicago/Turabian StyleHaiqing Yu; Huaming Yu; Shin-Ichi Ito; Yongjun Tian; Hui Wang; Yang Liu; Qinwang Xing; Andrew Bakun; Ryan M. Kelly. 2020. "Potential environmental drivers of Japanese anchovy (Engraulis japonicus) recruitment in the Yellow Sea." Journal of Marine Systems 212, no. : 103431.
Largehead hairtail (Trichiurus japonicus ) in the China Seas shows an increasing catch trend, despite continued overexploitation, which could be attributed to improved recruitment as a result of strengthened early growth. To understand the early growth variability of largehead hairtail, we examined the linkages between early growth, as revealed by otolith microstructure, and the associated environmental variables over both spatial and temporal scales. Young‐of‐the‐Year largehead hairtail were collected from three regions in the Bohai, Yellow and East China Seas between 29° and 39° N. Daily increment widths of sagittal otoliths were measured and used as a proxy for somatic growth. We found two spawning cohorts, Spring‐ and Summer‐spawned cohorts, that showed latitudinal differences in both mean growth and growth pattern. The transition time from larval to juvenile stage was identified at around 40 days. Daily increment widths of two cohorts showed similar growth pattern in the first 40 days, while location had a marked effect on daily growth over 41–110 days. This suggests physiologically constrained growth pattern in larval stage, but more plastic growth subject to habitat‐specific influences in juvenile stage. The gradient forest analysis identified sea bottom temperature, vertical temperature gradient, and sea surface salinity, as the most important variables in determining early growth. Latitudinal differences in early growth pattern and their response to environmental variables suggest adaptive plasticity of early growth, which has notable implication for the management and sustainable utilization of this important but heavily exploited resource in the China Seas.
Peng Sun; Qi Chen; Caihong Fu; Yi Xu; Runlong Sun; Jianchao Li; Haiqing Yu; Chi Zhang; Yang Liu; Zhenjiang Ye; Yongjun Tian; Mikko Heino. Latitudinal differences in early growth of largehead hairtail ( Trichiurus japonicus ) in relation to environmental variables. Fisheries Oceanography 2020, 29, 470 -483.
AMA StylePeng Sun, Qi Chen, Caihong Fu, Yi Xu, Runlong Sun, Jianchao Li, Haiqing Yu, Chi Zhang, Yang Liu, Zhenjiang Ye, Yongjun Tian, Mikko Heino. Latitudinal differences in early growth of largehead hairtail ( Trichiurus japonicus ) in relation to environmental variables. Fisheries Oceanography. 2020; 29 (6):470-483.
Chicago/Turabian StylePeng Sun; Qi Chen; Caihong Fu; Yi Xu; Runlong Sun; Jianchao Li; Haiqing Yu; Chi Zhang; Yang Liu; Zhenjiang Ye; Yongjun Tian; Mikko Heino. 2020. "Latitudinal differences in early growth of largehead hairtail ( Trichiurus japonicus ) in relation to environmental variables." Fisheries Oceanography 29, no. 6: 470-483.
Connectivity is a vital component of metapopulation and fishery ecology, influencing fundamental processes such as population dynamics, evolution, and community responses to climate change. The Japanese Spanish mackerel, Scomberomorus niphonius, is an economically important species in the temperate and subtropical waters of the Northwestern Pacific Ocean, especially in the China seas. As a highly migratory species, the population connectivity of S. niphonius is not only limited to dispersal in the pelagic larval stage but throughout the whole life history, and then determines the natal origin and population structure. However, knowledge about population connectivity is scarce and, at present, is no formal management strategy to ensure the long-term sustainability of the S. niphonius fishery in China. In this study, otolith chemistry was applied to investigate the connectivity among four spawning grounds along a latitudinal gradient spanning much of the known species range in the Yellow Sea and the East China Sea [Qingdao (QD), Lvsi (LS), Xiangshan (XS) and Fuzhou (FZ)]. Otoliths from age-1 spawning or spent individuals were analyzed from the core to the margin by using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). In each sampled life stage, otolith elements are similar among fish from different spawning grounds, but otolith chemical compositions vary greatly between life stages. Decreasing Ba:Ca ratio indicates ontogenetic migrations from relatively shallow coastal water during larval growth to relatively deep offshore waters with increasing age. The random forest classification and non-metric multi-dimensional scaling show a strong overlap in otolith elemental composition. The hereby results indicate a large-scale connectivity in the life history of S. niphonius: the immature fish mix to a large extent when they feed and overwinter in the extensive offshore waters; adults spawned in the same spawning ground have multiple natal origins and fish caught off QD may even be of FZ origin. Clustering of near core chemistry pointed to three sources, with southern grounds dominated by a single cluster while northern grounds dominated by two or three clusters. From these results, it was suggested that the local mackerel assemblages on which fisheries rely in the Yellow Sea are collectively influenced by the recruitment of all the spawning assemblages along China coastal waters instead of self-sustaining.
Xindong Pan; Zhenjiang Ye; Binduo Xu; Tao Jiang; Jian Yang; Yongjun Tian. Population connectivity in a highly migratory fish, Japanese Spanish mackerel (Scomberomorus niphonius), along the Chinese coast, implications from otolith chemistry. Fisheries Research 2020, 231, 105690 .
AMA StyleXindong Pan, Zhenjiang Ye, Binduo Xu, Tao Jiang, Jian Yang, Yongjun Tian. Population connectivity in a highly migratory fish, Japanese Spanish mackerel (Scomberomorus niphonius), along the Chinese coast, implications from otolith chemistry. Fisheries Research. 2020; 231 ():105690.
Chicago/Turabian StyleXindong Pan; Zhenjiang Ye; Binduo Xu; Tao Jiang; Jian Yang; Yongjun Tian. 2020. "Population connectivity in a highly migratory fish, Japanese Spanish mackerel (Scomberomorus niphonius), along the Chinese coast, implications from otolith chemistry." Fisheries Research 231, no. : 105690.
Larval retention has been recognized as a key factor/process affecting the recruitment of many pelagic fish species and detection of the larval retention areas (LRAs) is thus of crucial importance for studies of both recruitment dynamics and of fisheries management. However, most studies in relation to larval retention have adopted either retention rate or time to represent retention level. In this study, a newly developed approach based on a Lagrangian particle-tracking algorithm coupled with a hydrodynamic model, thereby jointly considering both retention rate and time to quantify larvae retention level, was introduced and used to identify the prominent LRAs for Japanese anchovy Engraulis japonicus in the Yellow Sea. Four prominent LRAs were identified, two of which locating in the Southern Yellow Sea match well with the aggregation of Japanese anchovy larvae found in previous field surveys. The spatial–temporal variation of instantaneous retention rate was further analyzed and the contribution rates of spawning grounds to LRAs as well as sensitivity of pelagic larval duration to the LRAs were investigated. Meanwhile, the LRAs defined in this study can be also used to explain the aggregations of microzooplankton and green algae in the southern part of the Yellow Sea. This approach can be widely applied to other pelagic species during their planktonic stages, which may further provide implications for studies on recruitment dynamics and on marine protected areas (MPAs) in the Yellow Sea as well as in other continental shelf regions containing abundant fishery resources.
Qinwang Xing; Huaming Yu; Haiqing Yu; Peng Sun; Yang Liu; Zhenjiang Ye; Jianchao Li; Yongjun Tian. A comprehensive model-based index for identification of larval retention areas: A case study for Japanese anchovy Engraulis japonicus in the Yellow Sea. Ecological Indicators 2020, 116, 106479 .
AMA StyleQinwang Xing, Huaming Yu, Haiqing Yu, Peng Sun, Yang Liu, Zhenjiang Ye, Jianchao Li, Yongjun Tian. A comprehensive model-based index for identification of larval retention areas: A case study for Japanese anchovy Engraulis japonicus in the Yellow Sea. Ecological Indicators. 2020; 116 ():106479.
Chicago/Turabian StyleQinwang Xing; Huaming Yu; Haiqing Yu; Peng Sun; Yang Liu; Zhenjiang Ye; Jianchao Li; Yongjun Tian. 2020. "A comprehensive model-based index for identification of larval retention areas: A case study for Japanese anchovy Engraulis japonicus in the Yellow Sea." Ecological Indicators 116, no. : 106479.
With the decline in the most fisheries resources in the Yellow Sea, the yellow goosefish Lophius litulon has increased in commercial and ecological importance in recent years. We studied the length distribution, length-weight relationship, age composition, growth pattern, mortality, and exploitation rates of the yellow goosefish in the Yellow Sea. Total length (TL) of females and males ranged from 173 to 582 mm and 178 to 500 mm, respectively. The length-weight relationships were also estimated for females and males. Age classes from 2 to 4 years predominated in the samples. The von Bertalanffy growth function (VBGF), estimated based on non-linear least-squares methodology, showed significant differences between sexes. Females attained a greater estimated asymptotic total length (765 mm TL) compared to males (579 mm TL). The VBGF did not differ significantly between stocks of the northern Yellow Sea and the southern Yellow Sea. Estimated natural instantaneous mortality rate (M) ranged from 0.25/a to 0.33/a based on four age- and length-based methods. Total instantaneous mortality rate (Z) of total samples calculated by the age-based catch curve method was 0.591/a and the average fishing mortality (F) was 0.30/a. Estimated exploitation rate (E) was approximately 0.5, indicating that the population of L. litulon in the Yellow Sea may be sustainable. These results provide a reference for the present status of L. litulon and information for the management.
Yu Sun; Chi Zhang; Yongjun Tian; Yoshiro Watanabe. Age, growth, and mortality rate of the yellow goosefish Lophius litulon (Jordan, 1902) in the Yellow Sea. Journal of Oceanology and Limnology 2020, 39, 732 -740.
AMA StyleYu Sun, Chi Zhang, Yongjun Tian, Yoshiro Watanabe. Age, growth, and mortality rate of the yellow goosefish Lophius litulon (Jordan, 1902) in the Yellow Sea. Journal of Oceanology and Limnology. 2020; 39 (2):732-740.
Chicago/Turabian StyleYu Sun; Chi Zhang; Yongjun Tian; Yoshiro Watanabe. 2020. "Age, growth, and mortality rate of the yellow goosefish Lophius litulon (Jordan, 1902) in the Yellow Sea." Journal of Oceanology and Limnology 39, no. 2: 732-740.
The Japanese Spanish mackerel Scomberomorus niphonius (Cuvier, 1832) is widely distributed in the subtropical and temperate waters of the northwestern Pacific Ocean, supporting one of the most important commercial fisheries in China. However, ignoring the potential population structure changes induced by fishing pressure and climate change may undermine the population stability under the current management strategy. In this study, the population structure of the Japanese Spanish mackerel was investigated based on a morphometric truss network system. A total of 534 individuals were randomly collected from commercial gill nets spanning eight major spawning grounds in the Bohai, Yellow, and East China Seas during the peak spawning seasons respectively. A total of 17 measurements (including eye diameter) were conducted in each specimen and subjected to principal component analysis (PCA) and discriminant function analysis (DFA). The results of PCA indicated that the first two factors cumulatively caused 78.38% of the total morphometric variation and observable differences, primarily fin the caudal and trunk areas. The results of DFA revealed that the eight spawning groups can be divided into three stocks, i.e., southern, middle, and northern stocks, with 68.7% of total accuracy. In contrast to previous studies, the spawning groups of the Japanese Spanish mackerel demonstrated a tendency to disperse to northern regions. In conclusion, this study found that to maintain the stability of the population structure and the total production of Japanese Spanish mackerel S. niphonius (Cuvier, 1832), a newly revised management method should be developed and implemented.
Yiqian Jiang; Chi Zhang; Zhenjiang Ye; Binduo Xu; Yongjun Tian; Yoshiro Watanabe. Stock Structure Analysis of the Japanese Spanish Mackerel Scomberomorus niphonius (Cuvier, 1832) Along the China Coast Based on Truss Network. Journal of Ocean University of China 2020, 19, 446 -452.
AMA StyleYiqian Jiang, Chi Zhang, Zhenjiang Ye, Binduo Xu, Yongjun Tian, Yoshiro Watanabe. Stock Structure Analysis of the Japanese Spanish Mackerel Scomberomorus niphonius (Cuvier, 1832) Along the China Coast Based on Truss Network. Journal of Ocean University of China. 2020; 19 (2):446-452.
Chicago/Turabian StyleYiqian Jiang; Chi Zhang; Zhenjiang Ye; Binduo Xu; Yongjun Tian; Yoshiro Watanabe. 2020. "Stock Structure Analysis of the Japanese Spanish Mackerel Scomberomorus niphonius (Cuvier, 1832) Along the China Coast Based on Truss Network." Journal of Ocean University of China 19, no. 2: 446-452.
The assessment of extreme weather events on suitable sites for aquaculture could help in establishing sustainable coastal environmental resource management. Japanese scallop culture is an economically important marine farming activity in the coastal communities of Shandong, China and Funka Bay, Japan. In this study, we improved the suitable aquaculture site-selection model (SASSM) by using Geostationary Ocean Color Imager (GOCI) data instead of Moderate Resolution Imaging Spectroradiometer (MODIS) data, as a complementary source for higher temporal and spatial resolution data that are useful for monitoring fine-scale coastal and oceanic processes. We also applied the newly developed SASSM to the Japanese scallop production site along the Shandong coast. Finally, we analyzed the correlations between environmental factors (chlorophyll a concentration, sea surface temperature (SST), and total suspended sediment), meteorological factors (precipitation, temperature, and wind), and climatic events (winter East Asian monsoon (EAM) and El Niño/La Niña Southern Oscillation), and the impacts of climate events on suitable zones for scallop aquaculture. The new SASSM maps show that GOCI products have the potential for oceanographic investigations in Shandong, China and Funka Bay, Japan. Our results highlighted higher aquaculture site suitability for scallop in Funka Bay than in Shandong coast. During the winter with a strong EAM (2011), the suitable area for Japanese scallop aquaculture increased. Conversely, in the winter during a strong El Niño (2016), we found fewer areas that were highly suitable for scallop aquaculture in Funka Bay. SST was extremely low in Funka Bay during spring and summer 2017, which caused fewer highly suitable areas (scores of 7 and 8) for scallop aquaculture relative to other years. These findings suggest that extreme climatic events significantly impact the availability of suitable sites for marine farming and thus, should be considered in the development and design of coastal aquaculture sites.
Yang Liu; Yongjun Tian; Sei-Ichi Saitoh; Irene D. Alabia; Kan-Ichiro Mochizuki. Impact of Climate Extremes on Suitability Dynamics for Japanese Scallop Aquaculture in Shandong, China and Funka Bay, Japan. Sustainability 2020, 12, 833 .
AMA StyleYang Liu, Yongjun Tian, Sei-Ichi Saitoh, Irene D. Alabia, Kan-Ichiro Mochizuki. Impact of Climate Extremes on Suitability Dynamics for Japanese Scallop Aquaculture in Shandong, China and Funka Bay, Japan. Sustainability. 2020; 12 (3):833.
Chicago/Turabian StyleYang Liu; Yongjun Tian; Sei-Ichi Saitoh; Irene D. Alabia; Kan-Ichiro Mochizuki. 2020. "Impact of Climate Extremes on Suitability Dynamics for Japanese Scallop Aquaculture in Shandong, China and Funka Bay, Japan." Sustainability 12, no. 3: 833.
Largehead hairtail (Trichiurus japonicus) is an important fish species in China Sea, characterized by wide distribution, extensive migration, long spawning period and high economic value. The East China Sea is one of the typical over-exploited ecosystems in the world where most of the fish populations are overfished. In spite of high fishing pressure over an extended period, the catch of largehead hairtail showed an increasing trend in recent years. In this study, using otolith microstructure analysis for daily ageing, we explored spawning seasonality of largehead hairtail and daily growth of young-of-the-year (YoY) largehead hairtail in the East China Sea. Spawning seasonality of largehead hairtail was found to be nearly year round with two dominant seasons: autumn and spring. The gradient forest method was used to identify the relative importance of various environmental variables in relation to daily growth of YoY largehead hairtail; the first six most important environmental variables were subsequently analyzed using generalized additive models for their specific associations with daily growth of YoY largehead hairtail. Results show that sea surface temperature (SST), sea bottom temperature (SBT), temperature difference (TD) between surface and bottom water, and mixed layer depth (MLD) are the most important variables for daily growth of almost all month cohorts. In addition, the consistent interactive effects of water temperature (SST and SBT) and MLD suggest that daily growth of YoY largehead hairtail is influenced by the interactive effects of water temperature and nutrient supplies. This study highlights the importance of understanding the reproductive process and early growth of largehead hairtail in relation to environmental variables, which has important implications for the sustainable management and utilization of largehead hairtail in the over-exploited China Seas.
Peng Sun; Qi Chen; Caihong Fu; Wenbin Zhu; Jianchao Li; Chi Zhang; Haiqing Yu; Runlong Sun; Yi Xu; Yongjun Tian. Daily growth of young-of-the-year largehead hairtail (Trichiurus japonicus) in relation to environmental variables in the East China Sea. Journal of Marine Systems 2020, 201, 103243 .
AMA StylePeng Sun, Qi Chen, Caihong Fu, Wenbin Zhu, Jianchao Li, Chi Zhang, Haiqing Yu, Runlong Sun, Yi Xu, Yongjun Tian. Daily growth of young-of-the-year largehead hairtail (Trichiurus japonicus) in relation to environmental variables in the East China Sea. Journal of Marine Systems. 2020; 201 ():103243.
Chicago/Turabian StylePeng Sun; Qi Chen; Caihong Fu; Wenbin Zhu; Jianchao Li; Chi Zhang; Haiqing Yu; Runlong Sun; Yi Xu; Yongjun Tian. 2020. "Daily growth of young-of-the-year largehead hairtail (Trichiurus japonicus) in relation to environmental variables in the East China Sea." Journal of Marine Systems 201, no. : 103243.
Located at the margin of the Northwest Pacific Ocean, the Yellow Sea (YS) and East China Sea (ECS) marine ecosystems are mainly influenced by the Kuroshio and its branches. In addition to decadal changes in their marine environments, the YS and ECS have been impacted by intensive fishing at both the species- and community-levels, leading to over-exploitation of commercial species and changes in species composition and trophic structure. The dual effects of overfishing and climate change on the variability and processes of the YS and ECS ecosystem structure and functions are not well understood. In this study, we have compiled biological and physical time series, including 147 taxa catches, 7 local-scale environmental variables and 8 large-scale climate indices, to explore variations in ecosystem structure, and to elucidate the effects of climate change on the two regions during the period 1950-2014. Aside from fishing impacts, results show that decadal variations occurred in both the YS and ECS, with step-like changes around the mid-1960s, mid-1970s, late 1980s and late 1990s. These changes correspond well with contemporaneous climatic regime shifts in the Pacific. Climate-induced changing patterns are also evident in different fish communities, with diverse sensitivities in response to these patterns. Increasing water temperature exhibits greater effects on cold-water group than on temperate- and warm-water groups. Functional and thermal groups both show pronounced linkages with fishing effort and physical drivers, particularly with local-scale environmental variables, which highlights the importance of fishing and the validity of biological grouping in future investigation of environmental impacts on marine organisms. Our results provide evidences for climate-induced variations in over-exploited marine ecosystems and coupled “Atmosphere-Ocean-Ecosystem” influencing processes, which have important implications for ecosystem-based fisheries management in the YS and ECS.
Shuyang Ma; Yang Liu; Jianchao Li; Caihong Fu; Zhenjiang Ye; Peng Sun; Haiqing Yu; Jiahua Cheng; Yongjun Tian. Climate-induced long-term variations in ecosystem structure and atmosphere-ocean-ecosystem processes in the Yellow Sea and East China Sea. Progress in Oceanography 2019, 175, 183 -197.
AMA StyleShuyang Ma, Yang Liu, Jianchao Li, Caihong Fu, Zhenjiang Ye, Peng Sun, Haiqing Yu, Jiahua Cheng, Yongjun Tian. Climate-induced long-term variations in ecosystem structure and atmosphere-ocean-ecosystem processes in the Yellow Sea and East China Sea. Progress in Oceanography. 2019; 175 ():183-197.
Chicago/Turabian StyleShuyang Ma; Yang Liu; Jianchao Li; Caihong Fu; Zhenjiang Ye; Peng Sun; Haiqing Yu; Jiahua Cheng; Yongjun Tian. 2019. "Climate-induced long-term variations in ecosystem structure and atmosphere-ocean-ecosystem processes in the Yellow Sea and East China Sea." Progress in Oceanography 175, no. : 183-197.
Pacific saury (Cololabis saira) are widely distributed in northwestern Pacific, migrating from their spawning ground in subtropical Kuroshio waters south of Japan to feeding grounds in Oyashio waters northeast of Japan. The abundance of Pacific saury is expected to be affected not only by environmental conditions in the fishing grounds of the Oyashio region, but also by recruitment processes influenced by environmental conditions in the Kuroshio region. In this study, we focus on the effects of environmental variations in the spawning ground on Pacific saury abundance, approximated by catch and CPUE data. To examine interannual-decadal variability in the spawning ground, we developed a suite of spawning ground indices, including (1) average winter sea surface temperature (WSST), (2) the meridional position of 19 °C sea surface temperature (SST) isoline (MP19), and (3) SST-suitability-weighted size of spawning ground (WSSG), in the Kuroshio region. These spawning ground indices exhibited interannual-decadal variation patterns with regime shifts in 1962/63, 1976/77, 1987/88, 1997/98, and likely in the early 2010s, which corresponded well to data on catch and CPUE of Pacific saury. Large scale climatic indices such as Southern Oscillation Index (SOI) and Asian Monsoon Index (MOI) were negatively correlated with winter SST in most of the Kuroshio region, suggesting that large-scale climatic influences played important roles in the variability of SST within the Kuroshio region. Gradient forest analyses were used to quantify the importance of these spawning ground indices for explaining the variations of Pacific saury abundance and to identify shifts in catch and CPUE along the gradients of the spawning ground indices. MP19 with a 2-year lag (MP19_Lag2) was identified as the most important predictor of Pacific saury abundance in terms of CPUE, followed by WSST_Lag2, WSST, WSSG_Lag1, and WSSG. Spawning ground indices, particularly MP19_Lag2, were useful for rationalizing the dynamics of Pacific saury abundance, matching well the striking declines of catch both in the early 1960s and also in the most recent years.
Shigang Liu; Yang Liu; Caihong Fu; Luxin Yan; Yi Xu; Rong Wan; Jianchao Li; Yongjun Tian. Using novel spawning ground indices to analyze the effects of climate change on Pacific saury abundance. Journal of Marine Systems 2018, 191, 13 -23.
AMA StyleShigang Liu, Yang Liu, Caihong Fu, Luxin Yan, Yi Xu, Rong Wan, Jianchao Li, Yongjun Tian. Using novel spawning ground indices to analyze the effects of climate change on Pacific saury abundance. Journal of Marine Systems. 2018; 191 ():13-23.
Chicago/Turabian StyleShigang Liu; Yang Liu; Caihong Fu; Luxin Yan; Yi Xu; Rong Wan; Jianchao Li; Yongjun Tian. 2018. "Using novel spawning ground indices to analyze the effects of climate change on Pacific saury abundance." Journal of Marine Systems 191, no. : 13-23.