《渔业科学进展》虚拟专辑——渔业资源与环境
关键词：暂无
2024, 45(4):1-14.
DOI: 10.19663/j.issn2095-9869.20230411002
Abstract:
The Anqing section of the Yangtze (Changjiang) River in Anhui Province, China, is one of the most important migratory routes and distribution of the highly valued diadromous estuarine tapertail anchovy Coilia nasus. In the past, this section has suffered a severe loss of C. nasus resources caused by human activities, especially overfishing and water pollution. Since 2019, a fishing ban policy for the species in the Yangtze River has been introduced in China for resource restoration. Otoliths are calcium carbonate structures, and otolith microchemistry can provide detailed life history information that can be used to compare habitat use between different saline water bodies. To study the habitat history of C. nasus in the Anqing section of the Yangtze River after the implementation of the fishing ban, we examined the microchemical characteristics (Sr and Ca) of otoliths from the long (previously named C. ectenes) and short maxillary (previously named C. brachygnathus) types of anchovy using electron probe X-ray microanalysis (EPMA). Line-transect analysis of Sr/Ca ratios suggested that the short maxillary type of C. nasus could be divided into two groups. The otolith Sr/Ca ratios (calculated and expressed as Sr/Ca ×1,000) of one group were always < 3.0, indicating their freshwater residency. Those of the other group had phases of low (< 3.0, believed to be indicative of a freshwater habitat) and high values (> 3.0, believed to be indicative of a brackish or seawater habitat), indicating that anchovies not only have a freshwater habitat history with low salinity but also a brackish habitat history with high salinity. The latter group of anchovies were typically anadromous C. nasus, as the Sr/Ca ratio of the otoliths of C. nasus fluctuated significantly and coincided with variations between freshwater and estuarine brackish or seawater (i.e., anchovies experienced not only freshwater habitats but also brackish water habitats at different stages of their life history). The Sr content mapping of EPMA with different color patterns for freshwater (blue), brackish water (green-yellow) and seawater (red) habitats also confirmed the results obtained from the line-transect analysis. Our results demonstrated that the population composition of C. nasus in the Anqing section of the Yangtze river became complex, and there was coexistence of freshwater resident and anadromous C. nasus in the Anqing section of the Yangtze River in Anhui Province, China (i.e., freshwater resident and anadromous short maxillary and anadromous long maxillary type C. nasus). This phenomenon may suggest a restoration of C. nasus resource diversity after the implementation of the fishing ban in the Anqing section of the Yangtze River.
The Anqing section of the Yangtze (Changjiang) River in Anhui Province, China, is one of the most important migratory routes and distribution of the highly valued diadromous estuarine tapertail anchovy Coilia nasus. In the past, this section has suffered a severe loss of C. nasus resources caused by human activities, especially overfishing and water pollution. Since 2019, a fishing ban policy for the species in the Yangtze River has been introduced in China for resource restoration. Otoliths are calcium carbonate structures, and otolith microchemistry can provide detailed life history information that can be used to compare habitat use between different saline water bodies. To study the habitat history of C. nasus in the Anqing section of the Yangtze River after the implementation of the fishing ban, we examined the microchemical characteristics (Sr and Ca) of otoliths from the long (previously named C. ectenes) and short maxillary (previously named C. brachygnathus) types of anchovy using electron probe X-ray microanalysis (EPMA). Line-transect analysis of Sr/Ca ratios suggested that the short maxillary type of C. nasus could be divided into two groups. The otolith Sr/Ca ratios (calculated and expressed as Sr/Ca ×1,000) of one group were always < 3.0, indicating their freshwater residency. Those of the other group had phases of low (< 3.0, believed to be indicative of a freshwater habitat) and high values (> 3.0, believed to be indicative of a brackish or seawater habitat), indicating that anchovies not only have a freshwater habitat history with low salinity but also a brackish habitat history with high salinity. The latter group of anchovies were typically anadromous C. nasus, as the Sr/Ca ratio of the otoliths of C. nasus fluctuated significantly and coincided with variations between freshwater and estuarine brackish or seawater (i.e., anchovies experienced not only freshwater habitats but also brackish water habitats at different stages of their life history). The Sr content mapping of EPMA with different color patterns for freshwater (blue), brackish water (green-yellow) and seawater (red) habitats also confirmed the results obtained from the line-transect analysis. Our results demonstrated that the population composition of C. nasus in the Anqing section of the Yangtze river became complex, and there was coexistence of freshwater resident and anadromous C. nasus in the Anqing section of the Yangtze River in Anhui Province, China (i.e., freshwater resident and anadromous short maxillary and anadromous long maxillary type C. nasus). This phenomenon may suggest a restoration of C. nasus resource diversity after the implementation of the fishing ban in the Anqing section of the Yangtze River.
2024, 45(1):148-160.
DOI: 10.19663/j.issn2095-9869.20220726002
Abstract:
Eriocheir sinensis is an important fishery resource in the Yangtze River basin, which has brought about huge socio-economic benefits. The estuarine spawning grounds of E. sinensis, however, has experienced negative effects, such as habitat alteration and degradation of the water environment, in the mid- to late 1980s as a result of the construction of water conservation projects, land reclamation along the estuary, and pollution input. In addition, the overexploitation of E. sinensis resources has contributed to a sharp decline in its resources. To develop rational and scientific habitat management plans, the estuarine spawning habitats of E. sinensis have received attention in recent years. Currently, the distribution pattern and habitat characteristics of E. sinensis spawning grounds in the Yangtze River estuary have been explored from the perspective of resource distribution; however, habitat quality has not been further investigated. Studies on habitat quality can more effectively support the development of fishery habitat management strategies by serving as a tool to objectively assess the functional status of aquatic habitats. The habitat quality of the Yangtze River estuary has a substantial impact on the resources of E. sinensis as it is the only spawning ground for this species in the Yangtze River basin and is also the largest in China. Therefore, the behavior of E. sinensis during reproduction and spawning, which reflects the habitat quality of the spawning grounds, served as the foundation for this study. The evaluation of the habitat quality of E. sinensis spawning grounds was based on the parameters of reproductive performance and quantitative distribution. The habitat quality index (HQI) of E. sinensis spawning grounds was built by screening evaluation indices, weight analysis of evaluation indices, and construction of evaluation criteria. To provide the necessary scientific tools for examining E. sinensis spawning grounds in the Yangtze River estuary and to establish a solid scientific foundation for managing estuarine spawning grounds for this species. The spawning grounds of the Yangtze River estuary were monitored using egg-holding crabs of E. sinensis, and sampling was performed using gillnets positioned at certain locations. Key environmental parameters influencing the spawning activity of E. sinensis, such as water depth, turbidity, dissolved oxygen (DO) in bottom water, salinity (SAL), and temperature (T) were gathered during the sampling process. Through anatomical measurements of collected egg-holding crabs, physiological characteristics including carapace width, absolute fecundity, relative fecundity, condition factor, hepatopancreas index, and reproductive effort were gathered and collected. The characteristics of egg-holding crab population distribution and reproductive success were key factors considered when choosing the evaluation indices. The catch per unit effort of egg-holding crabs is a quantitative distribution characteristic, and the reproductive performance characteristics primarily rely on correlation analysis to determine the traits that can objectively respond to the reproductive performance of egg-holding crab, which are RF and HSI. Subsequently, a hierarchical evaluation system is created based on the characteristics of the evaluation indices. The response relationship between the environmental elements and each evaluation index serves as the foundation for the weight analysis of the evaluation indices. The environmental factors were analyzed separately with each evaluation index for redundancy analysis (RDA), and the results of the RDA were used to understand the degree of influence of each evaluation index on environmental characteristics. It is also used as the basis for the weight value of the evaluation indices, and the weight value of each evaluation index is determined by combining the hierarchical analysis method. Finally, a multi-index comprehensive scoring technique was used to determine the HQI of the E. sinensis spawning grounds, and guidelines for evaluating habitat quality were developed. The findings revealed a strong response relationship between egg-holding crab reproductive performance characteristic indicators and environmental factors (91.9%, F=9.0, P=0.042), which has significant application value when assessing the habitat quality of their spawning grounds. The evaluation revealed that the survey sites´ HQIs ranged from 0.33 to 0.84, and 47% of the survey sites assigned a "medium" or higher rating to the habitat quality level. Overall, the northern bank of Hengsha had a greater habitat quality than the deepwater canal. The HQI developed in this study has obvious advantages in quantitatively assessing the habitat quality of E. sinensis spawning grounds because it has a greater interpretation rate of environmental elements (94.9%, F=12.0, P=0.038) than quantitative distribution characteristics. The maximum percentage of HQI was explained by DO, SAL, and T when each environmental factor was used as an independent explanatory variable, accounting for 74.0% (F=22.7, P=0.004), 44.0% (F=6.3, P=0.044), and 33.0% (F=3.9, P=0.076), respectively. DO, SAL, and T were the key environmental factors influencing the habitat quality of E. sinensis spawning grounds. In this study, the Yangtze River estuary was chosen as the spawning ground for E. sinensis, and the quantitative distribution and reproductive performance characteristics of this species were employed as the foundation for evaluating habitat quality. The spawning grounds of the Yangtze River estuary for E. sinensis were further investigated in terms of habitat function using the HQI, which was built based on the characteristics of the evaluation indices. This study identified the major habitat factors that influence the habitat quality of these spawning grounds.
Eriocheir sinensis is an important fishery resource in the Yangtze River basin, which has brought about huge socio-economic benefits. The estuarine spawning grounds of E. sinensis, however, has experienced negative effects, such as habitat alteration and degradation of the water environment, in the mid- to late 1980s as a result of the construction of water conservation projects, land reclamation along the estuary, and pollution input. In addition, the overexploitation of E. sinensis resources has contributed to a sharp decline in its resources. To develop rational and scientific habitat management plans, the estuarine spawning habitats of E. sinensis have received attention in recent years. Currently, the distribution pattern and habitat characteristics of E. sinensis spawning grounds in the Yangtze River estuary have been explored from the perspective of resource distribution; however, habitat quality has not been further investigated. Studies on habitat quality can more effectively support the development of fishery habitat management strategies by serving as a tool to objectively assess the functional status of aquatic habitats. The habitat quality of the Yangtze River estuary has a substantial impact on the resources of E. sinensis as it is the only spawning ground for this species in the Yangtze River basin and is also the largest in China. Therefore, the behavior of E. sinensis during reproduction and spawning, which reflects the habitat quality of the spawning grounds, served as the foundation for this study. The evaluation of the habitat quality of E. sinensis spawning grounds was based on the parameters of reproductive performance and quantitative distribution. The habitat quality index (HQI) of E. sinensis spawning grounds was built by screening evaluation indices, weight analysis of evaluation indices, and construction of evaluation criteria. To provide the necessary scientific tools for examining E. sinensis spawning grounds in the Yangtze River estuary and to establish a solid scientific foundation for managing estuarine spawning grounds for this species. The spawning grounds of the Yangtze River estuary were monitored using egg-holding crabs of E. sinensis, and sampling was performed using gillnets positioned at certain locations. Key environmental parameters influencing the spawning activity of E. sinensis, such as water depth, turbidity, dissolved oxygen (DO) in bottom water, salinity (SAL), and temperature (T) were gathered during the sampling process. Through anatomical measurements of collected egg-holding crabs, physiological characteristics including carapace width, absolute fecundity, relative fecundity, condition factor, hepatopancreas index, and reproductive effort were gathered and collected. The characteristics of egg-holding crab population distribution and reproductive success were key factors considered when choosing the evaluation indices. The catch per unit effort of egg-holding crabs is a quantitative distribution characteristic, and the reproductive performance characteristics primarily rely on correlation analysis to determine the traits that can objectively respond to the reproductive performance of egg-holding crab, which are RF and HSI. Subsequently, a hierarchical evaluation system is created based on the characteristics of the evaluation indices. The response relationship between the environmental elements and each evaluation index serves as the foundation for the weight analysis of the evaluation indices. The environmental factors were analyzed separately with each evaluation index for redundancy analysis (RDA), and the results of the RDA were used to understand the degree of influence of each evaluation index on environmental characteristics. It is also used as the basis for the weight value of the evaluation indices, and the weight value of each evaluation index is determined by combining the hierarchical analysis method. Finally, a multi-index comprehensive scoring technique was used to determine the HQI of the E. sinensis spawning grounds, and guidelines for evaluating habitat quality were developed. The findings revealed a strong response relationship between egg-holding crab reproductive performance characteristic indicators and environmental factors (91.9%, F=9.0, P=0.042), which has significant application value when assessing the habitat quality of their spawning grounds. The evaluation revealed that the survey sites´ HQIs ranged from 0.33 to 0.84, and 47% of the survey sites assigned a "medium" or higher rating to the habitat quality level. Overall, the northern bank of Hengsha had a greater habitat quality than the deepwater canal. The HQI developed in this study has obvious advantages in quantitatively assessing the habitat quality of E. sinensis spawning grounds because it has a greater interpretation rate of environmental elements (94.9%, F=12.0, P=0.038) than quantitative distribution characteristics. The maximum percentage of HQI was explained by DO, SAL, and T when each environmental factor was used as an independent explanatory variable, accounting for 74.0% (F=22.7, P=0.004), 44.0% (F=6.3, P=0.044), and 33.0% (F=3.9, P=0.076), respectively. DO, SAL, and T were the key environmental factors influencing the habitat quality of E. sinensis spawning grounds. In this study, the Yangtze River estuary was chosen as the spawning ground for E. sinensis, and the quantitative distribution and reproductive performance characteristics of this species were employed as the foundation for evaluating habitat quality. The spawning grounds of the Yangtze River estuary for E. sinensis were further investigated in terms of habitat function using the HQI, which was built based on the characteristics of the evaluation indices. This study identified the major habitat factors that influence the habitat quality of these spawning grounds.
LI Xiangyan
,
TIAN Huiwu
,
PU Yan
,
TANG Xiliang
,
YAN Zhongluan
,
CHEN Daqing
,
LIU Shaoping
,
DUAN Xinbin
2022, 43(4):93-104.
DOI: 10.19663/j.issn2095-9869.20210319002
Abstract:
To understand the status of early-stage fish resources in the Yibin Section in the upper reaches of the Yangtze River and guide the protection of fish resources in this section, surveys were carried out from April to July in the years of 2017~2019. The results showed that there were 22 species of eggs and larvae in five families and three orders, and the largest proportion was in the Cyprinidae. Among these, 13 species produced drifting eggs, and six species were endemic to the upper reaches of the Yangtze River. The breeding time of different fish had obvious annual differences, but the peak of fish breeding occurred in June. From 2017 to 2019, the number of drifting eggs was estimated to be 12.10×106, 70.42×106, and 35.77×106 for each year, respectively. The number of larvae was estimated to be 30.95×106, 41.47×106, and 39.44×106, respectively. The number of eggs of endemic fish in the upper reaches of the Yangtze River was estimated at 15.91×106 over three years. According to the calculation, there were many spawning sites of fish drifting upstream of the Yibin Section, and the larger spawning sites were mainly located in the reaches of Zhouba, Peachwan, and Hualong Wharf. The spawning sites of Rhinogobio typus were distributed from Dongyuemiao to Xiangjiaba, with the largest cumulative spawning amount in three years, up to 40.93×106. The spawning grounds of R. typus tended to migrate downstream. The spawning grounds of Ctenopharyngodon idellus are mainly distributed in the Mamingxi Wharf and Peachwan areas. The results of the canonical correlation analysis showed that environmental factors such as water level, water temperature, and water discharge had different effects on the density of drifting fish eggs. Lepturichthys fimbriata and Parabotia fasciata lay eggs when the water temperature and water discharge are high. The reproductive conditions of C. idellus and Leptobotia microphthalma were similar to each other, and they were highly correlated with the water level, water discharge, and velocity. The spawning of R. typus and Coreius heterokon was significantly affected by changes in dissolved oxygen and transparency. Although affected by many factors, such as the development of cascade hydropower in the Jinsha River, the Yibin Section, as an important part of the mainstream national nature reserve of rare and endemic fish in the upper Yangtze River, is still a crucial distribution area for the spawning and breeding of many fish species, and the fish populations have slowly recovered in recent years. Therefore, we should strengthen the early resource research in this section, carry out habitat conservation and remediation, and implement a “10-year Fishing Ban” to promote resource recovery.
To understand the status of early-stage fish resources in the Yibin Section in the upper reaches of the Yangtze River and guide the protection of fish resources in this section, surveys were carried out from April to July in the years of 2017~2019. The results showed that there were 22 species of eggs and larvae in five families and three orders, and the largest proportion was in the Cyprinidae. Among these, 13 species produced drifting eggs, and six species were endemic to the upper reaches of the Yangtze River. The breeding time of different fish had obvious annual differences, but the peak of fish breeding occurred in June. From 2017 to 2019, the number of drifting eggs was estimated to be 12.10×106, 70.42×106, and 35.77×106 for each year, respectively. The number of larvae was estimated to be 30.95×106, 41.47×106, and 39.44×106, respectively. The number of eggs of endemic fish in the upper reaches of the Yangtze River was estimated at 15.91×106 over three years. According to the calculation, there were many spawning sites of fish drifting upstream of the Yibin Section, and the larger spawning sites were mainly located in the reaches of Zhouba, Peachwan, and Hualong Wharf. The spawning sites of Rhinogobio typus were distributed from Dongyuemiao to Xiangjiaba, with the largest cumulative spawning amount in three years, up to 40.93×106. The spawning grounds of R. typus tended to migrate downstream. The spawning grounds of Ctenopharyngodon idellus are mainly distributed in the Mamingxi Wharf and Peachwan areas. The results of the canonical correlation analysis showed that environmental factors such as water level, water temperature, and water discharge had different effects on the density of drifting fish eggs. Lepturichthys fimbriata and Parabotia fasciata lay eggs when the water temperature and water discharge are high. The reproductive conditions of C. idellus and Leptobotia microphthalma were similar to each other, and they were highly correlated with the water level, water discharge, and velocity. The spawning of R. typus and Coreius heterokon was significantly affected by changes in dissolved oxygen and transparency. Although affected by many factors, such as the development of cascade hydropower in the Jinsha River, the Yibin Section, as an important part of the mainstream national nature reserve of rare and endemic fish in the upper Yangtze River, is still a crucial distribution area for the spawning and breeding of many fish species, and the fish populations have slowly recovered in recent years. Therefore, we should strengthen the early resource research in this section, carry out habitat conservation and remediation, and implement a “10-year Fishing Ban” to promote resource recovery.
2022, 43(5):1-7.
DOI: 10.19663/j.issn2095-9869.20220415001
Abstract:
Based on the Intergovernmental Panel on Climate Change interpretation of carbon sink and carbon source, and the characteristics of carbon sequestration by aquatic plants, this review revises the definition of fisheries carbon sink and carbon sink fisheries proposed in 2010. We emphasize the basic expression of the function of fisheries carbon sink and the important role of aquatic plants in them. We further explain the process and mechanism of promoting aquatic organisms to "remove and store" greenhouse gases (such as carbon dioxide) through algae culture, filter-feeding shellfish and fish aquaculture, fishing and enhancement of fishery stock, and other means. We analyzed the process and mechanism of carbon dioxide use by non-fed shellfish aquaculture by filtering phytoplankton and particulate organic matter, such as organic debris. Further, the characteristics of carbon usage, removal, storage, and release, and their quantitative relationships with energy budget are discussed. The analyses confirmed that shellfish aquaculture enhances the carbon sink capacity of aquatic ecosystem, and is a carbon sink rather than a carbon source. Our results revealed that with the continuous development of mariculture production, the carbon sink of shellfish mariculture in the coastal ocean of China has substantially increased in the past 20 years. The total carbon sink increased from 3.94 million tons in 2001 to 6.59 million tons in 2020. This included an average of 6.48 million tons/year in the past three years (2018—2020), equivalent to 870 000 hectares of compulsory afforestation per year. The net carbon sink increased from 2.55 million tons to 4.3 million tons in 2020, with an average of 4.22 million tons/year in the last three years (2018—2020), equivalent to 560 000 hectares of compulsory afforestation per year. Finally, relevant suggestions for sustainable and further development of carbon sink fishery are proposed.
Based on the Intergovernmental Panel on Climate Change interpretation of carbon sink and carbon source, and the characteristics of carbon sequestration by aquatic plants, this review revises the definition of fisheries carbon sink and carbon sink fisheries proposed in 2010. We emphasize the basic expression of the function of fisheries carbon sink and the important role of aquatic plants in them. We further explain the process and mechanism of promoting aquatic organisms to "remove and store" greenhouse gases (such as carbon dioxide) through algae culture, filter-feeding shellfish and fish aquaculture, fishing and enhancement of fishery stock, and other means. We analyzed the process and mechanism of carbon dioxide use by non-fed shellfish aquaculture by filtering phytoplankton and particulate organic matter, such as organic debris. Further, the characteristics of carbon usage, removal, storage, and release, and their quantitative relationships with energy budget are discussed. The analyses confirmed that shellfish aquaculture enhances the carbon sink capacity of aquatic ecosystem, and is a carbon sink rather than a carbon source. Our results revealed that with the continuous development of mariculture production, the carbon sink of shellfish mariculture in the coastal ocean of China has substantially increased in the past 20 years. The total carbon sink increased from 3.94 million tons in 2001 to 6.59 million tons in 2020. This included an average of 6.48 million tons/year in the past three years (2018—2020), equivalent to 870 000 hectares of compulsory afforestation per year. The net carbon sink increased from 2.55 million tons to 4.3 million tons in 2020, with an average of 4.22 million tons/year in the last three years (2018—2020), equivalent to 560 000 hectares of compulsory afforestation per year. Finally, relevant suggestions for sustainable and further development of carbon sink fishery are proposed.
2021, 42(2):10-17.
DOI: 10.19663/j.issn2095-9869.20191025001
Abstract:
This study analyzed the carbon and nitrogen stable isotopes from 36 species of marine fishes in the Yellow Sea and northern East China Sea in 2011~2014. The feeding characters were determined by calculating the benthos proportion (Bp) with the δ13C data, and the trophic levels (TLs) were calculated using the δ15N data. The results showed that the trophic levels of the fishes ranged from 2.75 to 4.34 (mean 3.47). Four of the 36 species were completely plankton-feeding, and eight of them were benthos-feeding. The number of mixed feeding and complete benthos-feeding species was 12. Most of the fish species (91.67%) belonged to the middle (TL=3.5~4) and low (TL<3.5) trophic levels. However, the number of high trophic level (TL>4) species was only 3, and all were mixed feeding. In contrast to the TL research results of 1986, 1992, and 2004, the authors of this paper found that the trophic levels of some species had changed slightly in recent years. For example, the TL of Scomberomorus niphonius had decreased to varying degrees, while that of Setipinna taty had increased to a certain extent. The feeding character results were compared to those of 2004, 2009, and 2011. It showed that the feeding character of some fishes, such as Argyrosomus argentatus, had changed significantly. That of others, such as Larimichthys polyactis, had not changed significantly.
This study analyzed the carbon and nitrogen stable isotopes from 36 species of marine fishes in the Yellow Sea and northern East China Sea in 2011~2014. The feeding characters were determined by calculating the benthos proportion (Bp) with the δ13C data, and the trophic levels (TLs) were calculated using the δ15N data. The results showed that the trophic levels of the fishes ranged from 2.75 to 4.34 (mean 3.47). Four of the 36 species were completely plankton-feeding, and eight of them were benthos-feeding. The number of mixed feeding and complete benthos-feeding species was 12. Most of the fish species (91.67%) belonged to the middle (TL=3.5~4) and low (TL<3.5) trophic levels. However, the number of high trophic level (TL>4) species was only 3, and all were mixed feeding. In contrast to the TL research results of 1986, 1992, and 2004, the authors of this paper found that the trophic levels of some species had changed slightly in recent years. For example, the TL of Scomberomorus niphonius had decreased to varying degrees, while that of Setipinna taty had increased to a certain extent. The feeding character results were compared to those of 2004, 2009, and 2011. It showed that the feeding character of some fishes, such as Argyrosomus argentatus, had changed significantly. That of others, such as Larimichthys polyactis, had not changed significantly.
2019, 40(5):42-51.
DOI: 10.19663/j.issn2095-9869.20180514001
Abstract:
Phytoplankton are the major primary producers in the ocean and play a crucial role in the marine food chain. Understanding the dynamics of the marine phytoplankton community can provide insights into the succession process and current status of marine fishery resources. Based on the net-phytoplankton samples collected from the Bohai Sea in the summer (June and August) of 2015, we studied the phytoplankton community composition, diversity, abundance, and dominant taxa in the Bohai Sea. Compared with historical data, the phytoplankton community structure in the Bohai Sea was changed markedly. The chlorophyll-a concentration had changed slightly during recent years, but was much higher than that in the 1980s and 1990s, and the regions with lower values (<1.0 μg/L) were much smaller than those 20 years ago. In terms of the dominant taxa, the dominance of the genera Chaetoceros and Coscinodiscus was found to be slightly decreased, whereas the species Skeletonema costatum, which had been an important dominant species in the Bohai Sea, was not observed in the two months of summer in 2015. In contrast, Paralia sulcata and Pyrrophyta (Noctiluca scientillans in June and Ceratium tripos in August) were still dominant in the Bohai Sea, and the abundance and dominance of Achnanthes brevipes and Pseudo-nitzschia pungens was higher than those in the years before 2015. The diversity indices (Shannon diversity and species richness and evenness) of phytoplankton were at a moderate level. Such a trend was mainly caused by the significant change of the nutrient structure in the Bohai Sea. This may change the structure of the marine food chain and influence the growth and reproduction of commercial fishes and shrimps (e.g., Konosirus punctatus, Liza haematocheila, and Acetes chinensis) that feed on phytoplankton. Consequently, this will have potential impacts on fishery production and the structure and function of the ecosystem in the Bohai Sea.
Phytoplankton are the major primary producers in the ocean and play a crucial role in the marine food chain. Understanding the dynamics of the marine phytoplankton community can provide insights into the succession process and current status of marine fishery resources. Based on the net-phytoplankton samples collected from the Bohai Sea in the summer (June and August) of 2015, we studied the phytoplankton community composition, diversity, abundance, and dominant taxa in the Bohai Sea. Compared with historical data, the phytoplankton community structure in the Bohai Sea was changed markedly. The chlorophyll-a concentration had changed slightly during recent years, but was much higher than that in the 1980s and 1990s, and the regions with lower values (<1.0 μg/L) were much smaller than those 20 years ago. In terms of the dominant taxa, the dominance of the genera Chaetoceros and Coscinodiscus was found to be slightly decreased, whereas the species Skeletonema costatum, which had been an important dominant species in the Bohai Sea, was not observed in the two months of summer in 2015. In contrast, Paralia sulcata and Pyrrophyta (Noctiluca scientillans in June and Ceratium tripos in August) were still dominant in the Bohai Sea, and the abundance and dominance of Achnanthes brevipes and Pseudo-nitzschia pungens was higher than those in the years before 2015. The diversity indices (Shannon diversity and species richness and evenness) of phytoplankton were at a moderate level. Such a trend was mainly caused by the significant change of the nutrient structure in the Bohai Sea. This may change the structure of the marine food chain and influence the growth and reproduction of commercial fishes and shrimps (e.g., Konosirus punctatus, Liza haematocheila, and Acetes chinensis) that feed on phytoplankton. Consequently, this will have potential impacts on fishery production and the structure and function of the ecosystem in the Bohai Sea.
2018, 39(4):9-18.
Abstract:
Based on phytoplankton net samples from the Bohai Sea from 1959 to 2015, the long-term changes in species composition, cell abundance, community structure, and species diversity were analyzed. A total of 77 genera and 170 taxa were recorded, most of which were temperate-coastal ecotype species. The composition pattern of the dominant taxa changed dramatically over the fifty-plus years. Centric diatoms such as Chaetoceros spp. and Coscinodiscus spp. dominated in the communities of last century, while Paralia sulcata, Thalassionema spp., and dinoflagellates such as Noctiluca scintillans and Tripos spp. gradually became predominant in this century. The cruise-averaged cell abundances ranged from 8.33 × 104 cells/m3 to 472 × 104 cells/m3, with diatoms accounting for 65.3%~99.8%. The abundances and species diversities declined to their lowest levels last century, whilst they had 1.5 times and 15.0% respective recoveries in this century. The persistent increase in seawater N∶P ratios in the Bohai Sea has led to a phytoplankton transition from diatom-dominated communities to communities co-dominated by diatoms and dinoflagellates, with an increase of 2.82 times in the ratio of diatoms to dinoflagellates in this century from that in the last century. The decadal changes in the phytoplankton community structure and its herbal diet basis in the Bohai Sea affect the recruitment process during the early life stages of the key resource species. This study provides a baseline database and references for discussion on the mechanisms of adaptive responses of fishery populations to the long-term environmental changes in the Bohai Sea.
Based on phytoplankton net samples from the Bohai Sea from 1959 to 2015, the long-term changes in species composition, cell abundance, community structure, and species diversity were analyzed. A total of 77 genera and 170 taxa were recorded, most of which were temperate-coastal ecotype species. The composition pattern of the dominant taxa changed dramatically over the fifty-plus years. Centric diatoms such as Chaetoceros spp. and Coscinodiscus spp. dominated in the communities of last century, while Paralia sulcata, Thalassionema spp., and dinoflagellates such as Noctiluca scintillans and Tripos spp. gradually became predominant in this century. The cruise-averaged cell abundances ranged from 8.33 × 104 cells/m3 to 472 × 104 cells/m3, with diatoms accounting for 65.3%~99.8%. The abundances and species diversities declined to their lowest levels last century, whilst they had 1.5 times and 15.0% respective recoveries in this century. The persistent increase in seawater N∶P ratios in the Bohai Sea has led to a phytoplankton transition from diatom-dominated communities to communities co-dominated by diatoms and dinoflagellates, with an increase of 2.82 times in the ratio of diatoms to dinoflagellates in this century from that in the last century. The decadal changes in the phytoplankton community structure and its herbal diet basis in the Bohai Sea affect the recruitment process during the early life stages of the key resource species. This study provides a baseline database and references for discussion on the mechanisms of adaptive responses of fishery populations to the long-term environmental changes in the Bohai Sea.
2018, 39(3):23-29.
Abstract:
An accurate grasp of species distribution is a requirement for biodiversity studies, and understanding species’ biomass is crucial to assessing ecosystem productivity and material cycles. Traditional bioassays and biomass assessments are based on data from trawl surveys. However, trawl surveys often do not provide a true reflection of species distribution and resource status because of differences in the living habits and resource status of different species. To accurately grasp species distribution and resource status, it is imperative to identify cost-effective aquatic organism survey methods to provide technical support for the research and protection of aquatic ecosystem biological diversity. In recent years, the rapid development of molecular biology research has transformed species identification methods from traditional morphological classifications to molecular biology-based techniques, especially the development and application of environmental DNA technology. Environmental DNA is a ubiquitous free radical released from the skin, mucus, saliva, sperm, secretions, eggs, feces, urine, blood, roots, leaves, fruits, pollen, and decaying bodies of DNA molecules. Environmental DNA technology refers to the method of qualitatively or quantitatively analyzing DNA fragments directly from environmental samples (such as soils, sediments, and water bodies) using sequencing techniques. Environmental DNA technology has become a novel method of aquatic organism survey, which is mainly used in processes such as the prevention and control of biological invasion, protection of endangered species, and evaluation of biodiversity and biomass. Here, we review the development of environmental DNA technology, the operational flow, and its application in aquatic ecosystems, as well as the advantages and existing problems. In addition, we project the prospect of environmental DNA in the field of ecology. We hope that this review will provide novel ideas and methods for the research and protection of the biological diversity of aquatic ecosystems to ensure that aquatic resources can be fully utilized.
An accurate grasp of species distribution is a requirement for biodiversity studies, and understanding species’ biomass is crucial to assessing ecosystem productivity and material cycles. Traditional bioassays and biomass assessments are based on data from trawl surveys. However, trawl surveys often do not provide a true reflection of species distribution and resource status because of differences in the living habits and resource status of different species. To accurately grasp species distribution and resource status, it is imperative to identify cost-effective aquatic organism survey methods to provide technical support for the research and protection of aquatic ecosystem biological diversity. In recent years, the rapid development of molecular biology research has transformed species identification methods from traditional morphological classifications to molecular biology-based techniques, especially the development and application of environmental DNA technology. Environmental DNA is a ubiquitous free radical released from the skin, mucus, saliva, sperm, secretions, eggs, feces, urine, blood, roots, leaves, fruits, pollen, and decaying bodies of DNA molecules. Environmental DNA technology refers to the method of qualitatively or quantitatively analyzing DNA fragments directly from environmental samples (such as soils, sediments, and water bodies) using sequencing techniques. Environmental DNA technology has become a novel method of aquatic organism survey, which is mainly used in processes such as the prevention and control of biological invasion, protection of endangered species, and evaluation of biodiversity and biomass. Here, we review the development of environmental DNA technology, the operational flow, and its application in aquatic ecosystems, as well as the advantages and existing problems. In addition, we project the prospect of environmental DNA in the field of ecology. We hope that this review will provide novel ideas and methods for the research and protection of the biological diversity of aquatic ecosystems to ensure that aquatic resources can be fully utilized.
2018, 39(6):11-23.
Abstract:
Liusha Bay is one of the main aquaculture areas of marine mollusks in Guangdong Province, characterized by the main producing areas of South Pearl. To assess the environmental effects of aquaculture activities, the phytoplankton composition, abundance, community structure, diversity, and water physicochemical factors were investigated in each season from August 2015 to May 2016. In total, 171 phytoplankton species were detected, with 122 species of diatom belonging to 43 genera, followed by dinoflagellates represented by 44 taxa (10 genera), blue-green algae by two taxa (two genera), chrysophyceae by two taxa (two genera), and euglena by one taxa (one genus). The range of phytoplankton density was 0.05×104~79.04×104 cells/L, which ranked as: summer > spring > autumn > winter. In general, the phytoplankton density in the outer bay was similar to that in the inner bay. The abundance of phytoplankton in summer was distinctly higher than that in the other three seasons. The most common dominant species were Chaetoceros crinitus, Trichodesmium erythraeum, and Coscinodiscus debilis in spring, Skeletonema costatum in summer, Chaetoceros pseudocurvisetus, Bacillaria paradoxa, and Chaetoceros lorenzianus in autumn, and Coscinodisus wailesii, Rhizosolenia delicatula, and Fragilaria islandica in winter. B. paradoxa was the dominant species in spring, autumn, and winter. T. erythraeum was the dominant species in all seasons except for autumn. Redundancy analysis suggested that the main variables affecting the dominant species were water temperature and nitrate (NO3-N) in spring, transparency in summer, and nitrite (NO2-N) in autumn and winter. The phytoplankton diversity and abundance of different cultured zones presented seasonal differences. Compared to 2012, the total coverage of the aquaculture zone in 2015 increased by approximately 50% in the outer bay. Furthermore, coverage of the pearl oyster farming zone decreased by about 90% in the inner bay. Both the distribution of the aquaculture zone and the scale of the mariculture species were significantly changed, and the characteristics of the phytoplankton community responded to these changes. In summer, cage fish farming could efficiently increase nutrient content in seawater and decrease phytoplankton diversity. Furthermore, phytoplankton abundance was decreased by large-scale scallop culture.
Liusha Bay is one of the main aquaculture areas of marine mollusks in Guangdong Province, characterized by the main producing areas of South Pearl. To assess the environmental effects of aquaculture activities, the phytoplankton composition, abundance, community structure, diversity, and water physicochemical factors were investigated in each season from August 2015 to May 2016. In total, 171 phytoplankton species were detected, with 122 species of diatom belonging to 43 genera, followed by dinoflagellates represented by 44 taxa (10 genera), blue-green algae by two taxa (two genera), chrysophyceae by two taxa (two genera), and euglena by one taxa (one genus). The range of phytoplankton density was 0.05×104~79.04×104 cells/L, which ranked as: summer > spring > autumn > winter. In general, the phytoplankton density in the outer bay was similar to that in the inner bay. The abundance of phytoplankton in summer was distinctly higher than that in the other three seasons. The most common dominant species were Chaetoceros crinitus, Trichodesmium erythraeum, and Coscinodiscus debilis in spring, Skeletonema costatum in summer, Chaetoceros pseudocurvisetus, Bacillaria paradoxa, and Chaetoceros lorenzianus in autumn, and Coscinodisus wailesii, Rhizosolenia delicatula, and Fragilaria islandica in winter. B. paradoxa was the dominant species in spring, autumn, and winter. T. erythraeum was the dominant species in all seasons except for autumn. Redundancy analysis suggested that the main variables affecting the dominant species were water temperature and nitrate (NO3-N) in spring, transparency in summer, and nitrite (NO2-N) in autumn and winter. The phytoplankton diversity and abundance of different cultured zones presented seasonal differences. Compared to 2012, the total coverage of the aquaculture zone in 2015 increased by approximately 50% in the outer bay. Furthermore, coverage of the pearl oyster farming zone decreased by about 90% in the inner bay. Both the distribution of the aquaculture zone and the scale of the mariculture species were significantly changed, and the characteristics of the phytoplankton community responded to these changes. In summer, cage fish farming could efficiently increase nutrient content in seawater and decrease phytoplankton diversity. Furthermore, phytoplankton abundance was decreased by large-scale scallop culture.
ZHANG Xue
,
XU Xiaofu
,
DAI Yuanyuan
,
WANG Hong
,
FANG Enjun
,
HOU Chunqiang
,
GAO Yan
,
GUO Biao
,
CHEN Wei
2018, 39(6):1-10.
Abstract:
Three cruises were conducted in May, July, and November 2016 in artificial reef areas constructed in 2010, 2012, and 2014, respectively, and the non-artificial reef area (control area) offshore of Tianjin with three sampling stations for each, totaling 12 sites. The results identified 58 taxa of phytoplankton belonging to 2 phyla and 28 genera. Among these species, Bacillariophyta includes 19 genera and 44 species, and Pyrrophyta includes 9 genera and 14 species. Diatom species are dominant, accounting for 75.9% of all species, followed by dinoflagellates, accounting for 24.1%. Dominant phytoplankton species are Coscinodiscus and Chaetoceros of Bacillariophyta, mainly Coscinodiscus wailesii, C. asteromphalus, C. granii, C. oculus-iridis, C. spp., Chaetoceros castracanei, Ch. lorenzianus, Ch. curvisetus, Pseudo-nitzschiapungens, Guianardia delicatula, Rhizosolenia setigera, Proboscia alata f. indica, and Noctilluca scintillans. Phytoplankton cell abundance showed obvious seasonal changes, with the average cell abundance in November, July, and May at 94.79×104 cell/m³, 39.53×104 cell/m³, and 21.5×104 cell/m³, respectively. Phytoplankton diversity index also had obvious seasonal variation. In November, the Shannon-Wiener diversity index, Margalef index, and Pielou index were higher than in May and July. Comparing the artificial reef areas with the control area, the phytoplankton cell abundance of the control in May was significantly higher than the artificial reef areas. In July and November, phytoplankton cell abundance at the artificial reef constructed in 2014 was significantly higher than other artificial reef areas and the control area. The diversity index in both the control and the artificial reef area constructed in 2012 was lower than the 2010 and 2014 reefs, and lowest in the non-artificial reef area. Clearly, the construction of an artificial reef had a significant effect in improving phytoplankton community diversity, but this diversity is not always increasing consistently but fluctuating.
Three cruises were conducted in May, July, and November 2016 in artificial reef areas constructed in 2010, 2012, and 2014, respectively, and the non-artificial reef area (control area) offshore of Tianjin with three sampling stations for each, totaling 12 sites. The results identified 58 taxa of phytoplankton belonging to 2 phyla and 28 genera. Among these species, Bacillariophyta includes 19 genera and 44 species, and Pyrrophyta includes 9 genera and 14 species. Diatom species are dominant, accounting for 75.9% of all species, followed by dinoflagellates, accounting for 24.1%. Dominant phytoplankton species are Coscinodiscus and Chaetoceros of Bacillariophyta, mainly Coscinodiscus wailesii, C. asteromphalus, C. granii, C. oculus-iridis, C. spp., Chaetoceros castracanei, Ch. lorenzianus, Ch. curvisetus, Pseudo-nitzschiapungens, Guianardia delicatula, Rhizosolenia setigera, Proboscia alata f. indica, and Noctilluca scintillans. Phytoplankton cell abundance showed obvious seasonal changes, with the average cell abundance in November, July, and May at 94.79×104 cell/m³, 39.53×104 cell/m³, and 21.5×104 cell/m³, respectively. Phytoplankton diversity index also had obvious seasonal variation. In November, the Shannon-Wiener diversity index, Margalef index, and Pielou index were higher than in May and July. Comparing the artificial reef areas with the control area, the phytoplankton cell abundance of the control in May was significantly higher than the artificial reef areas. In July and November, phytoplankton cell abundance at the artificial reef constructed in 2014 was significantly higher than other artificial reef areas and the control area. The diversity index in both the control and the artificial reef area constructed in 2012 was lower than the 2010 and 2014 reefs, and lowest in the non-artificial reef area. Clearly, the construction of an artificial reef had a significant effect in improving phytoplankton community diversity, but this diversity is not always increasing consistently but fluctuating.
2018, 39(3):11-22.
Abstract:
Studies of the food web are an important inlet to carry out integrative research on sustainable marine ecosystems. These investigations further highlight the main food chain in the study of end-to-end food webs, and the research is conducted at each trophic level (TL). Under multiple pressures of human activities and climatic change, coastal sea ecosystems have undergone significant changes. Therefore, it is very important to clarify the food contact and its present variation in the Bohai Sea ecosystem. In this study, we analyzed 27 different fish species with 10156 stomachs, collected from bottom trawl surveys during 2010~2011 in the Bohai Sea. The percentage frequencies of occurrence, number, and weight of different prey categories were calculated to describe the diet composition. The Shannon–Wiener diversity index was used to evaluate the dietary breadth of each fish. The TL of each fish was calculated, and then the fish were classified as low, medium, and high TL (≤3.8, 3.9~4.4, and ≥4.5, respectively). The results showed that the 27 fish species, including 12 low TL species (Clupanodon punctatus, Sardinella zunasi, Enedrias fangi, Thrissa kammalensis, Callionymus beniteguri, Cynoglossus joyneri, Cynoglossus lighti, Setipinna taty, Enchelyopus elongates, Chaeturichthys stigmatias, Trichiurus muticus, and Chaeturichthys hexanema), 12 medium TL species (Scomberomorus niphonius, Pseudosciaena polyactis, Hexagrammos otakii, Johnius belangerii, Sebastiscus marmoratus, Sebastodes fuscescens, Liparis tanakae, Platycephalus indicus, Hemitripterus villosus, Argyrosomus argentatus, Chelidonichthys kumu, and Lateolabrax japonicus) and three high TL species (Saurida elongate, Lophius litulon, and Sphyraena pinguis), were classified into omnivores, zooplanktivores, benthivores, mixed animal predators, and piscivores. Compared to that in the 1990s, the TL of each fish has not changed much. Three kinds of high TL fish belonged to the piscivores fish category, and their dietary breadth was very low, and so they were stenophagous fish. Finespot goby and small yellow croaker had the highest dietary breadth and were the most important prey species in the food web of the Bohai Sea ecosystem; therefore, their euryphage was beneficial to the material and energy flow of each trophic hierarchy in the food web. Presently, the food chain “zooplankton–anchovy–large piscivores fish” was basically destroyed, and so, the main food chains changed to “plants, organic detritus–Alpheidae– fishes” and “benthic animals–goby fish, small yellow croaker–large commercial fishes” in the food web of the Bohai Sea. The weakening of the pelagic food chain is not conducive to the carbon sink of the marine ecosystem and the material and energy flow of the food web. Therefore, studies of the end-to-end food web and the main food chain of the Bohai Sea should change accordingly.
Studies of the food web are an important inlet to carry out integrative research on sustainable marine ecosystems. These investigations further highlight the main food chain in the study of end-to-end food webs, and the research is conducted at each trophic level (TL). Under multiple pressures of human activities and climatic change, coastal sea ecosystems have undergone significant changes. Therefore, it is very important to clarify the food contact and its present variation in the Bohai Sea ecosystem. In this study, we analyzed 27 different fish species with 10156 stomachs, collected from bottom trawl surveys during 2010~2011 in the Bohai Sea. The percentage frequencies of occurrence, number, and weight of different prey categories were calculated to describe the diet composition. The Shannon–Wiener diversity index was used to evaluate the dietary breadth of each fish. The TL of each fish was calculated, and then the fish were classified as low, medium, and high TL (≤3.8, 3.9~4.4, and ≥4.5, respectively). The results showed that the 27 fish species, including 12 low TL species (Clupanodon punctatus, Sardinella zunasi, Enedrias fangi, Thrissa kammalensis, Callionymus beniteguri, Cynoglossus joyneri, Cynoglossus lighti, Setipinna taty, Enchelyopus elongates, Chaeturichthys stigmatias, Trichiurus muticus, and Chaeturichthys hexanema), 12 medium TL species (Scomberomorus niphonius, Pseudosciaena polyactis, Hexagrammos otakii, Johnius belangerii, Sebastiscus marmoratus, Sebastodes fuscescens, Liparis tanakae, Platycephalus indicus, Hemitripterus villosus, Argyrosomus argentatus, Chelidonichthys kumu, and Lateolabrax japonicus) and three high TL species (Saurida elongate, Lophius litulon, and Sphyraena pinguis), were classified into omnivores, zooplanktivores, benthivores, mixed animal predators, and piscivores. Compared to that in the 1990s, the TL of each fish has not changed much. Three kinds of high TL fish belonged to the piscivores fish category, and their dietary breadth was very low, and so they were stenophagous fish. Finespot goby and small yellow croaker had the highest dietary breadth and were the most important prey species in the food web of the Bohai Sea ecosystem; therefore, their euryphage was beneficial to the material and energy flow of each trophic hierarchy in the food web. Presently, the food chain “zooplankton–anchovy–large piscivores fish” was basically destroyed, and so, the main food chains changed to “plants, organic detritus–Alpheidae– fishes” and “benthic animals–goby fish, small yellow croaker–large commercial fishes” in the food web of the Bohai Sea. The weakening of the pelagic food chain is not conducive to the carbon sink of the marine ecosystem and the material and energy flow of the food web. Therefore, studies of the end-to-end food web and the main food chain of the Bohai Sea should change accordingly.
2017, 38(3):12-21.
DOI: 10.11758/yykxjz.20160210001
Abstract:
The big-eye tuna (Thunnus obesus) is the most commercially important tuna species in eastern Pacific Ocean. The fishery of this species has been managed by Inter-American Tropical Tuna Commission (IATTC). IATTC evaluates the stock of big-eye tuna annually using Stock Synthesis 3 (SS3). SS3 is one of the most commonly used models that assess age-structured fishery stock based on biological parameters and fishery data such as the annual catch, the age-composition, the length composition of catch and abundance indices. A recent assessment of the big-eye tuna stock in eastern Pacific Ocean indicated a small recovery of the spawning stock biomass (SSB) and the fishing mortality (F) with respect to biological reference points (BRPs). The integrated model effectively combines multiple data with various sources into single analysis, and propagates the uncertainties associated with model parameters and structures into model outputs such as the biomass time series and BRP. However, it is time-consuming to use full SS3 model to analyze the big-eye tuna stock as it has as many as 23 fisheries. Therefore, model simplification has become necessary to improve the analysis efficiency. In this study, we tried to simplify the SS3 modeling process by using 2 fisheries (purse seine and longline fisheries) instead of 23. Representative abundance index and size composition from the purse seine fisheries and longline fisheries of the full model were used in the simplified one. The outputs of the simplified model were compared to that of the full model to evaluate the performance of the former. The results showed that the simplified model effectively captured the historical trends of stock time series (e.g., recruitments, SSB and F) and estimated FMSY with little interference from the steepness and natural mortality parameters. The reduced interference from steepness allowed the simplified model to correctly analyze the stock status based on the Kobe plot. However, the simplified model increased errors in the estimation of other BRPs. This study implied that selecting BRPs and defining stock status of big-eye tuna could affect the evaluation of the performance of the simplified model. Further studies are needed to achieve a balance between high performance and reduced complexity of the model.
The big-eye tuna (Thunnus obesus) is the most commercially important tuna species in eastern Pacific Ocean. The fishery of this species has been managed by Inter-American Tropical Tuna Commission (IATTC). IATTC evaluates the stock of big-eye tuna annually using Stock Synthesis 3 (SS3). SS3 is one of the most commonly used models that assess age-structured fishery stock based on biological parameters and fishery data such as the annual catch, the age-composition, the length composition of catch and abundance indices. A recent assessment of the big-eye tuna stock in eastern Pacific Ocean indicated a small recovery of the spawning stock biomass (SSB) and the fishing mortality (F) with respect to biological reference points (BRPs). The integrated model effectively combines multiple data with various sources into single analysis, and propagates the uncertainties associated with model parameters and structures into model outputs such as the biomass time series and BRP. However, it is time-consuming to use full SS3 model to analyze the big-eye tuna stock as it has as many as 23 fisheries. Therefore, model simplification has become necessary to improve the analysis efficiency. In this study, we tried to simplify the SS3 modeling process by using 2 fisheries (purse seine and longline fisheries) instead of 23. Representative abundance index and size composition from the purse seine fisheries and longline fisheries of the full model were used in the simplified one. The outputs of the simplified model were compared to that of the full model to evaluate the performance of the former. The results showed that the simplified model effectively captured the historical trends of stock time series (e.g., recruitments, SSB and F) and estimated FMSY with little interference from the steepness and natural mortality parameters. The reduced interference from steepness allowed the simplified model to correctly analyze the stock status based on the Kobe plot. However, the simplified model increased errors in the estimation of other BRPs. This study implied that selecting BRPs and defining stock status of big-eye tuna could affect the evaluation of the performance of the simplified model. Further studies are needed to achieve a balance between high performance and reduced complexity of the model.
SONG Yonggang
,
WU Jinhao
,
SHAO Zewei
,
YU Caifen
,
ZHANG Yufeng
,
DU Jing
,
JIANG Bing
,
SONG Lun
,
WANG Nianbin
2016, 37(3):14-19.
DOI: 10.11758/yykxjz.20150820001
Abstract:
Human activities have aggravated the offshore ecologic environment in the Liaodong Bay and endangered aquatic bioresources in these areas. The Liaodong Bay used to be an important fishing ground and the habitat of a variety of fish species such as Larimichthys polyactis, Trichiurus lepturus, and Fenneropenaeus chinensis. However, in recent years the fish resources have been diminishing because of water pollution, over-fishing and other human activities. Sustainable development is the key to healthy marine economy, which depends on good marine ecological environment. In this study we evaluated the offshore surface water quality of the Liaodong Bay by analyzing 18 samples collected in three consecutive seasons in 2013 including May (spring), August (summer), and October (autumn). We monitored the concentrations of six typical metallic pollutants (Cu, Pb, Zn, Cd, Hg, As) and employed the Nemerow Pollution Index and the Comprehensive Quality Index to evaluate the degree of heavy metal pollution. The concentrations of these heavy metals were highest in summer. The concentration of Pb did not meet the first-class seawater standard, which was 66.67% higher than the limit, however, all others complied with the first-class seawater standard. Concentrations of all heavy metals were below chronic safe concentration of organisms recommended by National Oceanic and Atmospheric Administration (NOAA) except for Cu. The Nemerow Pollution Index of the offshore surface seawater of the Liaodong Bay was in the range of 0.43-2.37, which was lower than 2.6, thus the pollution degree in 2013 was determined to be clean to slightly polluted. The Comprehensive Quality Index was between 0.39-0.97, which was lower than 1.0, therefore the water environment was acceptable and ranked as clean to slight clean. There were three areas that were relatively heavily polluted, including the Suizhong offshore area, north of the Liaodong Bay estuary area, and the Fuzhou Bay and Jinzhou Bay offshore areas.
Human activities have aggravated the offshore ecologic environment in the Liaodong Bay and endangered aquatic bioresources in these areas. The Liaodong Bay used to be an important fishing ground and the habitat of a variety of fish species such as Larimichthys polyactis, Trichiurus lepturus, and Fenneropenaeus chinensis. However, in recent years the fish resources have been diminishing because of water pollution, over-fishing and other human activities. Sustainable development is the key to healthy marine economy, which depends on good marine ecological environment. In this study we evaluated the offshore surface water quality of the Liaodong Bay by analyzing 18 samples collected in three consecutive seasons in 2013 including May (spring), August (summer), and October (autumn). We monitored the concentrations of six typical metallic pollutants (Cu, Pb, Zn, Cd, Hg, As) and employed the Nemerow Pollution Index and the Comprehensive Quality Index to evaluate the degree of heavy metal pollution. The concentrations of these heavy metals were highest in summer. The concentration of Pb did not meet the first-class seawater standard, which was 66.67% higher than the limit, however, all others complied with the first-class seawater standard. Concentrations of all heavy metals were below chronic safe concentration of organisms recommended by National Oceanic and Atmospheric Administration (NOAA) except for Cu. The Nemerow Pollution Index of the offshore surface seawater of the Liaodong Bay was in the range of 0.43-2.37, which was lower than 2.6, thus the pollution degree in 2013 was determined to be clean to slightly polluted. The Comprehensive Quality Index was between 0.39-0.97, which was lower than 1.0, therefore the water environment was acceptable and ranked as clean to slight clean. There were three areas that were relatively heavily polluted, including the Suizhong offshore area, north of the Liaodong Bay estuary area, and the Fuzhou Bay and Jinzhou Bay offshore areas.
2015, 36(1):124-131.
DOI: 10.11758/yykxjz.20150119
Abstract:
The inshore water areas are the major habitats and fishing grounds of many commercial species. Chinese inshore fisheries accounts for more than 90% of the total marine catches, and is an important resource of high-quality proteins for Chinese people. Currently the inshore fishery resources have been markedly declining due to the combination of overfishing and other excessive human activities (e.g. large-scale reclamation, pollution and mariculture). The sustainable production of many inshore fishery species has been impaired by adverse ecological change, such as the eutrophication-induced red tide and jellyfish bloom, and the fragmentation and defunctionalization of spawning and nursery grounds caused by the loss of wetlands. The recruitment of fishery populations is generally regulated by the interaction between the biological and physical processes in marine ecosystems which can be largely affected by the changes in environmental factors. To better understand the succession of marine ecosystem and sustainable yield of marine fishery populations, it is crucial to investigate how environmental changes affect the habitats and recruitment of fishery populations, especially at their early life stages. In this paper we reviewed literatures regarding these topics and analyzed the current situation of Chinese inshore fishery and the relevant problems of inshore ecosystems. We proposed and discussed four promising topics in future study: 1) fundamental and long-term changes in spawning and nursery grounds of fishery populations; 2) recruitment of fishery populations and the environmental driving forces; 3) adaptive strategies of fishery populations to environmental changes; and 4) evaluation of the effects of environmental changes on fishery population dynamics. These prospective studies are expected to provide essential knowledge that helps with the conservation of fishery habitats and resources as well as the improvement of sustainable development of inshore fisheries in China.
The inshore water areas are the major habitats and fishing grounds of many commercial species. Chinese inshore fisheries accounts for more than 90% of the total marine catches, and is an important resource of high-quality proteins for Chinese people. Currently the inshore fishery resources have been markedly declining due to the combination of overfishing and other excessive human activities (e.g. large-scale reclamation, pollution and mariculture). The sustainable production of many inshore fishery species has been impaired by adverse ecological change, such as the eutrophication-induced red tide and jellyfish bloom, and the fragmentation and defunctionalization of spawning and nursery grounds caused by the loss of wetlands. The recruitment of fishery populations is generally regulated by the interaction between the biological and physical processes in marine ecosystems which can be largely affected by the changes in environmental factors. To better understand the succession of marine ecosystem and sustainable yield of marine fishery populations, it is crucial to investigate how environmental changes affect the habitats and recruitment of fishery populations, especially at their early life stages. In this paper we reviewed literatures regarding these topics and analyzed the current situation of Chinese inshore fishery and the relevant problems of inshore ecosystems. We proposed and discussed four promising topics in future study: 1) fundamental and long-term changes in spawning and nursery grounds of fishery populations; 2) recruitment of fishery populations and the environmental driving forces; 3) adaptive strategies of fishery populations to environmental changes; and 4) evaluation of the effects of environmental changes on fishery population dynamics. These prospective studies are expected to provide essential knowledge that helps with the conservation of fishery habitats and resources as well as the improvement of sustainable development of inshore fisheries in China.
2015, 36(6):8-16.
DOI: 10.11758/yykxjz.20150602
Abstract:
In this study we analyzed the spatial distribution and the diversity of the fishery species in the Yangtze River estuary and its adjacent waters, and explored how they are affected by the environmental factors, based on the bottom trawl survey data collected from August 2012 to May 2013. A total of 114 fishery species (17 orders, 66 families and 90 Genera) were collected, including 58 fish species (12 orders, 36 families and 50 Genera), the richest species was found in Perciformes (26 species), 49 crustacean species (2 orders, 25 families and 33 Genera) and 7 cephalopod species (3 orders, 5 families and 6 Genera). The dominant species were season-dependent, whereas Harpodon nehereus was the only all-year-round dominant species. The average catch per haul was highest in autumn (29.20 kg/h·net), followed by that in spring (17.95 kg/h·net), summer (14.60 kg/h·net), and the least in winter (10.15 kg/h·net). Generally the demersal fish and crustaceans constituted the majority in the catch in all seasons, and the percentage of the pelagic fish was only slightly higher in spring (20.1%). The diversity indices of fishery species in spring and summer were higher than those in autumn and winter. The migration index and alternate index of fishery species were higher in spring (163) and summer (176), which meant the higher stability in fisheries community in the Yangtze River estuary. The migration index was close to 0 in summer (6) and winter (–5), suggesting that the immigration and emigration of the fishery species were in a state of balance. The number of fishery species and total catches were significantly positively correlated with the catches of the demersal fish and the crustaceans respectively in all seasons (P<0.01). The number of fishery species in autumn was positively correlated with both the sea surface temperature (P<0.05) and the water depth (P<0.01). These results showed a trend of increase in the low-valued species in the Yangtze River estuary and the adjacent waters. Our study suggested that there were significant seasonal variations in the structure of the fishery resource, and that the number of fishery species, the total catches and the diversity indices were highly related to the sea surface temperature and water depth.
In this study we analyzed the spatial distribution and the diversity of the fishery species in the Yangtze River estuary and its adjacent waters, and explored how they are affected by the environmental factors, based on the bottom trawl survey data collected from August 2012 to May 2013. A total of 114 fishery species (17 orders, 66 families and 90 Genera) were collected, including 58 fish species (12 orders, 36 families and 50 Genera), the richest species was found in Perciformes (26 species), 49 crustacean species (2 orders, 25 families and 33 Genera) and 7 cephalopod species (3 orders, 5 families and 6 Genera). The dominant species were season-dependent, whereas Harpodon nehereus was the only all-year-round dominant species. The average catch per haul was highest in autumn (29.20 kg/h·net), followed by that in spring (17.95 kg/h·net), summer (14.60 kg/h·net), and the least in winter (10.15 kg/h·net). Generally the demersal fish and crustaceans constituted the majority in the catch in all seasons, and the percentage of the pelagic fish was only slightly higher in spring (20.1%). The diversity indices of fishery species in spring and summer were higher than those in autumn and winter. The migration index and alternate index of fishery species were higher in spring (163) and summer (176), which meant the higher stability in fisheries community in the Yangtze River estuary. The migration index was close to 0 in summer (6) and winter (–5), suggesting that the immigration and emigration of the fishery species were in a state of balance. The number of fishery species and total catches were significantly positively correlated with the catches of the demersal fish and the crustaceans respectively in all seasons (P<0.01). The number of fishery species in autumn was positively correlated with both the sea surface temperature (P<0.05) and the water depth (P<0.01). These results showed a trend of increase in the low-valued species in the Yangtze River estuary and the adjacent waters. Our study suggested that there were significant seasonal variations in the structure of the fishery resource, and that the number of fishery species, the total catches and the diversity indices were highly related to the sea surface temperature and water depth.
2014, 35(4):1-6.
DOI: 10.11758/yykxjz.20140401
Abstract:
In this study we evaluated the biomass and distribution of Sthenoteuthis oualaniensis in South China Sea based on the data collected by Bdstar Navigation fishery information collection network that was mounted on the light falling net vessels. Considering the operation process of the light falling vessel, we built a light fishing stock assessment model and introduced a probability function to calculate the sweeping area and the biomass of S. oualaniensis. We then used kriging method to predict the density of S. oualaniensis and the CPUE. We subsequently generated a map of the distribution of S. oualaniensis and estimated the total biomass and the allowable catch. Our analysis showed that S. oualaniensis were widely distributed in South China Sea with high density (4 t/km2) in the area of 110.5°–111.5°E, 11°–12°N and 115.5°–116.5°E, 9.5°–11.5°N; in the area of 112°–112.5°E, 14.5°–15°N and 113°–115°E, 15°–16.5°N, the value of CPUE was as high as 1 kg/(kW•d•km2). The results of Kriging interpolation suggested that in the area of 108°–118°E, 9°–20°N there was a biomass of 2.05 million tons and an allowable catch of 994,000 tons in 359 fishing areas. The annual allowable catch could be 392,000 tons in 105 fishing areas inferred from CPUE. We assessed that there were 630,700 tons of S. oualaniensis in the area of Nansha Islands and it could be one of the future target species in the deep-sea fisheries. Here we only provided a crude estimate because all the parameters in our model were obtained by the sample vessels. To make an accurate estimate, further investigation will be needed on fishing vessels and fishing ground. It was found that the enhanced machine and light power did not necessarily increase the fishing efficiency. Although a higher light power could enlarge the illuminated area, davits could not support a larger falling net. Moreover, our model could also be used to assess the light arrangement, practice distance, and cost effectiveness in light fisheries.
In this study we evaluated the biomass and distribution of Sthenoteuthis oualaniensis in South China Sea based on the data collected by Bdstar Navigation fishery information collection network that was mounted on the light falling net vessels. Considering the operation process of the light falling vessel, we built a light fishing stock assessment model and introduced a probability function to calculate the sweeping area and the biomass of S. oualaniensis. We then used kriging method to predict the density of S. oualaniensis and the CPUE. We subsequently generated a map of the distribution of S. oualaniensis and estimated the total biomass and the allowable catch. Our analysis showed that S. oualaniensis were widely distributed in South China Sea with high density (4 t/km2) in the area of 110.5°–111.5°E, 11°–12°N and 115.5°–116.5°E, 9.5°–11.5°N; in the area of 112°–112.5°E, 14.5°–15°N and 113°–115°E, 15°–16.5°N, the value of CPUE was as high as 1 kg/(kW•d•km2). The results of Kriging interpolation suggested that in the area of 108°–118°E, 9°–20°N there was a biomass of 2.05 million tons and an allowable catch of 994,000 tons in 359 fishing areas. The annual allowable catch could be 392,000 tons in 105 fishing areas inferred from CPUE. We assessed that there were 630,700 tons of S. oualaniensis in the area of Nansha Islands and it could be one of the future target species in the deep-sea fisheries. Here we only provided a crude estimate because all the parameters in our model were obtained by the sample vessels. To make an accurate estimate, further investigation will be needed on fishing vessels and fishing ground. It was found that the enhanced machine and light power did not necessarily increase the fishing efficiency. Although a higher light power could enlarge the illuminated area, davits could not support a larger falling net. Moreover, our model could also be used to assess the light arrangement, practice distance, and cost effectiveness in light fisheries.
2014, 35(4):7-12.
DOI: 10.11758/yykxjz.20140402
Abstract:
In this study, we examined the phytoplankton community in the artificial reef areas of Laoshan Bay, and analyzed the relationships between phytoplankton and environment factors. Hence we provided references for the construction and evaluation of artificial reefs. The data and water samples were collected from four surveys in three artificial reef areas (Fengshan, Yangkou and Gangdong) of Laoshan Bay from March to December in 2011. By using Primer 5.0, we calculated the Shannon-Wiener, Margalef and Pielou of the phytoplankton community. We monitored the quarterly changes of phytop¬lankton community with cluster analysis, and applied Canonical Correspondence Analysis (CCA) to explore the relationship between phytoplankton species and the environmental factors using Canoco 4.5. In four surveys we identified a total of 69 species with microscope. We found that the dominant species was Skeletonema costatum in March, September and December, and it was Navicula spp in June. The density of phytoplankton in December was 49.78×105 cell/m3, which was the lowest in this survey. The density of phytoplankton in September was up to 408.65×105 cell/m3, which was the highest among all months. Shannon-Wiener and Margalef varied from 2.034 to 2.83, and from 5.27 to 7.25 respectively, both of which reached the maximum in September and the minimum in December. The range of Pielou was 0.580.78, and it reached the maximum in June and the minimum in December. According to the cluster analysis, the degree of similarity between March and June was 43.02%, and it was up to 42.38% between September and December. The species-environment bi-plots were drawn based on the results of CCA. The results showed that phosphate, temperature and silicate were the most important factors that influenced the distribution of phytoplankton species.
In this study, we examined the phytoplankton community in the artificial reef areas of Laoshan Bay, and analyzed the relationships between phytoplankton and environment factors. Hence we provided references for the construction and evaluation of artificial reefs. The data and water samples were collected from four surveys in three artificial reef areas (Fengshan, Yangkou and Gangdong) of Laoshan Bay from March to December in 2011. By using Primer 5.0, we calculated the Shannon-Wiener, Margalef and Pielou of the phytoplankton community. We monitored the quarterly changes of phytop¬lankton community with cluster analysis, and applied Canonical Correspondence Analysis (CCA) to explore the relationship between phytoplankton species and the environmental factors using Canoco 4.5. In four surveys we identified a total of 69 species with microscope. We found that the dominant species was Skeletonema costatum in March, September and December, and it was Navicula spp in June. The density of phytoplankton in December was 49.78×105 cell/m3, which was the lowest in this survey. The density of phytoplankton in September was up to 408.65×105 cell/m3, which was the highest among all months. Shannon-Wiener and Margalef varied from 2.034 to 2.83, and from 5.27 to 7.25 respectively, both of which reached the maximum in September and the minimum in December. The range of Pielou was 0.580.78, and it reached the maximum in June and the minimum in December. According to the cluster analysis, the degree of similarity between March and June was 43.02%, and it was up to 42.38% between September and December. The species-environment bi-plots were drawn based on the results of CCA. The results showed that phosphate, temperature and silicate were the most important factors that influenced the distribution of phytoplankton species.
2014, 35(2):22-29.
DOI: 10.11758/yykxjz.20140204
Abstract:
Collecting acoustic data from fishing vessels is an important trend in fishery resources study, yet the quality of the data may be seriously compromised by inter-instrument acoustic interferences due to the lack of signal synchronization apparatus for onboard acoustic instruments. In order to fully use the contaminated acoustic data, a method of extracting swarm signals from echogram with strong interference was established based on the relevant modules in the Echoview,an acoustic data post-processing software. The methods were then applied to the acoustic data on Antarctic krill collected onboard a fishing vessel operated around South Orkney Islands during February 2011, and the interference was effectively removed from the echogram. Distinct diel vertical migration was observed in the krill swarms. The geometrical center of the krill swarms was distributed in layers with a mean depth of 77.4 m and a mean thickness of 41.2 m in daytime, while the swarms tended to migrate upward nocturnally at a mean depth of 34.9 m and a mean thickness of 8.8 m.
Collecting acoustic data from fishing vessels is an important trend in fishery resources study, yet the quality of the data may be seriously compromised by inter-instrument acoustic interferences due to the lack of signal synchronization apparatus for onboard acoustic instruments. In order to fully use the contaminated acoustic data, a method of extracting swarm signals from echogram with strong interference was established based on the relevant modules in the Echoview,an acoustic data post-processing software. The methods were then applied to the acoustic data on Antarctic krill collected onboard a fishing vessel operated around South Orkney Islands during February 2011, and the interference was effectively removed from the echogram. Distinct diel vertical migration was observed in the krill swarms. The geometrical center of the krill swarms was distributed in layers with a mean depth of 77.4 m and a mean thickness of 41.2 m in daytime, while the swarms tended to migrate upward nocturnally at a mean depth of 34.9 m and a mean thickness of 8.8 m.
