Marine Fisheries

Analysis of genetic diversity of Siniperca scherzeri population in Qingshui River based on mitochondrial Cytb and D-Loop sequences

2022, 44(6): 657.

Abstract ( 150 )

PDF (2949KB) ( 482 )

Analysis of genetic diversity of Siniperca scherzeri

population in Qingshui River based on

mitochondrial Cytb and D-Loop sequences

MA Zhifang1, PAN Qiuzhi1, AN Miao1, LI Shan2, HUANG Sheng1, YU Ke1
(1. College of Animal Science, Guizhou University, Guiyang550025, China;
2.Guizhou Vocational College of Agriculture, Guiyang551499,China)

Abstract: Qingshui River is located in the northern part of the eastern section of Miaoling Mountain range, which is the slope of the transition from the YunnanGuizhou Plateau to the hills of Hunan and Guangxi, and it is the upper reaches of Yuanjiang River in Dongting Lake Water System of the Yangtze River basin, and it is also the second largest river in Guizhou Province. In order to analyze the genetic diversity and population genetic structure of wild Siniperca scherzeri population in Qingshui River basin, and to provide a theoretical basis for conservation management of the wild resources, we have set up a total of ten sampling sites in the upper, middle and lower reaches of Qingshui River and collected 287 individuals of wild Siniperca scherzeri. Genetic diversity and phylogenetic relationshihs of 287 wild Siniperca scherzeri were investigated based on mitochondrial cytochrome b (Cytb) and control region (DLoop) sequences. The completed mt DNA Cytb gene sequence (1 141 bp) and partial DLoop control region sequence (840841 bp) of wild Siniperca scherzeri were PCR amplified, sequenced, and analyzed. The preliminary findings were as follows: 1) The average contents of A, T, G and C in Cytb sequences were 24.3%, 27.3%, 15.5% and 32.4%, respectively, and the corresponding contents off our bases in DLoop sequences were 34.0%, 30.1%, 15.8% and 20.1%, respectively. Meanwhile, the average content of A+T was 51.6% (Cytb) and 64.1% (DLoop) respectively, both higher than the average C+G content of 48.4% (Cytb) and 35.9% (DLoop), and the proportion of base G was the lowest, respectively, the data showed a bias against G, and the proportion of A to T in Cytb and DLoop gene sequence was a little different. In addition, 23 variation sites were detected in Cytb gene sequences, of which 16 were parsimony informative sites and 7 were singleton variable sites, no base insertions or deletions, and a base conversion/reversal ratio of 4.60. While 44 variation sites were detected in DLoop gene sequences, of which 39 were parsimony informative sites and 5 were singleton variable sites, no base insertions or deletions, 3 base deletions, no base insertions and a base conversion/reversal ratio of 10.19. 2) 25 haplotypes were defined in Cytb gene sequences, the haplotype diversity of 3 populations (UQ, MQ and LQ) ranged from 0.793±0.037 to 0.829±0.024, and the nucleotide diversity ranged from 0.0019±0.0001 to 0.0021±0.0001, the average haplotype diversity and nucleotide diversity were 0.821 ± 0.018 and 0.0020 ± 0.0001, respectively, the average number of nucleotide differences was 2.311. At the same time, 43 haplotypes were identified in DLoop gene sequences, the haplotype diversity of 3 populations (UQ, MQ and LQ) ranged from 0.884±0.031 to 0.921±0.017, and the nucleotide diversity ranged from 0.0074±0.0005 to 0.0091±0.0004, the average haplotype diversity and nucleotide diversity were 0.919±0.009 and 0.00831 ± 0.00025, respectively, the average number of nucleotide differences was 6.968. The genetic diversity of 3 populations showed a decreasing trend of UQ>MQ>LQ in DLoop gene, while Cytb gene had the highest genetic diversity in MQ, with the order of size being MQ>LQ>UQ.3) Within populations, the genetic distance decreased from 0.0092±0.0017 to 0.0074±0.0015 within UQ, MQ and LQ populations in DLoop gene, and the degree of genetic variation became progressively lower. However, Cytb gene had the highest variation in MQ, with the same degree of variation in UQ and LQ. Among populations, the greatest genetic differences were found between UQ and MQ in DLoop gene, and the smallest between MQ and LQ, while Cytb gene differed to a similar extent between the two populations of three populations. And the mean genetic distances within the population were 0.0021 and 0.0087 in DLoop and Cytb genes, respectively. Fst values among 3 populations were not significant both in Cytb and DLoop genes. The level of gene flow between UQ and LQ of Qingshui River was higher，and the individuals’exchanges were frequent. Analysis of molecular variance (AMOVA) demonstrated that variation in individuals within the population accounted for 97.54% (Cytb) and 97.32%(DLoop) of total variation, genetic differentiation among populations was not significant. 4) The results of phylogenetic analysis and haplotype evolution network showed that the haplotypes of both Cytb and DLoop genes clustered into two branches, and haplotypes of both branches distributed in the upper, middle and lower reaches of the river, there was no clear geographical pattern of distribution. And it had the closest evolutionary relationship with Siniperca scherzeri from Yangtze River (Dongting Lake water system) according to Cytb phylogenetic study. 5) Tajima’ s D and Fu’ s Fs values of wild Siniperca scherzeri were -0.9553 and showed extremely significant difference (P<0.01) in Cytb gene, and mismatch distribution analysis showed a poisson distribution, the results of neutral test and nucleotide mismatch analysis in Cytb gene showed that there had been a significant population expansion event recently, the equation estimated that the population expansion of wild Siniperca scherzeri population in Qingshui River occurred 0.176 million years ago. In contrast, the DLoop gene was consistent with the hypothesis of neutral evolution and no population expansion was detected. In summary, these findings indicated that wild Siniperca scherzeri population in Qingshui River showed no obvious genetic differentiation among populations, and had higher genetic diversity, as high haplotype diversity and low nucleotide diversity. The results can complement basic genetic diversity background of wild Siniperca scherzeri in Yangtze River basin, and will be usefully applied to scientific strategies for the protection, sustainable development and commercial utilization of germplasm resources of wild Siniperca scherzeri in Qingshui River.

Keywords: Siniperca scherzeri; genetic diversity ; Cytb; DLoop

Related Articles | Metrics

Study on age structure and growth characteristics of Coilia mystus spawning population in the Yangtze Estuary

2022, 44(6): 670.

Abstract ( 134 )

PDF (2158KB) ( 443 )

Study on age structure and growth characteristics of

Coilia mystus spawning population in the Yangtze Estuary

HUANG Chengwei, WAN Rong, LI Zengguang, HU Yongbin
(Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources, National Engineering Research
Center for Oceanic Fisheries,College of Marine Sciences,Shanghai Ocean University, Shanghai201306, China)

Abstract: The main purpose of this study is to explore the relationship between the age and growth of Coilia mystus breeding population. C. mystus is one of most important economic fish in the Yangtze Estuary, whose resources have collapsed in recent years. Its main distribution area is in the Western Pacific Ocean, including the waters of China, Korean Peninsula and Japan. C. mystus is a semianadromous migratory fish, which usually lives in the coastal areas and migrates to estuarine area during reproduction. There are three ecological groups of C. mystus in the southeastern coast of China, namely the Yangtze River type, the Minjiang type and the Pearl River type. This study focused on the Yangtze River type, whose mature breeding colonies migrated from the coastal shallow sea clusters to the brackish and fresh water areas of the Yangtze Estuary near the Chongming Island to spawn and form fish floods. In the 1980s, the average annual output of C. mystus accounted for about 48.6% of the total output of fish and shrimp aquatic products in the Yangtze River Estuary. However, due to water pollution, overfishing and other factors in recent years, C. mystus resources have declined seriously and fishing season has failed to form with a trend of miniaturization and younger age, indicating that the Yangtze River population has collapsed. Our literature search showed that there had no relevant study on the age structure and growth characteristics of the breeding population for C. mystus in the Yangtze River Estuary since 2016. It is urgent to carry out relevant research about the resource assessment and conservation work for this species in the Yangtze River Estuary. Therefore, this paper used a spawning population of C. mystus collected from the Yangtze River Estuary in May, June and July 2018 and May 2019, and 194 samples were collected from the catches to study their age structure and growth characteristics. It is expected to provide basic data for the evaluation of the effect of comprehensive ban on fishing in the Yangtze River on the protection and management of Coilia mystus in the Yangtze Estuary. The results showed that the age structure was from 1 to 3 years old, among which age1 and age2 individuals were the dominant group, accounting for 82.48% of the total number of samples. This study and most other studies based on otolith age identification methods showed that there were 35yearold individuals in the breeding population of the Yangtze River Estuary, among which 12yearold group was the dominant group, accounting for almost 80% of all individuals. Body length ranged from 69 mm to 192 mm and body weight ranged from 1.5 g to 30.3 g. The average body length was (128.87±25.26) mm and the average body mass was (9.90±6.61) g. The relationship between body length and body weight was W=2×10-6L3.17. The asymptotic body length L∞ and asymptotic body mass W∞ in the growth equation of body length and body weight were 212.33 mm and 48.22 g, respectively. The growth coefficient k was 0.43 and the theoretical growth starting age t0 was -0.88. Male C. mystus tended to have uniform growth rate (b =2.87), while female C. mystus tended to have allallic growth rate (b =3.31). The age of inflection of body weight growth curve was 1.81 years old, and the length and body weight at the age of inflection were 145.44 mm and 14.52 g, respectively. Compared with the results of previous studies, both body length of C. mystus at inflection age and asymptotic body length in the Yangtze Estuary increased in recent years, indicating that the trend of miniaturization might have slowed down. However, whether the results of this study indicated that the trend of individual miniaturization in the Yangtze River Estuary in recent years might be effectively curbed remains to be verified by further data monitoring, and the reasons for this need to be further explored. The surface water temperature in the Yangtze Estuary during the flood season is one of the environmental factors that affect the reproductive characteristics of Coilia mystus in the Yangtze Estuary. After the water temperature rises, the fullness of the reproductive population and the weight of gonads of Coilia mystus decrease. The reason may be that the increase of temperature in the water environment leads to the enhanced metabolism of fish, the slowdown of nutrient accumulation in the body, and finally affects the maturation of their population. The surface water temperature in the waters of the Yangtze River Estuary from April to June showed an overall increasing trend from 1982 to 2014, and there was a modal shift around 1997, which meant that after 1997 the average surface water temperature in the waters of the Yangtze River Estuary from April to June was higher than that of previous years. The average rise was about 2℃, and it was significantly negatively correlated with the total catch of Coilia mystus and the catch of a single ship during the whole flood season. Further research is needed on the response of changes in biological characteristics (such as individual miniaturization) to environmental factors such as water temperature. The response law of the age structure and growth characteristics of C. mystus reproductive population needs to be further studied, under the dual effects of environmental changes and fishing ban measures in the Yangtze Estuary, the results of this study can be used as background information on the biological characteristics of C. mystus in the Yangtze Estuary before the implementation of comprehensive fishing ban, and can be of reference value for further evaluation of the effect of the fishing ban in the Yangtze River.

Keywords: Coilia mystus; age; growth; Yangtze Estuary

Related Articles | Metrics

Distinguishing wild from released juvenile Sparus macrocephalus with otolith chemical signatures

2022, 44(6): 680.

Abstract ( 135 )

PDF (2221KB) ( 450 )

Distinguishing wild from released juvenile

Sparus macrocephalus with otolith chemical signatures

ZHANG Yi，ZHANG Hui，JIANG Yazhou，LING Jianzhong，LIU Zunlei，LI Shengfa
(1.Key Labortory of East China Sea Fishery Resources Exploitation and Utilization , Ministry of Agriculture and Rural
Affairs, East China Sea Fisheries Research Institute,Chinese Academy of Fisheries Sciences,Shanghai200090,China)

Abstract: A central goal of stock enhancement is to increase species abundance and potential harvest by supplementing recruitment of wild populations. The black sea bream Sparus macrocephalus represents very important recreational fishery along China’s coastline and is stocked in coastal bays to enhance natural fish abundance.To distinguish aquacultured fish from wild population is essential for evaluating the potential stock enhancement. Otolith chemistry signatures are regarded as natural tags to distinguish wild from released Sparus macrocephalus.

From May to June 2019, before the enhancement and releasing of Sparus macrocephalus in Xiangshan Bay, juvenile samples were collected with gill nets, and water temperature and salinity of sampling sites were recorded. The body length of collected Sparus macrocephalus was 3.053.89 cm with a sample size of 20. The samples captured were identified to be wild population according to sampling time and body length. During the rearing of Sparus macrocephalus, fresh water was pumped into the seawater every day to adjust the salinity of cultured seawater, and the salinity of cultured seawater was kept at a suitable range of 1825 for at least 30 days. Thirty cultured fish were collected. In August 2020, adult Sparus macrocephalus samples were collected from Xiangshan Bay, with a body length of 10.619.5 cm, and the sample size was 20. Samples of natural seawater, fresh water and cultured seawater were collected randomly for 5 days, filtered by microporous filter membrane (0.45 μm) to remove impurities, collected and stored in plastic bottles, and brought back to the laboratory for detection of Sr and Ba concentrations. From each individual, sagittal otolith pairs were extracted from the fish, cleaned with H2O2, rinsed with 18.2 MΩ MQ water and dried. Sagittae were embedded in araldite resin, ground on a sagittal plane to expose their primordium and polished with diamond papers of decreasing grain diameter. Finally, the otoliths were double rinsed with 18.2 MΩ MQ water, dried prior to LAICPMS analysis. A continuous linear transect was taken across the otoliths passing through the core to the edge at a speed of 2 μm·s-1. Five elements (Sr,Ba,Mn,Mg,Ca) were initially monitored.

The salinity of natural seawater in Xiangshan Bay was 2527, and the surface water temperature was 1822 ℃. The salinity of cultured sea waterwas about 2 degrees lower than that of natural seawater after pumping fresh water. The Sr concentrations of natural seawater and cultured seawater were (5 428.67±72.93) μg·L-1 and (4 377.59±52.85) μg·L-1, respectively. Ba concentration was (27.33±1.39) μg·L-1, (41.97±1.62) μg·L-1; Ca concentration was (342.6±2.57) mg·L-1, (289.2±2.78) mg·L-1. The Sr/Ca ratios of natural seawater and cultured seawater were (7.2±0.09), (6.96±0.08) mmol·mol-1, and the Ba/Ca ratios were (23.3±1.2), (42.3±1.6) μmol·mol-1, respectively. The Sr/Ca ratio and Ba/Ca ratio of cultured seawater were about 0.96 and 1.82 times of those of natural seawater. The concentration of Ba in cultured seawater was significantly higher than that in natural seawater (P<0.05).

The Sr/Ca and Ba/Ca ratios of otoliths of cultured and wild Sparus macrocephalus were measured from the core to the edge. The Sr/Ca ratios of cultured and wild Sparus macrocephalus were 1.52.0 mmol·mol-1, and the Sr/Ca ratios had little fluctuation. The Ba/Ca ratio of cultured Sparus macrocephalus was 1025 μmol·mol-1, and the Ba/Ca ratio of wild Sparus macrocephalus was 38 μmol·mol-1. The fluctuation of Ba/Ca ratio in cultured Sparus macrocephalus otolith was obvious, but the fluctuation of Ba/Ca ratio in wild Sparus macrocephalus otolith was relatively small. The results showed that there was no significant difference in Sr/Ca ratio between cultured and wild Sparus macrocephalus, but Ba/Ca ratio in cultured Sparus macrocephalus was significantly higher than that in wild. The otolith radius of cultured Sparus macrocephalus was about 400 μm.

The Sr/Ca ratio near the otolith core (CSr/Ca) of cultured and wild Sparus macrocephalus was (1.96±0.12) mmol·mol-1, (1.97±0.06) mmol·mol-1, respectively, and there was no significant difference between them (P>0.05). The Ba/Ca ratio of the otolith core (CBa/Ca) in cultured and wild Sparus macrocephalus was (16.09±6.23) μmol·mol-1 and (3.05±0.58) μmol·mol-1, respectively. CBa/Ca of cultured Sparus macrocephalus was significantly higher than that of wild(P<0.05). The mean Sr/Ca ratios(XSr/Ca) of whole otoliths of cultured and wild Sparus macrocephalus were (1.77±0.06),(1.82±0.07) mmol·mol-1, respectively, and there was no significant difference between them (P>0.05). The mean Ba/Ca ratios value (XBa/Ca) of cultured and wild Sparus macrocephalus were (16.96±2.02) μmol·mol-1 and (4.08±0.32) μmol·mol-1, respectively. The mean otolith Ba/Ca ratio (XBa/Ca) of cultured Sparus macrocephalus was significantly higher than that of wild(P<0.05). The coefficients of variation of Sr/Ca ratio (CVISr/Ca) of cultured and wild Sparus macrocephalus were 0.14±0.01 and 0.13±0.01, respectively, and there was no significant difference between them (P>0.05). The coefficients of variation of Ba/Ca ratio element (CVIBa/Ca) of cultured and wild Sparus macrocephalus were 1.26±0.3 and 0.69±0.15, respectively. The coefficient of variation of Ba/Ca ratio (CVIBa/Ca) of cultured Sparus macrocephalus was significantly higher than that of wild(P<0.05). CBa/Ca, XBa/Ca and CVIBa/Ca of the otolith core of cultured Sparus macrocephalus were significantly higher than those of wild(P<0.05).

According to the characteristics that cultured Sparus macrocephalus’s CBa/Ca, XBa/Ca and CVIBa/Ca were significantly higher than those of wild population, otolith Ba/Ca ratio can be used as a microchemical marker for the identification of released and wild Sparus macrocephalus. Original source discriminant analysis was conducted on 20 adult Sparus macrocephalus samples captured in Xiangshan Bay. The CBa/Ca near otolith cores of two Sparus macrocephalus were 15.56,10.33μmol·mol-1, respectively. And XBa/Ca within 400 μm from the core were 16.08,9.23 μmol·mol-1, and CVIBa/Ca were 1.96 and 1.62, respectively. CBa/Ca, XBa/Ca and CVIBa/Ca at the juvenile stage of two Sparus macrocephalus were significantly higher than those of the other samples. According to Ba/Ca marker, the discrimination of 20 adult Sparus macrocephalus caught in Xiangshan Bay showed that two Sparus macrocephalus were released.

Keywords: Sparus macrocephalus；otolith；Ba；microchemical marker；element analysis

Related Articles | Metrics

Impacts of aquaculture-derived organic matter sedimentation on the trophic characteristics of dominant polychaetes in Sansha Bay

2022, 44(6): 689.

Abstract ( 108 )

PDF (2132KB) ( 412 )

Impacts of aquaculture-derived organic matter sedimentation

on the trophic characteristics of dominant polychaetes in Sansha Bay

ZHANG Pengzhan1,2, FU Jing2, ZHOU Jin2
(1. College of Fisheries and Life Science, Shanghai Ocean University, Shanghai201306, China;
2. East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai200090, China)

Abstract: Sansha Bay, located in the northeast of Fujian Province, is a typical farming bay in China′s offshore. Aquaculture activities in the bay include cage farming of fish, raft farming of seaweeds, floating farming of abalone, and cage farming of Pseudosciaena crocea. In 2020, the production of P. crocea reached 179 000 tons in Sansha Bay, accounting for more than 70% of the total production of P. crocea in China. Cage farming is a kind of feeding aquaculture, which produces a considerable number of aquaculturederived organic matter (AOM), including waste feed and feces. AOM with higher nitrogen and phosphorus content is released into the environment in both dissolved and particulate form. Dissolved AOM is diluted and diffused by hydrodynamic action, and particulate AOM settles into the sediment. AOM in sediments is ingested by macrobenthos and affects material cycling and energy flow in ecosystems. Polychaetes (Annelida) are a relatively common group of macrobenthos. After settling into the sediment environment, AOM may be ingested by depositfeeding and omnivorous polychaetes, and the nutritional and ecological characteristics of polychaetes will change accordingly. Many studies have focused on the structure of benthic communities in Sansha Bay, and the effects of farming activities on the nutritional and ecological characteristics of macrobenthos have not been reported so far. To understand the benthic ecological and environmental effects of cage farming activities in Sansha Bay, stable carbon and nitrogen isotope ratios (δ13C and δ15N) with numerical model method were used to analyze the impacts of AOM sedimentation on the trophic characteristics of five numerical dominant macrobenthos, Onuphis eremita, Ophelina acuminata, Lumbrineris sp., Heteromastus filiformis and Sternaspis scutata. Potential food sources for polychaetes in Sansha Bay included waste feed, fecal matter, seaweeds (Laminaria japonica and Gracilaria lemaneiformis), particulate organic matter (POM), zooplankton, and benthic microalgae. Five stations were arranged on each section of three sampling transects of different hydrodynamic characteristics. Benthic species and their potential food sources were collected from September 24th to 29th, 2021. The sedimentary organic matter (SOM) samples were also sampled as a mixture of food sources. The δ13C and δ15N of these samples were analyzed.

The results showed that the δ13C and δ15N of potential food sources ranged from -25.51‰ to -12.71‰ and 3.30‰ to 12.91‰, respectively. The δ13C and δ15N of potential food sources showed significant differences, respectively (KruskalWallis test, P<0.001). The δ13C and δ15N of SOM ranged from -25.51‰ to -21.04‰ and 3.79‰ to 7.44‰, respectively. The δ13C and δ15N of SOM showed significant differences, respectively (KruskalWallis test, P<0.05) among three sampling transects. The δ13C and δ15N of POM ranged from -25.08‰ to -22.85‰ and 6.21‰ to 11.47‰, respectively. The δ15N of POM showed significant differences (KruskalWallis test, P<0.01) among three sampling transects. The values of δ13C and δ15N of L. japonica were (-14.61±2.01)‰ and (7.18±2.98)‰, respectively. The values of δ13C and δ15N of G. lemaneiformis were (-18.40±0.27)‰ and (11.60±1.29)‰, respectively. The values of δ13C and δ15N of zooplankton were (-18.17±0.36)‰ and (10.41±0.99)‰, respectively. The values of δ13C and δ15N of benthic microalgae were (-22.63±0.55)‰ and (4.86±1.46)‰, respectively. The values of δ13C and δ15N of waste feed were -(17.58±0.28)‰ and （11.27±0.32）‰, respectively. The values of δ13C and δ15N of fecal matter were （-20.31±1.42）‰ and （7.62±1.47）‰, respectively. The δ13C and δ15N of five dominant polychaetes ranged from -21.82‰ to -16.87‰ and 7.05‰ to 12.98‰, respectively. The δ13C and δ15N of O. eremita ranged from -20.97‰ to -16.87‰ and 9.15‰ to 12.98‰, respectively. The δ13C and δ15N of O. eremita showed significant differences, respectively (KruskalWallis test, P<0.01) among three sampling transects. The δ13C and δ15N of O. acuminata ranged from -18.84‰ to -17.39‰ and 9.76‰ to 10.34‰, respectively. The δ13C and δ15N of Lumbrineris sp. ranged from -19.84‰ to -18.20‰ and 10.36‰ to 12.53‰, respectively. The δ13C and δ15N of H. filiformis ranged from -20.20‰ to -19.20‰ and 10.03‰ to 11.38‰, respectively. The δ13C and δ15N of S. scutata ranged from -21.82‰ to -18.77‰ and 7.05‰ to 8.79‰, respectively. Trophic levels of five species showed significant differences (KruskalWallis test, P<0.001). Omnivorous polychaetes Lumbrineris sp. and O. eremita had the highest trophic levels (2.79 and 2.78, respectively), and depositfeeding polychaetes H. filiformis and O. acuminata had intermediate levels (2.62 and 2.41, respectively), and S. scutata was found at the lowest level (1.81). The δ13C and δ15N of G. lemaneiformis and zooplankton in Sansha Bay were close to those of benthic dominant species (difference<1‰), and the difference of δ13C between L. japonica and benthic dominant species (>4‰) was much higher than the fractionation coefficient of δ13C (about 1‰). G. lemaneiformis, zooplankton, and L. japonica were not the food sources of benthic dominant species in Sansha Bay. Bayesian stable isotope mixing models in R (SIMMR) package were used to estimate the proportional contribution of food sources (waste feed, fecal matter, benthic microalgae, and POM) to the five species. The results showed that AOM was an important food source for dominant polychaetes, contributing （68.4±17.2）%, （61.7±22.0）%, （54.9±13.4）%, （36.4±8.3）%, and （18.3±13.2）% to O. eremita, O. acuminata, Lumbrineris sp., H. filiformis, and S. scutata, respectively. The contribution of fecal matter was （35.0±13.2）%, （53.3±21.7）%, （35.9±16.4）%, （23.4±2.6）%, and （11.0±7.8）% to O. eremita, O. acuminata, Lumbrineris sp., H. filiformis, and S. scutata, respectively. The contribution of waste feed was （33.4±18.4）%, （8.4±7.4）%, （19.0±11.9）%, （13.0±5.6）%, and （7.3±5.4）% to O. eremita, O. acuminata, Lumbrineris sp., H. filiformis, and S. scutata, respectively. Benthic microalgae contributed to the diets of dominant polychaetes as well, contributing （22.5±15.6）%, （33.0±18.7）%, （30.7±15.0）%, （47.6±22.6）%, and （76.6±14.1)% to O. eremita, O. acuminata, Lumbrineris sp., H. filiformis, and S. scutata, respectively. POM contributed to the smallest diets of dominant polychaetes, contributing (9.1±5.1)%, (3.9±1.0)%, (14.4±8.9)%, (16.1±14.3)%, and (5.2±1.3)% to O. eremita, O. acuminata, Lumbrineris sp., H. filiformis, and S. scutata, respectively. In conclusion, the AOM originated from cage farming served as an important food source for macrobenthos in Sansha Bay, based on which it was concluded that the aquaculture activities showed significant effects on benthic ecological environment. The trophic ecological characteristics of macrobenthos in natural waters were affected by combined factors, and the food composition and feeding habits changed the trophic characteristics of macrobenthos in Sansha Bay.

Keywords: Sansha Bay； cage farming； benthic ecological effects； macrobenthos； polychaetes

Related Articles | Metrics

Study on bait contribution level of shellfish culture area in Yalu River Estuary

2022, 44(6): 700.

Abstract ( 64 )

PDF (2760KB) ( 400 )

Study on bait contribution level of shellfish culture area

in Yalu River Estuary

FU Jie1，SONG Lun1，YU Xuguang1，SONG Guangjun1，
SONG Guangjun1，WANG Kun1，LIU Yin2，LIU Suxuan2
（1. Key Laboratory of Marine Biological Resources and Ecology,Liaoning Ocean and Fisheries Science
Research Institute, Dalian Liaoning116023, China； 2. Dalian Ocean University, Dalian Liaoning116023, China）

Abstract: The Yalu River Estuary of Dandong of Liaoning Province is the main breeding area for the edible saltwater shellfish Ruditapes philippinarum. The breeding area is 45 000 hectares, and the annual production reaches 240 000 tons. The production accounts for 20% of the total production in Liaoning Province, and 6% of the national total production, making a great contribution to fishery carbon sink. However, in recent years, the culturing of Ruditapes philippinarum has faced with some problems, including reduced plumpness, prolonged growth cycle, and increased occurrence of diseases and mortality. Preliminary analysis showed that deterioration of the strains and variations in ecological conditions both contributed to the issue, which could be a complex systematic process. In this paper we studied the process by analyzing the bait contribution level to the shellfish in the living space.

There is feeding selectivity on the size of microalgae particles for filterfeeding shellfish. Ruditapes philippinarum prefers large sized microalgae. Attention should thus be paid to the variation in feeding capacity of large sized microalgae in seawater. Since most filterfeeding shellfish trapped microalgae larger than 10 μm, the dominant microalgal species were divided into two groups based on size, large microalgae larger than 10 μm, and small microalgae less than 10 μm, to investigate the feeding capacity of microalgae to shellfish. The size structure of microalgae was mainly analyzed using chlorophyll a fractionation method to roughly distinguish the biomass of different sized microalgae in previous studies. Due to the high interception rate of large pore filter membrane, the contribution of small sized microalgae to the feeding capacity to shellfish was seriously underestimated, which resulted in overestimated contribution of large sized microalgae. This further resulted in overestimated carrying capacity for shellfish in the study area. With the development of highthroughput sequencing technology, the number of sequences obtained through the molecular identification of eukaryotic microalgae can greatly improve the detection rate of small sized microalgae. The highthroughput sequencing technology could thus be used for the statistical analysis of the whole size structure of microalgae, and the characterization of biomass of effective feeding microalgae.

The monthly average feeding supply distribution of the Yalu River Estuary was plotted using the spatial inverse distance weight (IDW) model of GIS science for spatial interpolation. In the model, the feeding supply in unmeasured sea area was estimated through the index of the measured value of feeding supply of evenly distributed stations in measured sea area. The bait contribution index of different stations had weighted impact on the unknown stations, that the closer the distance was, the greater the impact would be.

Samples of filtered seawater were collected once a month from March to December at 16 stations in the Yalu River Estuary in 2020. We used highthroughput sequencing to identify eukaryotic microalgae. The microalgae fractionation was used to analyze the microalgae particle size structure. The IDW model was used in the plotting of feeding supply distribution by spatial interpolation. The results showed that the biomass of large microalgae accounted for 20%, 29%, 63% and 56% in spring, summer, autumn and winter, respectively. Large microalgae dominated in autumn and winter. Small microalgae dominated in spring and summer. The biomass of small microalgae accounted for 80%, 71%, 27% and 44% in spring, summer, autumn and winter, respectively. The overall feeding capacity of microalgae in the Yalu River Estuary was at a medium level, with the highest feeding capacity found in October and the lowest in July. The annual carrying capacity of Ruditapes philippinarum ranged from 41 g · m-2 to 338 g · m-2, with an average of 195 g · m-2, including 248 g · m-2 in spring, 117 g · m-2 in summer, 262 g · m-2 in autumn and 67 g · m-2 in winter. The carrying capacity was mainly contributed by spring and autumn. In the central part, the index was positively affected by chlorophyll a, inorganic nitrogen, nitrate, and total nitrogen, and negatively affected by salinity. At the east part, the index was positively affected by chlorophyll a, inorganic nitrogen to phosphorus ratio, inorganic nitrogen, nitrate and total nitrogen, and negatively affected by salinity. In general, on the spatial scale, the bait contribution index of Yalu River Estuary was mainly positively affected by chlorophyll a, inorganic nitrogen phosphorus ratio, inorganic nitrogen, nitrate and total nitrogen, and negatively affected by salinity. In terms of time series, the feeding index of each station was mostly affected by environmental factors in April and December, which was positively affected by total nitrogen, total phosphorus, COD, inorganic phosphorus, silicate, nitrate, nitrite, inorganic nitrogen, organic nitrogen and chlorophyll a, and negatively affected by pH, dissolved oxygen and inorganic nitrogen to phosphorus ratio.

The estimation of the carrying capacity of Ruditapes philippinarum in the study area was lower than that of previous studies. This was because the parameters of microalgae biomass were optimized in the nutrient dynamic model in this work. The biomass of large sized microalgae preferred by shellfish was selected for the estimation, which made the estimated carrying capacity of shellfish lower, while more in line with the reality. In addition, reduced size of microalgae in the breeding area possibly also contributed to the reduced shellfish carrying capacity. Further studies are needed to have a better understanding of the problems faced by the culturing of Ruditapes philippinarum. It is worth noting that the biomass of Karlodinium veneficum in this study area is high. This species is microdiatom, and it is also the main contributor to feeding power, which may affect the health quality and safety of shellfish.

Keywords: microalgae; Ruditapes philippinarum； bait contribution; size fraction; high throughput sequencing; Yalu River Estuary

Related Articles | Metrics

Cloning and expression of cck and cart4 genes of Pampus argenteus and effects of jellyfish intake #br# on their expression patterns

2022, 44(6): 710.

Abstract ( 89 )

PDF (6928KB) ( 414 )

Cloning and expression of cck and cart4 genes of

Pampus argenteus and effects of jellyfish intake

on their expression patterns

LIAN Shiya1,2， WANG Yabing2， WANG Qian2， CHEN Run2，
LI Yunkai3， ZHOU Junfang2， PENG Shiming2
(1.College of Fisheries and Life Science, Shanghai Ocean University, Shanghai201306, China;
2.East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai200090,
China; 3.College of Marine Sciences, Shanghai Ocean University, Shanghai201306, China)

Abstract: Silver pomfret (Pampus argenteus) is one of the most valued and attractive food fish species in China. In spite of important technical developments and intense research in Pampus argenteus, some bottlenecks still limit the expansion of its industry. One of these limitations is the lack of a suitable formulated diet for broodstock, which leads to the poor quality of gonads in cultured broodstock. This fish species has a distinct preference for preying on jellyfish, and their daily intake of Aurelia aurita exceeds their body weight by more than 10 times. The feeding patterns of wild pomfret in the East China Sea were studied using carbon and nitrogen stable isotope approaches, and jellyfish contributed up to 54% of Pampus argenteus diet. This indicated the fact that Pampus argenteus preferentially hunted jellyfish. Jellyfish is a conspicuous, yet longoverlooked component of pelagic marine systems, and it is widely distributed in the marine ecosystem and is an important fishery resource in China. It has long been regarded as a “dead end” in marine food webs due to its high water content (> 95%) and low content of highvalue nutrients. In recent years, studies have reported that the role of jellyfish in the marine food chain is seriously underestimated, and this finding is of great importance to the entire marine food chain system. In the last few years, the notion of gelatinous species as merely carbon sinks or trophic dead ends has become largely obsolete, and there is renewed interest in their trophic ecology. Recent data show that they may represent a qualitatively important resource for growth, reproduction and developmental processes, comprising the diet of more than 120 fishes and other medusivorous vertebrates, such as sea turtles. Some predators, like the ocean sunfish, may feed selectively on specific tissues within large jellyfish. According to research on fish digestion and jellyfish absorption efficiency, the digestion rate of salmon jellyfish is more than 20 times that of shrimp flesh. This is because jellyfish tissues can be rapidly digested and assimilated, and therefore, their diluted nutritive value can be compensated when consumed in sufficient supply and processed at a higher rate. Addition of jellyfish to the diet stimulates the digestion and absorption efficiency of the digestive tract. Adding jellyfish to Pampus argenteus feed can successfully boost their growth rate and Pampus argenteus can better digest and absorb jellyfish by altering the intestinal microbial makeup, indicating that this fish species possesses a system for digesting and absorbing nutrients from jellyfish. There is now overwhelming evidence suggesting that jellyfish has considerable nutritional content and their contribution to the energy budget of Pampus argenteus has been categorical. However, the underlying mechanism of the feeding preference behavior of Pampus argenteus to jellyfish is still unclear.

Cholecystokinin and cocaine and amphetamineregulated transcript proteinlike play important roles in animal feeding regulation. The cck gene is a key regulator of gastrointestinal function and an important satiety signal in vertebrates, including fish, and is involved in appetite regulation. The cart4 gene is thought to be an important neurotransmitter regulating body weight and food intake in rodents and humans. In this study, the full cDNA sequences of cck and cart4 genes of Pampus argenteus were cloned. The cck gene was 1 125 bp in length, 5′untranslated region (5′UTR) was 42 bp in length, and 3′UTR was 679 bp in length. It contained a 405 bp open reading frame (ORF), which encoded and synthesized a 134 aa protein and contained a characteristic sequence of a typical Cck family. The highest homology of Cck between Pampus argenteus and Micropterus salmoides was 87.59%, and the homology between Pampus argenteus and other fish was also higher than 67.88%. The phylogenetic tree results also showed that Cck between Pampus argenteus and Micropterus salmoides clustered in the same branch and had the closest genetic relationship. The cart4 gene was 865 bp in length, 5′UTR was 133 bp in length, and 3′UTR was 400 bp in length. It contained a 333 bp open reading frame (ORF), which encoded and synthesized a 110 aa protein, a signal peptide composed of 24 amino acids and a domain named CART. The highest homology of Cart4 between Pampus argenteus and Xiphias gladius was 91.82%, and the homology between Pampus argenteus and other fish was also higher than 63.06%. The phylogenetic tree results also showed that Cart4 between Pampus argenteus and Xiphias gladiu clustered in the same branch and had the closest genetic relationship. Realtime PCR was used to detect the expression levels of cck and cart4 genes in different tissues and the effects of jellyfish ingestion on the expression levels of cck and cart4 genes in different tissues. The results showed that the expression of cck gene was the highest in midgut of noeating jellyfish group (P<0.05), and the highest in the brain of eating jellyfish group (P<0.05). Compared with noeating group, the expression levels of brain, liver and kidney in jellyfish feeding group significantly increased (P<0.01), and the expression levels of muscle also slightly increased (P>0.05), while the expression levels of midgut, gill and gonad in jellyfish feeding group significantly decreased (P<0.01). The expression of cart4 gene was the highest in brain (P<0.05). Compared with nofeeding group, the expression level of jellyfish in brain significantly increased (P<0.01), but significantly decreased in midgut, gill, liver and muscle (P<0.01).

The results showed that jellyfish consumption resulted in a significant upregulation of cck and cart4 gene expression in the brain tissue of Pampus argenteus. It indicated that eating jellyfish would increase the satiety of Pampus argenteus. The expression levels of two genes in the intestinal tract were significantly downregulated, which might be due to the high intestinal congestion caused by the high water content in jellyfish. The results further confirmed that cck and cart4 genes played important roles in the regulation of feeding activities of Pampus argenteus.

Keywords: cck gene; cart4 gene; Pampus argenteus; feeding jellyfish; expression pattern

Related Articles | Metrics

Analysis of the molecular mechanism of brain tissue of Thamnaconus septentrionalis in response to density stress based on transcriptome sequencing

2022, 44(6): 725.

Abstract ( 97 )

PDF (4799KB) ( 432 )

Analysis of the molecular mechanism of brain

tissue of Thamnaconus septentrionalis in response

to density stress based on transcriptome sequencing

DUAN Xiaochen1，2, CHENG Qiqun1
（1.East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai200090, China;
2. School of Fisheries and Life Sciences, Shanghai Ocean University, Shanghai201306, China）

Abstract: Thamnaconus septentrionalis, usually called green fin puffer, is a small to median sized fish in family Monocanthidae, order Tetraodontiformes. It is mainly distributed in the coastal areas of China, Japan, and Korea. In China, it is widely distributed in the Bohai Sea, Yellow Sea, East China Sea, and Taiwan Strait. Among them, East China Sea is one of the most important distribution zones of T. septentrionalis. T. septentrionalis is a relatively common economic fish along the coastal areas of China. After nearly forty years of intensive exploitation, T. septentrionalis resources have declined rapidly, and can not meet the market demand to a great extent at present. Replacing “catching” with “culturing” is one of the most effective way to relieve the pressure of wild resources and ensure the market supply of T. septentrionalis.

High density is one of the most important limiting factors affecting the growth of fish. Density stress can intensify the competition for space, food, oxygen and other resources within the population, and affect gene expression and adaptability. Some studies show that crowding can significantly induce the immune response of fish, and longterm density stress can damage the immune capacity of fish. Under high density conditions, the composition of fatty acids of fish muscle changes, and the activity of lipid metabolic enzymes can be stimulated with up regulation significantly. Also, high density culture may result in a significant decrease in the activities of various digestive enzymes, which then can affect the immune capacity of organisms. Till now, the molecular response mechanism of brain tissue of T. septentrionalis to density stress has been still unclear.

Transcriptome refers to the collection of all transcripts in a cell under a certain physiological condition. It includes messenger ribonucleic acid (mRNA), ribosomal ribonucleic acid (rRNA), transfer ribonucleic acid (tRNA) and noncoding ribonucleic acid (ncRNA). Transcriptomics is a discipline that studies gene transcription and transcriptional regulation of all kinds of genes and pathways in all cells at the overall level. Transcriptomics is an important means to reveal the molecular mechanism in organisms. When performing transcriptome analysis, we can firstly carry out highthroughput sequencing on aquatic animals, further analyze the expression of genes, annotate the functions of genes, and make clear the expression of relevant genes under specific conditions based on highthroughput sequencing results. Transcriptome analysis has been widely used in studying the biology of some aquatic animals.

In order to understand the molecular response mechanism of the brain tissue of T. septentrionalis under density stress, explore the differentially expressed genes, clarify the regulatory mechanism of differentially expressed genes in the brain tissue of T. septentrionalis, and provide a scientific base for the future studies of intensive artficial aquacuture and molecular breeding of T. septentrionalis, we set up two culturing density groups, a mediumdensity group of 100 ind·m-3 , and a highdensity group of 500 ind·m-3. The brain tissue of the two densities of T. septentrionalis on the 25th and 50th day was obtained, respectively, and the transcriptome sequencing analysis of the brain tissue samples of T. septentrionalis was carried out by using Illumina sequencing platform. A total of 100.3 Gb of highquality sequencing data was obtained. Then, we treated the data in turn with some steps, i.e., quality control, comparison of the obtained data, difference analysis, GO （Gene Ontology）function annotation analysis, KEGG （Kyoto Encyclopedia of Genes and Genomes） function enrichment analysis, and trend analysis. To facilitate the the results, some codes were used in this study: CB means the brain tissue of the control group; D1B represented the brain tissue of the 100 ind·m-3 group on the 25th day; D2B was the brain tissue of the 500 ind·m-3 group on the 25th day; d1B represented the brain tissue of the 100 ind·m-3 group on the 50th day; d2B was brain tissue of the 500 ind·m-3 group on the 50th day. The results were as follows : In CBvsD1B, the expression of 197 genes were upregulated and 418 genes were downregulated; in CBvsD2B, the expression of 114 genes were upregulated and 301 genes were downregulated; in vsd1B, the expression of 317 genes were upregulated and 491 genes were downregulated; in CBvsd2B, the expression of 311 genes were upregulated and 608 genes were downregulated. 2) GO classification analysis showed that differentially expressed genes belonged to 44 categories of biological process, cellular component and molecular function. 3) KEGG enrichment analysis showed that the signal pathways related to the circadian rhythm were significantly enriched in the four different groups. 4) The trend analysis focused on signal pathways such as circadian rhythm, MAPK signaling pathway, calcium ion signaling pathway, and found that some key genes such as clock, cry, bmal1, npas2, bdnf, rps6ka, il1r1, htr5a, ryr2, and pln were differentially expressed in the brain tissue of T. septentrionalis. These differentially expressed genes may play key role in regulating the circadian rhythm and immune ability of T. septentrionalis, which can lay a foundation for studying the regulation mechanism of gene expression of related genes in brain tissue of T. septentrionalis under density stress.

Keywords: Thamnaconus septentrionalis; transcriptome; density stress; gene expression; brain

Related Articles | Metrics

Effect of glycerol monolaurate on lipid metabolism and liver function of Lates calcarifer

2022, 44(6): 736.

Abstract ( 116 )

PDF (2504KB) ( 411 )

Effect of glycerol monolaurate on lipid metabolism

and liver function of Lates calcarifer

ZHANG Hui1,2, Dong Hongbiao2, SUN Caiyun2,3, CHEN Jian4,
HUANG Congling5, LI Yong5, DUAN Yafei2, ZHANG Jiasong2
(1. Ocean College, Hebei Agricultural University, Qinhuangdao Hebei066000, China; 2. Key Laboratory of
South China Sea Fishery Resources Exploitation & Utilization of Mininstry of of Agriculture and Rural Affairs,
South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou510300, China;
3. National Demonstration Center For Experimental Fisheries Science Education, Shanghai Ocean University,
Shanghai201306, China; 4. Yangjiang Aquatic Product Technology Promotion Station, Yangjjiang Guangdong
529500, China; 5. Modern Agricultural Development Center of Zhuhai City, Zhuhai Guangdong519070, China)

Abstract: Lates calcarifer, known as blind mullet, is widely distributed from Ryukyu to the Indian Ocean. Because of its fast growth rate, no intermuscular spines, delicious taste, and high nutritional value, it is loved by farmers and consumers. It is one of the essential breeding fish species in the southern region of China. L. calcarifer belongs to fish of relatively strong vitality. It can adapt to water from freshwater to a salinity of 56 ‰, belonging to euryhaline fish. At present, it can be cultured in both seawater and freshwater. L. calcarifer commands a high price in the market for its delicious meat. It can be fed with artificial feed or lowcost fish. In 2021, the total production of Lates calcarifer in Guangdong Province was less than 50 000 t, accounting for more than 80% of the country’s total production, and the total production of it in Zhuhai accounted for more than 40 % of the country, where it has formed a more complete production, processing and sales industry chain.

Glycerol monolaurate (GML), also known as monolaurate glycerol, is a mediumchain fatty acid ester extracted from natural plants. It is a compound formed by lauric acid and glycerol, which can emulsify, preserve, and inhibit bacterial growth in the digestive tract. It is a food emulsifier with emulsifying and preservative functions and is widely used in food and cosmetic industries. The shape is generally oily or finely granular crystals, white or pale yellow. Studies have shown that mediumchain fatty acid monoglycerides (MCFA) with their short carbon chains are rapidly absorbed and undergo rapid oxidative metabolism in the animal to provide the body with energy more quickly. The mechanism is that GML as a mediumchain fatty acid ester can easily cross the intestinal mucosa and enter the blood and liver. Studies have shown that MCFA can not only assist in the treatment of lipid absorption disorders and malabsorption syndromes but also have a beneficial effect on gastroenteritis and diabetes. It is believed that GML could affect the body’s lipid metabolism by promoting the oxidation of fatty acids in the liver and reducing body fat by consuming adipose tissue. Unlike longchain fatty acids, mediumchain fatty acids such as lauric acid can significantly reduce body weight and body fat content in mice. In addition, GML can improve the absorption of nutrients in farmed fish, accelerate growth, increase feed conversion rate, and improve body damage. Highdensity fishing and massive use of highfat, highenergy feed make the water eutrophication serious, and farmed fish generally have excessive fat accumulation and fish body odor problems, affecting their health, meat taste, and nutritional value.

In this study, the effects of glycerol monolaurate on growth performance, serum immune parameters, metabolismrelated enzyme activities, and intestinal digestive enzyme activities were analyzed by feeding different doses (0 g·kg-1, 1 g·kg-1, 2 g·kg-1, 4 g·kg-1) to artificially farmed L. calcarifer to improve commercial value, achieve quality and efficiency improvement and promote the healthy and sustainable development of the industry. We fed 200 L. calcarifer with body weight (442.727±54.423) g, body length(28.438±1.493) cm by basal diet with GML at 0 g·kg-1 (G0 group, as the control group), 1 g·kg-1 (G1 group), 2 g·kg-1 (G2 group) and 4 g·kg-1 (G4 group) for eight weeks. Results showed that the addition of different levels of GML to the feed significantly reduced the ratio of viscerosomatic index (VSI), hepatosomatic index (HIS), and intraperitoneal fat ratio (IPF) in the fish compared to the control group. The ratio of VSI, HSI, and IPF was the ratio of wet weight of the organism’s organs to the unit body mass, and the change of its value reflected the change of fat content in body. The reduction in its value was therefore beneficial for reducing the accumulation of fat in the fish and improving health. Histomorphological analysis of liver showed a significant reduction in vacuolisation in GML group compared to the control group. The analysis of liver lipid metabolizing enzyme activities and changes in serum liver function related indicators also indicated that GML feeding could improve liver function. In this study, the activity of liver lipid metabolizing enzymes including hepaticlipase (HL), lipoprteinlipase (LPL) and HL+LPL were significantly higher in the test group than those in the control group, while serum triglyceride (TG), total cholesterol (TC), and lowdensity lipoprotein cholesterol (LDLC) were lower than those in the control group. So, GML could significantly improve lipid deposition in the body and alleviate liver damage, but the specific regulatory mechanism was still not completely clear and needed further research and analysis. The activity of glutamicpyruvic transaminase (ALT) within the serum of the test group was significantly higher than that of the control group, while globulin (GLB) content changed in the opposite direction, aspartate aminotransferase (AST) activity was not significantly different between the groups. In addition, results of liver antioxidant capacity showed that after 8 weeks of feeding GML, the activities of total antioxidant capacity (TAOC), superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) content in the livers of G2 group were significantly higher and malondialdehyde (MDA) concentration was significantly lower compared to the control group. It indicated that GML could effectively relieve the stress state of fish, reduce liver tissue damage and improve the antiinflammatory ability of L. calcarifer. The diet supplemented with 2 g·kg-1 of GML significantly increased the activity of amylase (AMS), lipase (LPS), and protease (PRS) in the intestine of L. calcarifer, indicating that GML can penetrate deep into the gastrointestinal interior under the protection of ester bonds, making it effective in promoting the digestive function of fish intestine. Conclusively, the findings suggested that GML supplementation contributed to improving lipid metabolism, digestive ability, immunity, liver tissue morphology, physiological function, and regulating the health of Lates calcarifer body, and the optimal GML supplementation level was 2 g·kg-1.

Keywords: glycerol monolaurate; Lates calcarifer; lipid metabolism; liver function

Related Articles | Metrics

Evaluation on culture performance of the first generation of odd year “Changdang Lake 1” Eriocheir sinensis during the adult culture stage

2022, 44(6): 747.

Abstract ( 99 )

PDF (2252KB) ( 388 )

Evaluation on culture performance of the first generation

of odd year “Changdang Lake 1” Eriocheir sinensis

during the adult culture stage

ZHUANG Zhenjun1,2,3，ZHANG Dongdong1,2,3， JIANG Xiaodong1,2,3，CHEN Wenbin4，
CHEN Xiaowu1,2,3， CHENG Yongxu1,2,3，WU Xugan1,2,3
（1. Key Laboratory of Freshwater Germplasm Resources, Ministry of Agriculture and Rural Affairs，Shanghai Ocean
University, Shanghai201306, China; 2. Shanghai Collaborative Innovation Center for Cultivating Elite Breeds and
Greenculture of Aquaculture Animals, Shanghai201306, China; 3. National Demonstration Centre for Experimental
Fisheries Science Education， Shanghai Ocean University，Shanghai201306, China; 4. Changzhou
Jintan District Fisheries Technical Extension Station, Changzhou Jiangsu213200, China）

Abstract: High survival rate and large size are the main breeding standards for strain A and strain B of “Changdang Lake 1” Chinese mitten crab (Eriocheir sinensis). In order to explore the culture performance of the first generation of “Changdang Lake 1” Eriocheir sinensis in odd year population, juveniles were reared to adult in 9 similar ponds close to production conditions in Changdang Lake area from March to November 2020. The average body weight, weight growth rate, specific growth rate, genital molting rate, gonadal development, survival rate, yield, feed coefficient ratio and final body mass distribution were evaluated among strain A, strain B and the control group (unselected population). The results showed as follows: 1) The average body weight of strain B was significantly higher than that of other groups from June to October (P<0.05), and the average body weight of strain A was slightly higher than that of the control group, but there was no significant difference (P＞0.05); moreover, a clear difference began to emerge in the average body weight of male and female in June; 2) At early stages of culture (AprilJune), the weight growth rate (WGR) of three groups was more than 200%, and the WGR of strain B was significantly higher than that of strain A and the control group (P<0.05); from August to October, the weight growth rates of male were less than 60%, and that of female were generally less than 30%; 3) The changes of specific growth rates were similar to weight growth rates of the three groups; after August, the daily increase rate of body weight of male was less than 0.8%, and that of female was less than 0.5%; 4) There was no significant difference in genital molting rate among three groups (P<0.05); the genital molting rate of male and female crabs increased gradually from July, and the genital molting rate of female was about 20% higher than that of male in the same period from August to September; by September 20th, the genital molting rates among three groups were nearly 100%; 5) The gonadosomatic index gradually increased from September to November among all groups, but there was no significant difference (P<0.05); from October to November, the gonadosomatic index of female in three groups was higher than that of male; 6) The hepatosomatic index of female decreased from September to November in the three groups, while the change of hepatosomatic index of male was different among three groups; the hepatosomatic index of male in two selected strains slightly increased at the beginning, and then decreased from September to November, while the hepatosomatic index of the control group decreased month by month, but there was no significant difference among all groups (P＞0.05); 7) In terms of male crabs, the distribution proportion of large size (≥250g) in strain B was significantly higher than that in strain A and the control group (P<0.05), while the proportion of small size (< 125 g) in strain A was significantly higher than that in the other two groups (P<0.05); in terms of female crabs, the distribution proportion of large size (≥150 g) in strain B was significantly higher than that in the other two groups (P＞0.05). Although the distribution proportion between 125200 g in strain A was higher than that in the control group, there was no significant difference (P＞0.05); 8) In terms of survival rate, the total survival rates of two selected strains were significantly higher than that of the control group (P<0.05), and the total survival rate of strain A was significantly higher than that of strain B (P<0.05), among which the female survival rate of strain A was as high as 76.93%; 9) The yield of the two selected strains were significantly higher than that of control group (P<0.05), and there was no significant difference between strain A and strain B (P＞0.05); 10) In terms of feed conversion rate, strain B was the lowest and the control group was the highest, but there was no significant difference among three groups (P＞0.05). In conclusion, the survival rate of “Changdang Lake 1” strain A was significantly higher than that of the other two groups, the average body mass of “Changdang Lake 1” strain B was higher than that of the other two groups, and the yield and feed conversion rate of two selected strains were higher than those of the unselected population. The results provide a detailed practical reference for the breeding of new Eriocheir sinensis strains, and provide data for the continuous breeding and promotion of “Changdang Lake 1” Eriocheir sinensis.

Keywords: Eriocheir sinensis; Changdang Lake 1; complete set line breeding; culture performance; gonadal development

Related Articles | Metrics

Influence of temperature and substrates on burrowing behavior of Scapharca kagoshimensis with different body sizes#br#

2022, 44(6): 759.

Abstract ( 88 )

PDF (2039KB) ( 393 )

Influence of temperature and substrates on burrowing

behavior of Scapharca kagoshimensis with different body sizes

ZHANG Yang1,2, JIANG Yazhou1, LING Jianzhong1, SUN Peng1,
WANG Jie1,2, JIANG Tianqi1,2, TANG Baojun1
(1.East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai200090,
China; 2. College of Fisheries and Life Science, Shanghai Ocean University, Shanghai201306, China)

Abstract: Behavioral plasticity plays an important role in the adaptation of animals to environmental changes. The tidal flat substrate is the place for burrowing shellfish to forage, inhabit and avoid predators. The tidal flat substrate environment directly affects the species distribution, composition, growth and reproduction of shellfish, as well as their burrowing behavior. The ark shell Scapharca kagoshimensis is an important economic clam. In recent years, due to overfishing and environmental changes, the natural resources of Scapharca kagoshimensis have greatly declined. In order to restore the declining natural resources, stock enhancement of S. kagoshimensis has been carried out in many regions in China. Scapharca kagoshimensis is a typical burrowing shellfish. The time and depth of sand burrowing affect its ability to feed, survive and avoid predators. These parameters are important indicators for assessing the health of Scapharca kagoshimensis and selecting a suitable area for bottom farming. Therefore, it is of great significance to study the burrowing behavior of S. kagoshimensis for its stock enhancement and farming. This study can provide basic data for future study on the environmental adaptation and habitat selection of S. kagoshimensis, and provide guidance for the selection of bottom farming areas of S. kagoshimensis. We collected S. kagoshimensis in Xiangshan Bay, Zhejiang Province, China, and investigated the effects of water temperature and substrate particle size on the burrowing behavior of S. kagoshimensis with different body sizes in a nearby laboratory. Two body sizes were set in the experiment: the average shell length (21.15 ± 1.64) mm and (9.78 ± 2.79) mm, which corresponded to the sizes of firstyearold seedlings and secondyearold spat, respectively. According to the average seawater temperature in different seasons in Xiangshan Bay, 4 temperature gradients were set: 12 ℃, 20 ℃, 25 ℃, 32 ℃. According to the bottom sediment composition, four kinds of sediment particle sizes were set: coarse sand (>1 700 μm), medium sand (8301 700 μm), fine sand (380830 μm), and sea mud. The experiment was carried out in plexiglass experimental devices with a length of 25 cm, a width of 4 cm, and a height of 15 cm. A digital camera with a resolution of 2 160×1 080 pixels was placed in parallel above the plexiglass experimental device to observe and record the burrowing process and behavior. The first inmud time, the maximum burrowing depth and the burrowing rate of the clams were measured and calculated respectively. The first inmud time: the time when the first S. kagoshimensis began to burrow into the sand, and the judgement criterion was that more than half of the shells burrowed into the sand. Burrowing rate = (1-Et/20)×100%, where Et was the number of clams in the experimental device who did not burrow into the sand in time, and 20 was the total number of clams. The sand burrowing process of S. kagoshimensis was intermittent, and the burrowing depth in the sand was limited to submerge of most of the shell. The first inmud time of smallsize S.kagoshimensis was significantly lower than those of largesize ones (P<0.05), indicating that smallsize S.kagoshimensis adapted to the environment faster, probably because the shell of smallsize S.kagoshimensis was thinner. In order to avoid predators, it was necessary to burrow into the substrate as soon as possible. The burrowing rate of smallsize S.kagoshimensis was significantly higher than that of largesize ones with different particle sizes and time(P<0.05). Considering the first inmud time and the burrowing rate, the sand burrowing capability of smallsize S.kagoshimensis was stronger than that of largesize S.kagoshimensis. The burrowing depth in the fine sand, medium sand and coarse sand of largesize S.kagoshimensis was significantly higher than that of smallsize ones (P<0.05). This might be due to the difference in locomotion and sand burrowing abilities of different sizes. Largesize S.kagoshimensis had larger foot, which generated greater friction with the substrate, allowing them to burrow deeper. When the temperature was lowered to 12 ℃, the first inmud time of two sizes of S.kagoshimensis was both prolonged, indicating that the low temperature had an inhibitory effect on the burrowing speed of S.kagoshimensis. The maximum burrowing depths of S.kagoshimensis at 12 ℃ and 32 ℃ were significantly lower than those at 20 ℃ and 25 ℃ (P<0.05), indicating that too low or too high temperature would both influence the sand burrowing ability. Under low temperature conditions, as a survival strategy, S.kagoshimensis might reduce the burrowing speed to cope with the energy loss, thereby improving their survival rate. Sea mud had the most significant effect on the burrowing behavior of S.kagoshimensis. The two body sizes of clams had the longest burrowing time in sea mud, and the burrowing depth in sea mud was also very small. The first inmud time of smallsize S.kagoshimensis in fine sand was the shortest, while the largesize clams were most likely to burrow in coarse sand, indicating that the particle size of the substrate had a significant effect on the behavior of S. kagoshimensis, and sandy substrates with large particle size were more suitable for the survival of S.kagoshimensis. The burrowing rate increased with the sand particle size. This might be due to the fact that the algae attached to the sand substrate were more than that in the mud substrate, which was more suitable for the feeding activities of shellfish. At the same time, the sand substrate had a larger gap between particles than the mud sediment and was easy to disperse, so the resistance to shellfish in the process of burrowing was relatively small. The present study showed that water temperature, substrate particle size and body size all have significant effects on the burrowing behavior of S. kagoshimensis. The smallsize S.kagoshimensis had shorter first inmud time, higher burrowing rate, and stronger burrowing capacity than the largesize ones. In the sandy substrate, S.kagoshimensis had shorter first inmud time, higher burrowing rate and burrowing depth than those in sea mud. The burrowing performance of S.kagoshimensis at 20 ℃ and 32 ℃ was better than that at 12 ℃ and 32 ℃. It is suggested to choose sandy substrates with larger particle size in spring and autumn for bottom farming and stock enhancement of S. kagoshimensis.

Keywords: Scapharca kagoshimensis; water temperature; substrate particle size; body sizes; burrowing behavior

Related Articles | Metrics

Preparation and characterization of single-chain antibodies against Pseudomonas plecoglossicida haemolysin co-regulatory protein

2022, 44(6): 769.

Abstract ( 80 )

PDF (2155KB) ( 389 )

Preparation and characterization of single-chain antibodies against

Pseudomonas plecoglossicida haemolysin

co-regulatory protein

CHEN Yun1, SHI Hui2, XU Wenjun2, WANG wei2, XIE Jianjun2
(1.Marine and Fishery Institute of Zhejiang Ocean University, Zhoushan Zhejiang316022, China;
2.Key Laboratary of Marine Culture and Enhancement of Zhejiang Province, Marine Fisheries
Research Institute of Zhejiang Province, Zhoushan Zhejiang316021, China)

Abstract: Visceral granulomas disease (VGD) is a bacterial disease caused by Pseudomonas plecoglossicida. It can infect a variety of aquaculture economic fishes including large yellow croaker (Larimichthys crocea), which seriously hinders the healthy and sustainable development of L. crocea aquaculture. Therefore, it is urgent to prepare a specific antibody that can quickly identify P. plecoglossicida and can be used for research and development of rapid clinical diagnosis of VGD in L. crocea in the future.

In this study, we used P. plecoglossicida recombinant haemolysin coregulatory protein (Hcp) as the antigen to screen the specific singlechain antibody (HcpscFv) from the rabbit natural phage scFv library using solid phase antigen screening method. After four rounds of screening and enrichment, the recovery of the fourth round was about 42 times that of the first round, indicating that the target antibody was effectively enriched. 96 phagepositive monoclones and 96 phagenegative monoclones were selected from the plate of the fourth round of elute titer determination, we coated Hcp recombinant protein on a 96well plate, and used phageELISA to detect the specificity of phage monoclones. After detecting the absorbance of phage monoclones by microplate reader and comparing the absorbance, the positive clones meeting the requirements were screened out. The obtained positive clones were amplified and the phagocytic particles for sequencing were extracted. According to the results of the obtained sequences analysis, the repeated sequences were deleted and 16 positive clones were screened out. PhageELISA assay was carried out again on 16 positive clones. We detectd and compared the absorbance of 16 positive clones. Finally 7 clones with higher specificity were selected, named A5, F11, D2, D10, G5, G8, and H12.

According to the sequences of these seven clones, we used the Primer software to design specific primers and select appropriate restriction enzymes. Bam HⅠ and Hind Ⅲ restriction sites were added to the upstream and downstream primers of A5 and F11, and Nco Ⅰ and Not Ⅰ restriction sites were added to the upstream and downstream primers of G5, G8, D2, D10 and H12, respectively. The extracted macrophages were used as templates for PCR amplification. Then we carried out agarose gel electrophoresis experiment and recovered the target fragment. The recovered product was ligated with pEASYT vector, and the ligated product was transferred into Trans1T1 for culturing. The next day, a single colony was selected and cultured to extract plasmid pEASYTHcpScFv. We used the restriction enzymes BamH I+Hind III and Nco I+Not I to carry out double digestion on pEASYTHcpScFv and pET30a (+) respectively. The digested products were subjected to agarose gel electrophoresis, and the target fragment was recovered. And the recovered products, namely, the target fragments of pEASYTHcpScFv and expression vector pET30a (+) were ligated to construct recombinant plasmid pET30aHcpScFv.

The recombinant plasmid pET30aHcpScFv was transformed into competent Escherichia coli BL21(DE3) pLysS for small quantity induction and expression. The recombinant plasmid was induced at 30℃ for 5 h at a final concentration of 0.4 mmol·L-1 IPTG and then detected by SDSPAGE experiment. A5, F11, G5, G8, D2 and D10 all had a specific protein band at about 33 kDa. The result showed that they could be stably expressed in Escherichia coli BL21(DE3) pLysS, while H12 could not be expressed stably.

A5, F11, G5, G8, D2, D10 were induced and expressed in large quantities. We centrifuged the bacteria to collect the bacterial precipitation and lysed it with loading buffer. After ultrasonication and centrifugation, supernatant and precipitate were collected. We lysed the precipitate with buffer B and centrifugated the liquid to obtain precipitation lysate. The target protein in supernatant and precipitation lysate was detected by SDSPAGE experiment respectively for protein solubility analysis. The results showed that F11, G8, D2 and D10 had target bands in precipitate lysates, indicating that these four strains existed as inclusion bodies. A5 and G5 had bands both in supernatant and precipitation lysate, but the protein content of precipitation lysate was significantly higher than that of supernatant, indicating that two strains mainly existed as inclusion bodies.

A5, F11, G5, G8, D2, D10 were induced and expressed in large quantities. We centrifuged the bacteria to collect the bacterial precipitation and lysed it with NiDenatureurea buffer. After ultrasonication and centrifugation, we collected supernatant, namely precipitation lysate, and the target protein bands were successfully observed by SDSPAGE experiment. The protein solution was purified by NiIDA6FF prepacked gravity column, and relatively clear target protein bands were observed at the expected position by SDSPAGE experiment. Western Blot experiment was carried out to further check whether the target protein structure was intact after purification, using mouse primary antibody corresponding to Histag on the target protein and goat antimouse secondary antibody. The results showed that obvious brown bands could be observed on the PVDF membrane at the position of 35 kDa, which was consistent with the position of the bands in the SDSPAGE experiment, indicating that the target protein had a specific reaction with Histag mouse monoclonal antibody. The result proved that the recombinant protein was structurally intact after purification, which also indicated that pET30aHcpScFv against P. plecoglossicida recombinant Hcp could be effectively expressed in Escherichia coli BL21(DE3) pLysS.
The result of this study provided a simple and rapid method for the rapid preparation of a large number of specific antibodies against P. plecoglossicida recombinant Hcp. We used the solid phase antigen screening method and the principle of specific binding of antigens and antibodies to screen the specific scFv from the rabbit natural phage scFv library. Then the specific scFv was ligated with pET30a(+) to construct a recombinant plasmid. In order to obtain the recombinant protein, we transferred the recombinant plasmid into E.coil BL21(DE3) pLySs for induction and expression. Finally, the target antibody was obtained by purifying the recombinant protein. The result provides a scientific basis for the clinical rapid diagnosis technology of VGD in L. crocea in the future.
Keywords: Larimichthys crocea; whitespots disease; Pseudomonas plecoglossicida; scFv

Related Articles | Metrics

Spatiotemporal distribution of fishing grounds in the Bohai Sea and its adjacent waters based on AIS

2022, 44(6): 780.

Abstract ( 113 )

PDF (4754KB) ( 421 )

Spatiotemporal distribution of fishing grounds in

the Bohai Sea and its adjacent waters based on AIS

CHEN Renli1,2, WU Xiaoqing1,3, LIU Baijing1,2, WANG Yueqi1,3
(1. Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai Shandong264003, China;
2. University of Chinese Academy of Sciences, Beijing100049, China; 3. Key Laboratory of Coastal Environmental
Processes and Ecological Remediation, Chinese Academy of Sciences, Yantai Shandong264003, China)

Abstract: Automatic identification system (AIS) is a new type of navigation aid system applied to shiptoship and shiptoshore. It can monitor vessel activity in real time and plays an increasingly important role in vessel collision avoidance, vessel monitoring, and maritime management. In the past ten years, the popularization and application of AIS transmitters has made AISbased dynamic trajectory data valuable for scientific research in marine traffic management, marine fisheries management, and marine spatial planning management. With its high spatial and temporal resolution, AIS data provides a good source to reveal the characteristics of maritime traffic activities and fishing intensity. Since the introduction of AIS, significant progress has been made regarding the use of AIS data for identifying fishing behavior, quantifying fishing intensity, and assessing marine ecological stress. However, previous studies lack a description of the overall spatial and temporal distribution pattern of fishing activities in coastal sea areas, which affects the efficiency of marine fishing activity management and marine ecological protection in regional waters. The Bohai Sea and its adjacent waters is one of the important distribution areas of fishing grounds in China, with abundant fishing resources, extensive distribution of fishing ports and fishing vessels, and intensive fishing activities. Nevertheless, in recent decades, due to the impact of overfishing and landsource pollution, fishery resources have been seriously degraded. It is an urgent need to understand the distribution and level of overall fishing activity in regional waters, so as to provide decisionmaking support for marine fishing activities, marine ecological environment protection, and the restoration of marine fisheries resources. Based on AIS data from marine vessels in the Bohai Sea and its adjacent waters in 2014 and 2018, this study mapped the range of the fishing ground, and analyzed the temporal and spatial distribution characteristics of fishing grounds and their influence factors. First, the speed threshold under fishing states was determined based on the speed frequency density distribution of fishing vessels and a Gaussian mixed model. Secondly, the kernel density estimation and hot spot analysis were combined to map fishing grounds. The standard deviation ellipse method was used to calculate the spatial distribution center of fishing grounds. Then the distribution of fishing grounds for the months and quarters of 2018 and the same MMSI information for 2014 and 2018 were mapped. Finally, based on the statistical analysis and the aggregation index, the quantitative structure and spatial distribution characteristics of fishing grounds were analyzed, and the factors that caused the differences in the spatial and temporal patterns of fishing grounds were discussed. The results showed that there were significant monthly and quarterly differences in the spatial distribution of fishing grounds in the Bohai Sea and its adjacent waters. It was mainly distributed in Yanwei nearshore area and sea area near the Bohai Strait. Except for the summer fishing moratorium period from May to August, the average percentage of the sea area near the Bohai Strait and Yanwei nearshore fishing grounds in the total area of all fishing grounds each month was about 52.10%. While the scale of fishing activity in the Bohai Sea was small, it was scattered only in the coastal waters of Qinhuangdao, northern areas of Huanghua, and Laizhou Bay. The largescale fishing activities were mainly concentrated from September to December after the summer fishing moratorium, with widespread fishing grounds and marked changes in spatial morphology. Among them, the fishing grounds in September were the largest, with an area of about 15 355.29 km2. In October, fishing grounds had the highest level of clustering, and the aggregation degree index reached 37.49. Autumn was the most active season for fishing activities in the sea area, and the gathering area accounted for about 16.48% of the total study area, showing the characteristics of contiguous distribution in the sea area near the Bohai Strait. The spatial distribution center of fishing activity in summer was the most to the west, and the spatial distribution centers of fishing grounds from shifted eastward with the changes of spring, autumn and winter. Based on the AIS information statistics of the same MMSI fishing vessels, it was found that compared with 2014, the distribution of fishing grounds in 2018 changed slightly, but the spatial range of fishing grounds in 2018 was expanded and the spatial distribution was more concentrated, with the area of fishing grounds approximately 1.8 times that in 2014. Fishing grounds in the coastal waters of the Bohai Sea increased significantly. The center of spatial distribution shifted to the west. The spatial and temporal variation of fishing grounds was comprehensively affected by some factors, such as seasonal change, ecological habits of fishery organisms, the summer fishing moratorium, space regulation of fishing zones, and stock enhancement. For example, affected by the monsoon climate of medium atitudes and the Spring Festival, the distribution of fishing grounds was relatively small from January to February. As an important migratory channel for fishery organisms in the Bohai Sea and its adjacent waters, the migration fish in the sea area near the Bohai Strait and Yanwei nearshore showed obvious gathering from October to November, making largescale fishing activities in these two months possible. The summer fishing moratorium obviously limited the monthly and seasonal distribution characteristics of fishing activity, which was one of the effective measures to control the fishing activities. From the regional scale and overall perspective, the study quantitatively revealed the spatial and temporal variability characteristics of fishing activities in the Bohai Sea and its adjacent waters based on AIS data. The results can provide decisionmaking support for the regulation of fishing activities, the sustainable development of marine fishing industry, the restoration of fishery resources, and marine spatial planning management in the Bohai Sea and its adjacent waters. This study also further confirms that AIS big data has good application value in marine fishery scientific research, which can realize rapid identification and monitoring of fishing intensity and its distribution pattern in regional waters, and further expand the application research field of AIS data.

Keywords: fishing activity; fishing behavior; fishing vessel; AIS; Bohai Sea

Related Articles | Metrics

Spatial and temporal distribution characteristics of sail-style stow net fisheries in Jiangsu Province

2022, 44(6): 790.

Abstract ( 107 )

PDF (4843KB) ( 422 )

Spatial and temporal distribution characteristics of sail-style

stow net fisheries in Jiangsu Province

LIU Yong, CHENG Jiahua, ZHANG Hanye
(Key Laboratory of East China Sea Fishery Resources Exploitation and Utilization, Ministry of Agriculture and Rural
Affairs; East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai200090, China)

Abstract: In the early 1980s, the technical personnel of Qidong, Jiangsu Province, made improvement on the basis of Korean anglerfish nets and successfully developed sailstyle stow nets. Because of the large size of the main scale of stow net, the flexibility of fishing operation, high yield, low cost and good efficiency, it was quickly promoted. By the end of 1980s, Jiangsu developed 200300 sailstyle stow net fishing vessels, and in the early 1990s, it was introduced to Zhejiang, and by the end of the 20th century, the number of fishing vessels in the whole East China Sea area had grown to nearly 3 000. However, the small mesh and poor selectivity of the gear have caused serious damage to juvenile fish resources, which caused widespread concern among fisheries management and the public. In 1995, the Fishery Bureau of East China Sea Region formulated the "Implementation Measures for the Management of Sailstyle Stow Net Operation", which controlled the total number of fishing vessels, restricted the operation area and the number of nets, and implemented fishing moratorium, and the total number of fishing vessels should not exceed 1 000; in 2 000, the State Administration of Fishery and Port Supervision issued the “Interim Measures for the Management of Sailstyle Stow Net Operations”, which implemented the management principle of special permit, year by year reduction and final elimination of sailstyle stow net operations. After more than 10 years of control, although sailstyle stow nets have not withdrawn from the fishing industry, the number of fishing vessels has been effectively controlled and reduced, and the total number of fishing vessels in Jiangsu is now controlled in hundreds. Since the overall fisheries related to sailstyle stow net fishing vessels are less studied, this paper analyzes the daily production and catch structure and spatial and temporal distribution of fishing grounds based on a large number of random sampling survey data of sailstyle stow net fishing vessels along Jiangsu coast in 2014, to lay foundation for further research related to fishing grounds zoning and other related studies in the future, and also provide technical support for the formulation and implementation of related fisheries management measures. The results of this study show that the production waters of sailstyle stow net fishing vessels in Jiangsu Province are relatively concentrated in Dasha fishing ground, and the fishing grounds expand to the south, offshore or nearshore waters in individual months according to the changes of fishery resources. The water depth range is 3050m in relatively concentrated waters of fishing vessel distribution, and the proportion is more than 50%. The sailstyle stow net fishing area is located in the intersection of the Yellow Sea and the East China Sea, and belongs to the area where the “Yellow Sea cold water mass” and Kuroshio tributaries meet, and the water masses of different natures often mix, with frequent exchange between the upper and lower water layers, rich in nutrient salts and high primary productivity. The water depth gradient in the production waters of Jiangsu Province is relatively small, and the bottom is relatively flat; the substrate is the mud and sand of the radiating sandbar, which is suitable for anchoring and releasing the net by sailstyle stow net. The span of the fishing range in the eastwest direction and the northsouth direction shows a relationship between this and the other, that is, the distribution of fishing vessels expands in the eastwest direction (longitude range), then shortens in the northsouth direction (latitude range); and vice versa. This relationship may be due to a change in the distribution of fishing resources, which leads to a change in the operating waters of fishing vessels. The number of fishing areas covered by each month of operation is related to the production of fishing vessels, i.e., there is a significant negative correlation between the number of fishing areas and average CPUE. Stated differently, the higher the production, the more concentrated the fishing area is conversely, the higher the number of fishing areas covered by the operational area, the lower the average production. This relationship responds to the production strategy of fishermen, i.e., when yields are not high, fishing vessels spread out and try to expand their range to find new fishing grounds; once they find fish, they gather. There is a relatively stable central water area (Dasha fishery) for sailstyle stow net production; with the emergence of the main economic species in season, it will directly affect the changes in the distribution of operating waters. The composition of the catch changes somewhat with the season, and the spatial and temporal variation of resources of the main economic species is the main reason for the variation of sailstyle stow net fishery. In winter and spring, small pelagic fish, small shrimps and juvenile economic fish are the main targets of sailstyle stow nets; in autumn, economic fish species such as hairtail (Trichiurus haumela), small yellow croaker (Pseudosciaena Polyactis) and swimming crab (Portunus trituberculatus) are the main fishing targets. In comparison with historical literature, it is found that the main catch species of sailstyle stow nets are replaced by crustacean crabs with relatively lower nutritional class instead of common silvery pomfret, which shows that the composition of sailstyle stow nets has changed, reflecting a certain degree of change in the structure and function of the marine ecosystem. Although measures have been taken to eliminate sailstyle stow net fishery, because of the irreplaceable advantages of low cost and high efficiency, hundreds of fishing vessels are still in production in Jiangsu Province. In the present situation that sailstyle stow net operation can not be completely banned, consideration should be given to further strengthen the strict management of the mesh size of sac nets, strictly control the number of nets carried by fishing vessels, and minimize their fishing intensity, so as to effectively protect the growth and replenishment of juvenile economic fish and maintain the sustainable development of fisheries.

Keywords: sailstyle stow net; sampling survey; average daily production; catch composition; fishery distribution

Related Articles | Metrics

Morphometric correlation and regression of morphometrical traits and total weight of 24-month-old Apostichopus japonicus(purple sea cucumber)

2022, 44(6): 802.

Abstract ( 68 )

PDF (1222KB) ( 383 )

Morphometric correlation and regression of morphometrical

traits and total weight of 24-month-old

Apostichopus japonicus(purple sea cucumber)

HAN Sha1, ZHAO Bin1, LI Chenglin1, WU Peng2, HU Wei1, XIN Yu3, WANG Qi1, YAO Linlin1
(1. Marine Science Institute of Shandong Province, Qingdao Shandong266104, China； 2. Fishery Technology
Extension Station of Wendeng District Weihai City, Weihai Shandong264400, China; 3. Shandong Foreign
Economic Trade and Aquatic Product Co., Ltd, Jinan250014, China)

Abstract: Sea cucumber Apostichopus japonicus is one of the most commercially important mariculture species in China. In recent years, the market requirement and consumption of sea cucumbers have gradually increased. Therefore, the sea cucumber farming industry has been developping rapidly and become the pillar industry of coastal fishery economic in China, especially in the north China. Although the development of sea cucumber industry is rapid, several issues are demanding prompt solutions, such as lack of basic biology research, germplasm degradation, slow growth and reduced stress resistance of the existing varieties. Compared with other aquaculture species, special varieties with highquality economic characteristics are few, and the lack of improved varieties in sea cucumber restricts the development of farming industry. Therefore, germplasm creation has become one of the key points of sea cucumber farming research.

At present, new varieties of sea cucumber have been selected and bred successively with excellent economic characteristics, such as fast growth rate, high temperature resistance and disease resistance after great effort of breeding research institutes and production units for many years. It has laid the germplasm foundation for the further development of the sea cucumber industry in China. A. japonicus（purple sea cucumber） is a kind with special skin characteristic of sea cucumber. These highquality strains will lay the foundation for the diversification of sea cucumber species.

Accurate size measurements are important for the determination of growth performance for aquaculture. Most methods are used to estimate growth through length frequency data analysis, which depends on body measurements and biometric relationship. It is very difficult to measure the growth characteristics of sea cucumbers because of the difficulty in determining age by stress and dirty discharge, water spitting after leaving water, and body stretching and deformation. Precise measurements of body weight and body length in sea cucumber are challenging under different conditions. The body length of sea cucumbers can change considerably by elongation or contraction, and the body weight also varies considerably depending on the amount of water in respiratory trees and the intestinal content. Body size and body weight relationship is also important in determining the nutritional condition of the organisms. At the moment, there are no standard evaluation methods for accurate measurement of sea cucumber. In addition, compound indices that combine different biometric parameters can be applied to generate more precise biometric relationships.

The study was conducted to explore morphometric correlation of morphometrical traits and body weight of 24monthold A. japonicus（purple sea cucumber）. 300 individuals were selected and relaxed by placement in containers with menthol of 0.2 mol·L-1 for 5 to 10 min. Then boby length(L), body width(W) and total weight(TW) were measured for each individual. When the body was relaxed and stretched, the camera was used to take pictures of the samples, and the data of body length and width were obtained by image calculation with camera measure software. Body length was measured from the center of the tentacle crown to the anus(curved length). Body width was measured dorsally at the widest point. Total weight was measured with a digital balance, accurate to 0.01 g. Indirect methods were used to estimate the growth by use of compound index. A compound index that combined body length and body width to produce SLW index(L×W) and its transformation Le were utilized to obtain more precise biometric relationships. Lengthweight relationship was evaluated and the optimal fitting morphometrical traits and curve model were also selected by regression analysis.

Results showed that the coefficients of variability of growth characters were 31.52%66.85% and the highest and lowest character was body weight and SLW, respectively. The regression analysis results of the best fitting model of morphometrical traits and body weight were all power function model and Le was the best fitting morphological parameter for lengthweight relationship. Biometric relationship was useful to carry out transformations of body length to total weight. Body length and weight relationship have not been established for all sea cucumber species. First study applying a compound index on A. japonicus（purple sea cucumber） was accomplished. Body length, as well as body width, was also an important morphometrical trait. Therefore, it could be assumed that recalculated length from SLW might be useful to get accurate body length of sea cucumber. This study established indirect method for estimation of total weight in A. japonicus（purple sea cucumber）. Using estimated body length(Le) from the compound index SLW enhanced weight estimation accuracy in this study. The SLW compound index could reduce the variability of body length to homogenize the samples, facilitating the calculation of growth parameters by indirect method.

A power model was used in the weight regression of A. japonicus（purple sea cucumber）, and a strong correlation was found between weight and SLW. The 24monthold A. japonicus（purple sea cucumber） grew allometrically with negative allometry tendency. It grew rapidly with better performance of morphological traits than body weight. The relationship among morphological traits at different development stages was unclear, neither the impacts of morphological variation on economically important traits at different stages. This study developed an algorithm to estimate A. japonicus（purple sea cucumber） weight by measuring its feature, including body length and body width. The indirect method and Leweight regression models in this study may be useful in growth evaluation of A. japonicus（purple sea cucumber）. The results of this paper provide theoretical guidance for growth and cultivation for A. japonicus（purple sea cucumber）.　

Keywords: Apostichopus japonicus（purple sea cucumber）; sizeweight relationship; morphometrical traits; total weight

Related Articles | Metrics

Archive