Transport and distribution of nutrients in anchovy spawning ground to the southern waters of Shandong Peninsula

The distribution of nutrients and the effect of side transport of nutrients on anchovy spawning ground to the southern waters of Shandong Peninsula are discussed based on the data collected in June 2000, May and June 2001. The coastal current and upwelling are the main physical processes of nutrient transport to the southern waters of Shandong Peninsula. The concentrations of nutrients, Chl-a, the density of anchovy eggs, larva and juvenile fish increase obviously where they are greatly affected by these processes, while the contents of nutrients and Chl-a, the density of anchovy eggs, larva and juvenile fish decrease significantly where these processes diminish or disappear. The investigation suggest that the side transport of nutrients by Lubei (North Shandong) coastal current in the northern area causes the Chl-a content to be high and dense anchovy eggs, larva and juvenile fish to be dense in the coastal area of the Chengshan Cape. In the southern area, the riverine input from Subei irrigation ditch with high content of nutrients inshore and upwelling in the western edge of the Huanghai Sea Cold Water offshore should be responsible for high Chl-a concentration and dense anchovy eggs, larva and juvenile fish. It is possible that these processes of nutrient transport have controlled the anchovy spawning ground to the southern waters of Shandong Peninsula.

Spatial distribution and reconstruction potential of Japanese anchovy(Engraulis japonicus) based on scale deposition records in recent anaerobic sediment of the Yellow Sea and East China Sea

Many studies have revealed that anchovy has exhibited large variability in population size on decadal tim-escales. However, such works concerning anchovy population are mainly based on short historical catch records. In order to understand the causes of variability in fish stocks （natural and/or anthropogenic） and calibrate the error between catches and standing stocks, it is essential to develop long-term time series of fish stocks from the time when human impacts are minimal or negligible. Well preserved fish scales from sediment record are regarded as useful indicators revealing the history of fish population dynamics over the last centuries. Anchovy scales was first analyzed over the Yellow Sea and East China Sea and the largest abundance was found in the central South Yellow Sea where is regarded as the largest overwintering ground for Japanese anchovy （Engraulis japonicas）. Thus in the central South Yellow Sea, two cores covering the last 150 years were collected for estimating fish scale flux. The scale deposition rate （SDR） records show that the decadal scale SDRs were obviously coherent between cores with independent chronologies. Thecalibration of downcore SDRs to the standing stocks of anchovy further validated that SDR is a reliable proxy to recon-struct the long-term anchovy population dynamic in the central South Yellow Sea where anoxic conditions prevail in the sediment. When assembled with other productivity proxies, it would be expected that SDR could be associated with changes in oceanic productivity and may make a contribution to determine the forcing factors and elucidate the mechanism of the process in future.

Genetic variation within and among range-wide populations of three ecotypes of the Japanese grenadier anchovy Coilia nasus with implications to its conservation and management

Studies of range-wide populations can contribute to the comprehension of the relative roles of historical events and contemporary factors that influence genetic variation within and among populations.Japanese grenadier anchovy,Coilia nasus,is a commercially important fish,which widely distributes in the Changjiang River,the coasts of China and Korea,and the Ariake Sea of Japan.This species exhibits three life-history strategies(anadromous,landlocked and freshwater resident forms).Using two fragments of nuclear DNA,genetic variation within and among 18 populations across the rivers and coast of China and Ariake Sea of Japan was examined.Patterns of genetic diversity and divergence among populations varied widely across C.nasus'range,and indicated the different effects of historical events and anthropogenic factors.Strong genetic divergence between freshwater resident populations and other populations suggested that historical geographical factors greatly influenced the genetic structure of C.nasus.Significant genetic differentiation observed among lakes in lower Changjiang River and Huaihe River might be probably influenced by hydraulic facilities.The population genetic structure among the three ecotypes revealed in the present study indicated an important role for environment variation,and the factors responsible for shaping C.nasus different life history strategies might also impact population structure.

Carbon, nitrogen and phosphorus stoichiometry in Japanese anchovy (Engraulis japonicus) from the Huanghai Sea, China

Generally, nutrient cycle is closely related to the element distribution in biomass and the popula- tion dynamics in ecosystems. Carbon, nitrogen and phosphorus in Japanese anchovy （Engraulis japonicus） of different body lengths from the Huanghai Sea （Yellow Sea） were determined to better understand their variability and reasons during its life history. The mean content was 45.12%, 10.12% and 2.02% for C, N and P, respectively. Significant differences in C, N and P elemental composition were found among different sizes, which could be explained by varying proportions of storage compounds in whole body fish, and varying degrees of ossification. Considering abun- dant resources in Japanese anchovy, it was an important P-pool in the cycle of P. Moreover, the excreted N/P ratio was significantly different in fishes of different sizes, especially at high gross growth efficiency. In the past two decades, overexploitation tended to cause smaller body length in the community structure of anchovy, which presumably changed the nutrient cycle in food webs of the Huanghai Sea. Exptrapolation of the results indicates that Japanese anchovy may be important for conveying nutrient in the Huanghai Sea.

Bleaching with the Mixed Adsorbents of Activated Earth and Activated Alumina to Reduce Color and Oxidation Products of Anchovy Oil

Fish oil is a rich source of polyunsaturated fatty acids,and its refinement has drawn attention for years.An appropriate adsorbent can effectively remove the pigment impurities in the fish oil.This study evaluated the impact of different absorbents on the reduction of oxidation products and color of anchovy oil during the decolorization under high vacuum.Using the single factor design,four process parameters including adsorbents type,adsorbent amount,temperature and time were tested to determine the optimum decolorization parameter.The results showed the optimum decolorization conditions were that the fish oil was treated with 8%acti-vated alumina at 80℃for 40 min.In the central group experiment,the addition amounts of mixed absorbents(activated earth and activated alumina),including the mass ratio of adsorbent in oil(5%-11%,w/w)and the mass ratio of activated earth in total absor-bent(20%-80%,w/w)were optimized to remove the oxidation products.Under the optimum condition at 10.18%of adsorbent and 70%of activated earth,the total oxidation value(TOTOX value)showed the minimum with the 44.4%of removal rate.Eight metal elements were analyzed in decolorized oil using inductively coupled plasma mass spectrometry(ICP-MS).The removal rates of Zn and Pb were 94.12%and 55.35%,respectively.The decolorization process using mixed absorbents under appropriate condition can significantly reduce the oxidation products and pigments in fish oil,which will benefit the industrial production of fish oil.

Response of Japanese anchovy(Engraulis japonicus)to the Pacific Decadal Oscillation in the Yellow Sea over the past 400 a

Quantitative identification of long-term changes in the abundance of Japanese anchovy(Engraulis japonicus)in the Yellow Sea is particularly important for understanding evolutionary processes of the Yellow Sea ecosystem.Unfortunately,the driving mechanisms of climate variability on the anchovy are still unclear due to the lack of long-term observational data.In this study,we used the fish scale deposition rate in the central Yellow Sea to reconstruct the time series of the anchovy stock over the past 400 a.On this basis,we further explored the impacts of the Pacific Decadal Oscillation(PDO)on the anchovy.Our results show that the anchovy stock is positively correlated with the PDO on a decadal time scale.In addition,anchovy abundance was relatively high during1620–1860 AD(the Little Ice Age,LIA),though in a state of constant fluctuation;anchovy abundance maintained at a relatively low level after~1860 AD.In particular,followed by overfishing since the 1980 s,the anchovy stock has declined sharply.Based on these findings,we infer that fluctuations of the anchovy stock may be regulated by basin-scale“atmosphere–ocean”interactions.Nevertheless,the role of overfishing should not be ignored.

Oceanographic Condition in the Distribution Areas of Anchovy Engraulis Japonicus in the Yellow Sea and East China Sea

Based on the data obtained from the cooperative surveys by China and Norway from 1984 to 1994, this paper deals with the hydrographic characteristics of didribution areas of anchovy in the Yellow Sea and East China Sea from November to May. The relationships between distribution of anchovy and hydro-graphic environment are also analysed in this paper. The main research findings are briefly given below. (1) From November to March, the water temperature continually decreases and meanwhile the dense areas of anchovy move from north to south. The high schooling areas of anchovy are mainly distributed in the warm of cold front areas with temperature of 11-13℃. (2) In November and December, the Yellw Sea cold water-mass exists roughly between 50m depth and sea bottom. The thermo-balocline is approximately located at the 30 ~ 50m depth and the anchovy is usually distributed above the thermo-halocline In January and March, the Yellow Sea cold watermass disappears and the fish schools are distributed at the

Experimental study on drying kinetics of anchovy using centrifugal fluidized bed technique

The present study investigated the drying kinetics of anchovy experimentally using centrifugal fluidized bed technique.The main purpose was to experimentally investigate the effect of the inlet air temperature on the drying kinetics of anchovy in a centrifugal fluidized bed dryer,to fit the experimental data to the widely used mathematical models of drying.Further,the effective moisture diffusivity and activation energy in anchovy drying were investigated in the current work.The drying experiment was conducted at drying air temperatures ranging over 70-120°C.The air velocity and rotating speed of the air-distributor were fixed at 1.5 m/s and 150 r/min,respectively.Pressure drop across bed was approximately 390 Pa,while the layer height was fixed at approximately 2 cm.The anchovies were dried starting from 412%db down to 16%db;drying time ranged from 64 min to 172 min.It was found that the drying temperature was a significant factor in decreasing the moisture content,moisture diffusivity and drying time.The moisture diffusivity and activation energy were investigated at 0.11×10-9-0.25×10-9 m2/s and 20.32 kJ/mol,respectively.When compared to existing models,the Midilli model proved to be in good agreement with change in moisture ratio.

气相色谱-燃烧-同位素比值质谱法测定鳀鱼肌肉组织中单体氨基酸的碳稳定同位素组成

The stable carbon isotope compositions of individual amino acids in muscle tissues of the anchovy, Engraulis japonicus, a key species of animal in the Yellow and the East China Sea ecosystem, were determined by the gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). Eleven amino acid compounds were identified and their δ(13C) values were successfully measured. The new ability to measure stable carbon isotope compositions of individual amino acids offers a potential method for understanding digest, absorption and metabolism of anchovy, Engraulis japonicus, pathway of carbon transfer through food web and evaluating trophic quality of diet.

The Signatures of Stable Isotopes δ^(15)N and δ^(13)C in Anadromous and Non-Anadromous Coilia nasus Living in the Yangtze River, and the Adjacent Sea Waters

Stable isotopes are increasingly used to investigate seasonal migrations of aquatic organisms. This study employed stable isotopes(δ^(13) and δ15N) for Coilia nasus from the lower Yangtze River and the adjacent East China Sea to distinguish different ecotypic groups, ascertain trophic nutrition positions, and reflect environmental influences on C. nasus. δ^(13)C signatures of C. nasus sampled from Zhoushan(ZS), Chongming(CM), and Jingjiang(JJ) waters were significantly higher than those from the Poyang Lake(PYL)(P < 0.05). By contrast, δ^(15)Nsignatures of C. nasus in ZS, CM, and JJ groups were significantly lower than those in PYL group(P < 0.05). Basing on δ^(13) and δ^(15)Nsignatures, we could distinguish anadromous(ZS, CM, and JJ) and non-anadromous(PYL) groups. The trophic level(TL) of anadromous C. nasus ranged from 2.90 to 3.04, whereas that of non-anadromous C. nasus was 4.38. C. nasus occupied the middle and top nutrition positions in the marine and Poyang Lake food webs, respectively. C. nasus in Poyang Lake were significantly more enriched in δ^(15)N but depleted in δ^(13), suggesting that anthropogenic nutrient inputs and terrigenous organic carbon are important to the Poyang Lake food web. This study is the first to apply δ^(15)Nand δ^(13) to population assignment studies of C. nasus in the Yangtze River and its affiliated waters. Analysis of stable isotopes(δ^(15)Nand δ^(13)) is shown to be a useful tool for discriminating anadromous and non-anadromous C. nasus.

Exploitation Patterns of Anchovies (Engraulis encrasicolus) by Marine Artisanal Fisheries in Togo (West Africa)

Pelagic fish,including sardines and anchovies(Order Clupeiformes),are the most common species taken by artisanal marine fisheries along the Togolese coast.We investigated fisher involvement as well as fish captures over a period of 10 years,particularly of the European anchovy(Engraulis encrasicolus).Our results indicate that 60%of fishers operated from the Loméfishing harbour,most fishers being Ghanaians working seasonally in Togo.63.7%of all the fishers used canoes with outboards,a higher percentage compared to the previous decades.Seven fishing gear type were identified,with bottom gillnet and surface gillnet being the most commonly used.However,in the most important fishing camp in the country in terms of fish production(Loméfishing harbour),all fishers used shark nets.Overall,fisheries catches did not change significantly across years,but anchovy fishing effort and catch per unit of effort(CPUE)declined over the study period,suggesting some depletion of the species stocks on the Togolese coast and a demotivation of fishers.