Abstract:Formation of unreduced eggs has been reported in several interspecific hybrids of teleosts.These results suggested that a genomic conflict due to a hybrid event may trigger an atypical mode of reproduction,such as formation of unreduced gametes.The diploid gynogenetic progenys of allotetraploid hybrids of red crucian carp(Carassius auratus var.red)×common carp(Cyprinus carpio L.)(abbreviated as G)produced diploid eggs,which have been identified by chromosomal counting of germ cells,fertilization observation of gametes and ploidy detection of progeny.In this paper,DNA contents and cytological studies on oogenesis of G was detected by Flow Cytometry,tissue sections and chromosomal observations,with dipoid red crucian carp as controls.The results showed that the DNA contents of oocytes in G were showed with two main peaks.The peak one with the lower value was consistent and the other peak value was double with that of oocytes in RCC,which were deduced as different type of primary oocytes by tissue sections observations and chromosomal observations.The oocytes with lower peak values showed the mainly smaller volume of primary oocytes,in which there were some cavitation-like abnormal oocytes,exhibiting partical pairing at the pachytene stage,they were deduced as the primary oocytes without chromosomal doubling.Such other oocytes with higher peak values showed a few larger volume of primary oocytes in stage Ⅱ,which could perform normal development with normal chromosomal pairing in meiosis Ⅰ,and were deduced as the primary oocytes with chromosomal doubling.The results enriched the research data of mechanism of unreduced gametes,being of great significance in fish genetic breeding.

Abstract:Gynogenesis was induced in red bighead carp(Aristichthys nobilis red var.)eggs using the UV-irradiated diploid sperm of allotetraploid hybrids,which were derived from crossing of red crucian carp(♀)×common carp(♂),with cold shock treatment in 4-6 ℃ water for 11-13 min to make chromosome doubled.Different initiation time of treatments resulted in two types of diploid gynogenetic red bighead carp:meiotic gynogenetic(meiG)and mitotic gynogenetic(mitG).The survival rates of meiG and mitG were 19.4%±2.3%,7.3%±1.9% respectively.The gynogenetic fish were confirmed by morphological characteristics,chromosome counting,and microsatellite DNA analysis.The results showed that both meiG and mitG gynogenetic fish were identified as diploid with 48 chromosomes,which produed exclusively bands being same as that in maternal parents and discriminated from that in allotetraploid hybrids by microsatellite DNA analysis.All the gynogenetic fish were female,89% of which showed normal ovary development.It provided important data for suggesting XX genotype in female red bighead carp.In addition,the body color of gynogenesis offspring(gynogenetic red bighead carp(♀)×wild red bighead carp(♂))was redder than that in wild red bighead carp.The formation of gynogenetic red bighead carp should be a valuable contribution to body color non-degradation,genetic improvement in fish breeding,as well as sex determination researches in fish.

Abstract:Slr0351 is an unknown protein and its homologs exist widely in many cyanobacteria and iron-sulfur bacteria.We constructed pET-slr0351 and expressed Slr0351 successfully in E.coli BL21.Using affinity chromatography purification,we obtained purified Slr0351.Under anaerobic conditions,Slr0351 was brown and had absorption peak at 460 nm,which was the characteristic absorption peak of 2Fe-2S cluster.The brown Slr0351 is sensitive to oxygen and could be reduced with sodium dithionite,showing that Slr0351 was iron-sulfur protein.By homologous double-crossover,slr0351 was replaced by Kana,resulting in the knockout mutant of Synechocystis sp. PCC 6803,Δslr0351.Via scanning the absorption spectra of Δslr0351 and WT with ultraviolet-visible spectrometer,we found that chlorophyll a content of Δslr0351 is only 68.8% that of WT under the medium light condition.The depletion of slr0351 reducing the content of chlorophyll a in Synechocystis cells.Compared the growth rate of cyanobacteria under different culture conditions,Δslr0351 showed the following changes compared to the wild type:(1)more sensitive to sulfur and iron starvation;(2)lower efficiency of light utilization and lower growth rate under LL conditions,which is related to the lower content of chlorophyll a in Δslr0351.This paper is beneficial to gene function research of Cyanobacteria,and provides a certain reference value for the treatment of Cyanobacteria bloom and pollution in freshwater.

Abstract:Gracilariopsis lemaneiformis is an important agarophyte,which is economically important.The industrialization of Gracilariopsis lemaneiformis started 20 years ago and has become one of the most important aquaculture in China.At present,the breeding of this species depends heavily on selective and other traditional breeding approaches.The molecular breeding system which is more efficient has not yet been established.The construction of genetic linkage map is urgent for the molecular marker assistant breeding and mapping of quantitative traits.Totally 400 pairs of SSR primers and 91 pairs of RSAP primer combinations were screened for parents of two mapping populations to provide polymorphic molecular markers for the construction of genetic linkage map.The genetic distances among four parents were evaluated.15 polymorphic markers between GL-F3 and GL-M8 and 8 polymorphic markers between GL-F6 and GL-M9 were obtained by SSR screening.88 polymorphic markers between GL-F3 and GL-M8 and 93 polymorphic markers between GL-F6 and GL-M9 were obtained by RSAP screening.The development of these markers set the basis for construction of genetic linkage map.The genetic distance revealed by SSR between GL-F3 and GL-M8 was 0.071 2,while that between GL-F6 and GL-M9 was 0.043 6 and the genetic distance revealed by RSAP between GL-F3 and GL-M8 was 0.228 4,while that between GL-F6 and GL-M9 was 0.253 7.The average covering loci and producing polymorphic of per primer combinations were much higher from RSAP than from SSR analysis,the RSAP is 4.48 times and 12.13 times of SSR between GL-F3 and GL-M8,respectively while it showed 5.81 times and 25.5 times between GL-F6 and GL-M9,respectively.RSAP markers were better than SSR in evaluating the genetic distance and genetic diversity of resources of G.lemaneiformis.The genetic difference among parents of mapping population of G.lemaneiformis was proved.The development of SSR and RSAP markers set a foundation for the construction of genetic linkage map.The study revealed low genetic diversity in this species and other approaches,such as mutagenesis,cell engineering and transgenic were suggested to be exploited in further breeding attempts.

Abstract:Hybridization(interspecific hybrid)has been used in numerous species to increase growth rate,manipulate sex ratios,produce sterile animals,improve flesh quality,increase disease resistance,improve environmental tolerance and improve a variety of other desirable traits to make aquaculture more profitable.GIFT(Genetically Improved Farmed Tilapia)strain Nile tilapia is the main kind of cultured tilapia,which has many advantages such as rapid growth rate and high fillet yield.However,GIFT tilapia has poor disease resistance capability to Streptococcus iniae infection,which may be related to too much inbreeding.Breed improvement by interspecific hybrid may enhance disease resistance capability in tilapia.A complete diallel mating system between GIFT tilapia and O.aureus and additive-dominant genetic model were used to analyze heterosis of 8 growth-related traits,genetic effect and correlation of traits.At the time of day 100 over the experiment,the results indicated that:(1)Heterosis of growth related traits in F₁ hybrid varied from 0.129 4 to 0.368 4,and population heterosis over parent mean(H_pm)of these growths related traits were all positive in F₁.In addition to caudal peduncle length(CPL),other growth related traits have negative or insignificant positive population heterosis over parent better(Hpb);(2)The general heritability in the broad sense(H_B)with 0.714 2-0.995 3 indicated that genetic variations of all 8 traits were significantly influenced by additive effect and dominance effect(P<0.01),whereas,the narrow sense of growth-related traits except CPL varied from 0.469 4 to 0.737 9,and indicated additive effect controlled the genetic variation of output value;(3)The phenotypic correlations 0.776 6-0.999 7 and genetic correlations 0.994 1-1.000 0 between body weight,body length,total length,body width,body height,head length,caudal peduncle length and caudal peduncle height,were all highly statistically significant(P<0.01).Furthermore,after sampling,experimental fish were infected with 3.95×10⁶ CFU/mL S.iniae through abdominal cavity.F₁ generation of GIFT tilapia purebred combination died 12 h later,whereas F₁ generation of Aureus tilapia purebred combination died 192 h later.384 h after infection,mortality of F₁ for GIFT purebred combination was 40%,while mortality of the reciprocal cross combinations was 20% and 23.3% respectively.The lowest mortality(6.67%)was found in F₁ for Aureus purebred combination.Overall,the results indicate that,except CPL,other growth related traits have no heterosis; however,hybridization can improve the disease resistance of breeding offspring.

Abstract:The present study explored the differences in growth,survival and inbreeding depression among selected population,inbreeding population and imported population.Inbreeding population was constructed by full-sib mating of selected population in Litopenaeus vannamei.A standard procedure was used in family construction.Individuals of three populations were tested in the same environment.The growth experimental results showed that,body weight of selected population was significantly higher than those of inbreeding population and imported population(P<0.05).At day 60,body weight of selected population increased by 7.11% and 20.01%,compared with those of imported population and inbreeding populations.Different growth performance was observed among different families and in different population.The body weight of 6012 was biggest in selected population,AGR and SGR is 0.29 g/d and 31.82% higher than the mean of the families,and 61.11% higher than that of the lowest.And the body weight of family 6008 was biggest in imported population,AGR and SGR is 0.33 g/d and 3.17%/d,which was 65% and 33.19% higher than the mean of the families,and 230% and 128.06% higher than that of the lowest.The survival results indicated that the difference of survival between selected population and imported population was not significant(P>0.05),but that was significant(P<0.05)between selected population and inbreeding population,12.74% higher than inbreeding population.Full-sib matings revealed that the amount of inbreeding depression of body weight were 16.68% and 10.76%,and inbreeding depression of survival were 11.30% and 10.54%,compared with selected population and imported population.The estimated average inbreeding depression coefficient of body weight was -6.60% and -4.30% per 10% increase of inbreeding coefficient.These results suggest that selection works well in the breeding program of Litopenaeus vannamei,and inbreeding especially full-sib matings should be avoided in the future breeding programs.

Abstract:Consistent individual differences(CIDs)in phenotypes,such as morphology,physiology and behaviour,are a surprisingly widespread phenomenon in most taxa of the animals.CIDs are individual differences in phenotype that are maintained over time(e.g.as measured by repeatability)and across contexts.Many studies showed that a potential linkage between standard metabolic rate(SMR)and other physiological traits(active metabolic rate and aerobic metabolic scope)exists among different taxa of the animals.To examine the effects of starvation on the intraspecific variation and repeatability of locomotion metabolism in a carnivorous fish,the juvenile southern catfish(Silurus meridionalis Chen)which is distributed widely in the Changjiang River and other water areas,was selected as the experimental fish.The resting metabolic rate(MO_2rest)and active metabolic rate(MO_2active)of both the starvation group[(12.15±0.14)g,n=29,starved for two weeks]and control group[(12.00±0.23)g,n=28,fed with 4%-5% body weight rice field eel meal every other day]were determined in trial Ⅰ(before starvation)and trial Ⅱ(after starvation)at(25±0.5)℃.Additionally,the aerobic metabolic scope(AMS=MO_2active-MO_2rest),cost of transports(COT)and optimal swimming speed(Uopt)were also calculated during the course of the experiment to evaluate the adaptive strategy of locomotive metabolism in this fish species during food fluctuation.The results of our study showed the MO_2rest,MO_2active and AMS of the starvation group decreased significantly by 8.6%,36.3和44.1%,respectively,compared to trial Ⅰ,whereas the MO_2rest of the control group increased by 25.9% and its MO_2active did not change during the course of experiment.This unparalleled change resulted in a 12.6% decrease in AMS in the control group in trial Ⅱ.The coefficient of variance(CV)of the MO_2rest in the starvation group decreased while CV of the MO_2active and AMS increased in the same group.However,the corresponding index of the control group changed in a negative direction.The repeatability percentages of the MO_2rest,MO_2active and AMS in the starvation group were all lower than those in the control group.The slope of linear regression equation for correlation between locomotor oxygen consumption rate(MO₂)and swimming velocity in the starvation group did not change between two trials while the intercept of linear equation reduced profoundly.However,both the slope and intercept did not change in the control group between two trials.Starvation triggered a significant reduction in the repeatability in the locomotor MO₂ in the S.meridionalis.The COT_min and Uopt reduced significantly by 25% and 11.3% in the starvation group,respectively.However,the control group showed a smaller decrease in the COT_min and Uopt which reduced by 8% and 4.8%,respectively,when compared to the starvation group.Our study suggested that the juvenile S.meridionalis not only exhibited the significant repeatability in MO_2active,AMS and locomotor MO₂ with the exception of MO_2rest,but also decreased the optimal swimming speed and hence improved the swimming efficiency when this fish species was facing the low food availability conditions.Integrative regulation in swimming metabolic strategy in the southern catfish may be an adaptive consequence in a fluctuating food resources environment,and may result in an increase of survival for this fish species.

Abstract:To understand the impact of farming mode on digestive enzyme activity of tilapia,we selected three familiar breeding patterns in Guangdong province,i.e.traditional farming mode(M1),twice harvest a year farming mode(M2)and polyculture of fish and shrimp farming mode(M3).We performed water quality monitoring and digestive enzyme activity detection through the four months observation.M2 model showed the highest stomach protease activity(SPA)in both 1^st and 2^nd months.M1 mode displayed the highest intestinal protease activity(IPA)during the whole observation period.For the hepatopancreas protease activity(HPPA),M2 mode was rather high in the 2^ndmonth as well as the 3^rd month,while M3 model showed the highest level in both 1^st and 4^th months.In terms of each model,the protease activity displayed in the order of IPA>SPA>HPPA.Lipase activity and amylase activity of intestine and hepatopancreas were overall highest in M2 mode.The ability of protein digestion of tilapia in different organs is different,but no significant difference for total protein digestion ability among the three breeding patterns.On the other hand,M2 mode showed advantage in digestion of fat and starch which would reduce the demand of protein in feed composition and further improve the feed conversion ratio and cut down the cost of feed.

Abstract:To investigate the effect of different delayed first feeding time on the amino acids and fatty acids of Myxocyprinus asiaticus larvae under the condition of water temperature(19±0.5)℃,we divided the larvae into 7 different initial delayed feeding time groups,1,3,5,7,9 and 11 delayed days denoted as group D0,D1,D3,D5,D7,D9 and D11 respectively,and subsequently fed at corresponding time,then detected the composition and content of the amino acids and fatty acid at different intervals,with total experimental period lasting 29 days.Results showed that,(1)The larvae body lipid content showed a significant downward trend when prolonging the starvation time.However,at the end of the experiment(29 days old),all of the other groups were not significantly different from the control group on lipid content,indicating a complete compensation effect.(2)During starvation,the monounsaturated fatty acids(MUFA)were utilized as energy substrates by M.asiaticus larvae,with the order of n-6>n-9>n-3 and C22∶6n-3(DHA)being preserved prior to C20∶5n-3(EPA).In addition,the contents(percentage)of DHA and ARA were significant different from the body weight and moisture content.(3)With increasing time of starvation,the alanine,isoleucine,leucine and histidine decreased significantly,while the aspartic acid and glutamic acid increased significantly,however,the glycine,lysine and arginine first increased and then decreased in M.asiaticus larvae.To sum up,first,M.asiaticus larvae have strong adaptability for starvation,and mainly consume lipids in the early starvation period,and then amino acids begin to be consumed when the lipids come near to the threshold.Then,it suggested a slower restoration of the amino acid than the fatty acids for M.asiaticus larvae after resuming feeding.

Abstract:A 9-week feeding experiment was conducted to evaluate the effect of dietary vitamin A level on growth and serum biochemical parameters for juvenile Japanese seabass,Lateolabrax japonicus.Six groups of isonitrogenous(43% crude protein)and isoenergetic(20 kJ/g dry matter)purified diets(Diets 1-6)containing 245,1 005,1 835,3 781,7 583 and 15 273 IU vitamin A(supplied as retinyl acetate)per kg diet were fed twice daily to triplicate groups(10 fish/group)of fish[initial weight(10.20±0.14)g/fish]in 120 L plastic tanks.Fish fed the basal diet(Diet 1)developed heavy mortality,exophthalmos,haemorrhages at the base of the fins and distortion of operculum.None of these deficiency signs were observed in fish fed the vitamin A supplemented diets(Diet 2-6).Carcass lipid content significantly increased with dietary increasing vitamin A level,while protein and moisture showed no significant differences.The analyses of serum parameters showed that the activity of alkaline phosphatase(AKP),the content of triacylglycerol(TG)and total cholesterol(TC)all significantly increased with the increase of dietary vitamin A level,while the activities of glutamate transaminase(ALT)and aspartate aminotransferase(AST)had the reverse trend.Broken-line regression analysis of weight gain or liver vitamin A content showed that juvenile Japanese seabass require a minimum of 1 934.8 IU vitamin A/kg diet for maximal growth or 3 546.6 IU vitamin A/kg diet for maximal liver vitamin A deposition.

Abstract:Selenium yeast(SY)and tea polyphenols(TP)belong to high-quality natural antioxidants.As an organic selenium source,SY has the effects on both promoting growth and improving product quality.TP is a term for polyphenols in tea,which is helpful to induce growth,improve product quality and enhance immunity.In the present study,a two-factorial and three-level experiment was designed to evaluate the effects of dietary SY,TP and their combination on the growth performance,the nutritional composition in muscle and the ability to resist Aeromonas hydrophila in juvenile Wuchang bream,Megalobrama amblycephala[mean weight(1.75±0.01)g].Totally nine semi-purified diets were formulated to provide graded levels of SY 0,0.25,0.50 mg/kg and TP 0,50,100 mg/kg.After 60 days' feeding,the growth performance,muscle composition,biochemical parameters of serum and liver,related gene transcription in the hypothalamus-pituitary-growth axis as well as survival rates after being infected with A.hydrophila were investigated.The results showed that dietary SY and TP significantly improved the weight gain rate(WGR),specific growth rate(SGR)and the content of protein in muscle(P<0.05),while reduced the food conversion ratio(FCR)significantly(P<0.05).Both dietary SY and TP significantly enhanced the growth performance by upregulating the mRNA expression of growth related genes in the hypothalamus-pituitary-growth axis.The difference is that SY mainly upregulated the mRNA expression of MaGH and MaIGF-I significantly(P<0.05),whereas TP enhanced the transcription of MaGHR₂ and decreased the mRNA level of MaIGF-I significantly(P<0.05).Consequently,dietary SY significantly enhanced the contents of GH and IGF-Ⅰ in the serum,whereas TP decreased serum IGF-Ⅰ levels significantly(P<0.05).No significant interaction effect of dietary SY and TP on serum GH and IGF-Ⅰ was observed in juvenile Wuchang bream(P>0.05).Both dietary SY and TP significantly enhanced the crude protein content in the muscle(P<0.05).And there was no significant interaction effect of dietary SY and TP on the content of the crude protein in the muscle(P>0.05).Both dietary SY and TP could improve the ability to resist A.hydrophila.And there was an interaction effect of SY and TP on the ability to resist A.hydrophila.In light of the above,it could be concluded that a basal diet supplemented with 0.50 mg/kg of SY and 50 mg/kg of TP could help keep better growth performance and disease resistance in juvenile Wuchang bream.

Abstract:To understand the lipid state accumulated in livers of cultured Carassius auratus and clarify the functions of body indices in evaluating the lipid accumulation of liver,body indices including condition factor(CF),ratio of body weight to body length(W/L),viscerosomatic index(VSI),heptosomatic index(HSI),mesenteric fat index(MFI)and intestinal index(II)of thirty wild C.auratus and sixty cultured C.auratus were calculated and liver lipid content was determined by Soxhlet method.The morphology of hepatic cell was observed by method of hematoxylin and eosin stain.Relationships between body indices and liver lipid content were studied by software SPSS 19.0.Results showed that all the CF,W/L,VSI,HSI,MFI and II of cultured C.auratus were higher than those of wild C.auratus. The average liver lipid contents of wild and cultured C.auratus were 1.88%±0.69% and 19.49%±4.31%,respectively.Hepatic histology showed that hepatic cells,arranged along the hepatic cell cords,of wild C.auratus were uniform in size and most nuclei were located in the central,which indicated the normal morphology of hepatic cells.However,hepatic cells of cultured C.auratus were irregular in size and morphology,characterized by obvious nuclei migration,atrophy,unclear outline and more fat vacuoles.No significant relationship between CF and liver lipid content of cultured C.auratus was found(P>0.05).However,VSI(X₁),HSI(X₂)and MFI(X₃)all were significantly and positively related to the liver lipid content(Y)(P<0.05),and the regression equation was as follows:Y=8.085+0.282 X₁+3.726 X₂+0.505 X₃(R=0.562,F=3.995,P=0.018).It is concluded from the above that the liver lipid accumulation is very serious.The higher the VSI,HSI and MFI of cultured C.auratus,the more severe of lipid accumulation in the liver.

Abstract:Largemouth bass(Micropterus salmoides)has become one of the important famous freshwater fishes in China since the success of their artificial breeding in 1985.However,iced trash fish from offshore is still the main feed during the culture process of largemouth bass,and long-term use of iced trash fish not only puts pressure on the resources and environment,but also brings some of the original ocean pathogenic microorganisms into freshwater aquaculture area.Replacement of iced trash fish by artificial feed is an inevitable trend in the industrial development of largemouth bass,but in fact,the progress of extensive use of artificial feed has been slow.It's reported that demand for fish feed or nutrition is closely related to composition of the intestinal flora of fish,and differences of fish diets also affect the composition of fish intestinal microflora.So,to explore the nutritional needs and feed configuration of largemouth bass,based on intestinal microflora,is a valuable new exploration.In this paper,intestinal microflora of different largemouth bass including feeding iced trash fish and artificial diet were examined to assess intestinal bacteria community structure using the technology of PCR-denatured gradient gel electrophoresis(PCR-DGGE).The results showed that,microflora composition similarity between iced trash fish group and artificial diet group was 24%.Compared with the iced trash fish group,the diversity of intestinal microflora of artificial diet group decreased.The analysis of the common and specific bands from two groups of largemouth bass demonstrated that,the common intestinal bacteria of both groups include Rhodospirillaceae,Clostridium,Cyanobacterium,Edwardsiella hoshinae and Stenotrophomonas maltophilia; the specific intestinal bacteria of iced trash fish group were Bacteroides,Carnobacterium,Weissella and Plesiomonas; the specific intestinal bacteria of artificial diet group were Flavobacterium,Cetobacterium somerae,Leuconostoc citreum,Brevundimonas diminuta.In sum,compared with iced trash fish,artificial diet reduced the diversity of intestinal microflora and also inhibited the quantity of probiotics of largemouth bass.It's speculated that slower growth of largemouth bass feeding artificial diet may be related to the decline in the ratio of Bacteroides to Firmicutes.The results of this study suggested that,in the future,the probiotics such as Bacteroides could be added to artificial diet for improving absorption of artificial diet,and further promoting the growth and nutritional absorption of largemouth bass.

Abstract:During August and September of 2013,a serious infectious disease characterized by body ulcer,internal organs haemorrhage and nodules showing on epicardium occurred in Acipenser baerii in Hanyuan Lake,Ya'an,Sichuan Province.To elucidate the aetiology,the bacteria isolated from the livers,spleens and kidneys,and artificial infection,physiological and biochemical analysis and molecular analysis of the isolate were conducted.The results showed that a Gram-positive,chain-forming coccus(Ab130920)was isolated and the strain was lethal to A.baerii.Physiological and biochemical characteristics were consistent with Streptococcus iniae(ATCC29178);the 16S rRNA gene sequencing analysis by Blast in GenBank indicated that the isolate(KJ162337)showed high levels of similarity to S.iniae(99%); A phylogenetic tree was constructed based on the 16S rDNA sequences of the isolate and the homologous sequences of other strains of Streptococcus,and the strain and other S.iniae strains formed a tight cluster; Meanwhile,expected segment of 870 bp was yielded in the specific PCR detection of S.iniae based on S.iniae lctO gene.As expected,the strain Ab130920 was positive by multiplex PCR for all five virulence genes(cpsD,simA,sagA,pdi and scpI)test,showing amplification products of the expected sizes,which was further identical the isolate to S.iniae and confirmed the pathogenicity of it,and consistent with the result of artificial infection.The drug sensitivity results showed the isolate was sensitive to amoxicillin,doxycycline and florfenicol,etc. but resistant to novobiocin,ofloxacin,rifampicin.

Abstract:To explore the mechanism of change in flavor quality of post-harvested commercial bivalve molluscs,a trial study for bottom-raised scallop(Patinopecten yessoensis)was carried out.Two 7-day-long trial supply chains for live products were designed with reference to the current operation in the scallop industry,which were immersed(wet-chain)and non-immersed(dry-chain),respectively.Sensory attributes,physical characteristics and physiological condition of scallop were tracked by daily testing of adducors separated from live scallop sampled.Flavor profiles were described by sensory evaluation with 5 aspects of sensory indexes(odor,taste,aftertaste,texture and appearance),FAA(free amino acids),ATP and its breakdown products,Glycogen,CI(condition index),Shear Force and Cooking Loss were selected as quality condition indicators of live scallop.Principal Component Analysis(PCA)was used to identify outliers between the sensory evaluations of each sample.To interpret the flavor attributes developed during supply chains,relationships between the sensory properties and lab measurements were determined by partial least squares regression analysis(PLS2).Results showed that,during early stage of both supply chains,severe stress induced by harvest and post-harvest led to a temporary decrease of the flavor quality,and much less palatable descriptors(bitter,sour)appeared; During middle stage of the both supply chain,scallop live in a relatively stable environment,the main flavor profile contributors were palatable descriptors(sweetness,umami and seafood); in the late stage,less palatable descriptors(bitter,sour)appeared again;totally,quality condition of live scallop tended to decline,indicated by the measurement of physicochemical indexes selected;comparing wet-chain with dry-chain,short-term transportation(≤2 days)in the dry-chain has superiority over wet chain on both sensory characteristics and physiological conditions,when extending transportation period(≥3 days)wet-chain showed some advantages;result of the correlation between sensory and physicochemical indexes showed that,sensory descriptors(sweet taste,umami aftertaste,dairy odor)and physicochemical indicators(Gly,Glu,Arg,ATP,AEC,CI)could distinguish the difference of scallops sampled along the supply chains with different flavor attributes,and could provide a reference for scientifically characterizing the flavor variation discipline of scallops along the live supply chain.

Abstract:At present,many scientists pay more attention to the incidental catch of top predator of food chain in longline fisheries,such as sharks,sea turtles and sea birds.Given the long life span and relatively low reproductive capacity of many shark species,reducing the incidental catch of sharks during commercial fishing operations is thus critical in the conservation of shark species.In 1999,FAO promulgated the International Plan of Action for the Conservation and Management of Sharks.In order to protect the marine environment and conserve the shark species,many countries and regions declared a law prohibiting commercial shark fishing in its national waters.Shark's habitat environment is complex with respect to both spatial and temporal variations.Mechanisms of their migration are not fully understood even though many studies suggested that they might be related to the behavior and dynamics of zooplankton.The effective fishing gears and methods to mitigate the incidental catch rate of Carcharhinus falciformis and the effects of 16/0 and 18/0 circle hooks to the incidental catch rate of C.falciformis should be studied further.Based on these studies,the robust results could be obtained and could be used to reduce the incidental catch rate of C.falciformis effectively.On the other hand,there were many studies about the biological characteristics of C.falciformis,but the studies about the impacts of marine environment on the incidental catch rate of C.falciformis were rare.The aim of this study is to reduce the incidental catch rate of C.falciformis in longline fisheries.In this study,the mean nominal catch rates of C.falciformis and environmental variables were obtained from two longlining surveys in waters near Gilbert Islands from 4 October 2009 through 25 December 2009 and from 20 November 2010 through 20 January 2011.Data included:hook depth data,temperature,salinity,dissolved oxygen concentration and chlorophyll concentration vertical profile data,operating parameters,catch statistics.Stepwise regression was used to develop the hook depth calculation model.Wilcoxon-test was used to test if there were significant differences among C.falciformis incidental catch rates of four kinds of fishing gear or hook types.Statistics and clustering analysis were used to analyze environmental effects on the C.falciformis catch rate.Results showed that:(1)C.falciformis incidental catch rate can be significantly reduced by using the experimental gear or 18/0 circle hook;(2)the depth,temperature,salinity,chlorophyll concentration and dissolved oxygen(DO)range with the high incidental catch rate for C.falciformis was 40.0-79.9 m,24.0-24.9 ℃ and 29.0-29.9 ℃,35.40-35.99,0.120-0.199 μg/L,and 4.50-4.99 mg/L,respectively.This study suggests that:(1)the numbers of 18/0 circle hook or hook deeper than 120 m should be increased;(2)the numbers of hook should be reduced in the higher incidental catch rate ranges of hook depth,temperature,salinity,dissolved oxygen concentration and chlorophyll concentration.