长江口日本鳗鲡降海产卵洄游群体的银化指标研究
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摘要
以长江口降海生殖洄游途中的日本鳗鲡为研究材料,对繁殖群体银化过程中体色、年龄、全长、体重及银化指标等特征作了分析。结果显示,依据"体侧黑色素沉积是否蔓延至胸鳍下缘"这一体色标准,可将日本鳗鲡洄游群体分为银化前期和银化期二个发育期。日本鳗鲡银化过程中,体型、胸鳍长、眼径、性腺指数呈递增趋势,消化道指数则呈递减趋势。主成分分析亦表明,银化期较银化前期的眼径和胸鳍增大,还具有较高的性腺指数和较低的消化道饱满度。由于日本鳗鲡的产卵场位于3000 km之遥的马里亚纳海沟,这些形态的修正可能是为了适应即将起始的长距离降海生殖洄游。根据银化指标所建立的判别方程,对雌、雄群体银化前期和银化期的判别分析均取得了95%以上的成功率。研究认为,长江口日本鳗鲡银化期的野外快速判别,亦可采用"眼径指数大于5"作为识别依据。
To establish a simple and reliable index for determining silvering stages of the Japanese eel, Anguilla japonica, we observed the colorations of various body parts and biological characteristics on the reproductive stock of the eels from the Yangtze River estuary before starting their oceanic migrations. The body color, and age, total length, body weight, and silvering index were analyzed in the silvering process of the Japanese eel. The two silvering stages are characterized by the colorations of trunk skin as follows:(1) Pre-silver stage: pigments deposited completely on the upper edge of pectoral fin on the lateral sides of trunk,(2) Silver stage: pigments deposited completely on the lower edge of pectoral fin on the lateral sides of trunk.The body size, eye diameter, pectoral fins length and gonad-somatic index were increased from pre-silver stage to silver stage, and digestive tract index were decreased in contrast. The principal component analysis demonstrated that the silver stage eels had larger eye and pectoralfins, higher sexual maturity and the degenerated digestive tract compared to pre-silver stage eels. Without feeding, the various modifications of the body and physiological changes indicated that silver eels developed various adaptations to prepare the long oceanic migration. The silver stage and pre-silver stage could be distinguished by canonical discriminant function analysis using five characters with a 95% reliability for correct classification. Our results revealed that an eye index of 5.0 is the cut off point for distinguishing the silver stage from the pre-silver stage of the Japanese eels for the field survey.
To establish a simple and reliable index for determining silvering stages of the Japanese eel, Anguilla japonica, we observed the colorations of various body parts and biological characteristics on the reproductive stock of the eels from the Yangtze River estuary before starting their oceanic migrations. The body color, and age, total length, body weight, and silvering index were analyzed in the silvering process of the Japanese eel. The two silvering stages are characterized by the colorations of trunk skin as follows:(1) Pre-silver stage: pigments deposited completely on the upper edge of pectoral fin on the lateral sides of trunk,(2) Silver stage: pigments deposited completely on the lower edge of pectoral fin on the lateral sides of trunk.The body size, eye diameter, pectoral fins length and gonad-somatic index were increased from pre-silver stage to silver stage, and digestive tract index were decreased in contrast. The principal component analysis demonstrated that the silver stage eels had larger eye and pectoralfins, higher sexual maturity and the degenerated digestive tract compared to pre-silver stage eels. Without feeding, the various modifications of the body and physiological changes indicated that silver eels developed various adaptations to prepare the long oceanic migration. The silver stage and pre-silver stage could be distinguished by canonical discriminant function analysis using five characters with a 95% reliability for correct classification. Our results revealed that an eye index of 5.0 is the cut off point for distinguishing the silver stage from the pre-silver stage of the Japanese eels for the field survey.
引文
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[19]Li C Y,Huang B,Xiong J,et al.Molecular cloning and characterization of TLR21 gene from Japanese eel,Anguilla japonica[J].Acta Hydrobiologica Sinica,2017,41(2):296-305[李春艳,黄贝,熊静,等.日本鳗鲡TLR21基因的鉴定、免疫应答与启动子分析.水生生物学报,2017,41(2):296-305]
[20]Guo H Y,Zheng Y,Tang W Q,et al.Behavioral migration diversity of the Yangtze River Japanese Eel,Anguilla japonica,based on otolith Sr/Ca ratios[J].Zoological Research,2011,32(4):442-450
[21]Guo H Y,Wei K,Tang W Q,et al.Developmental stages and migratory routes of larvae Japanese eel from southeast coastal estuaries of China[J].Journal of Fisheries of China,2012,36(12):1793-1801[郭弘艺,魏凯,唐文乔,等.中国东南沿海日本鳗鲡幼体的发育时相及其迁徙路径分析.水产学报,2012,36(12):1793-1801]
[22]Wang D H,Gong X L,Bao B L,et al.The growth characteristics of catadromous Japanese eels(Anguilla japonica)from the Yangtze River Estuary,China[J].Journal of Shanghai Ocean University,2016,25(1):25-33[汪德海,龚小玲,鲍宝龙,等.长江口降海洄游日本鳗鲡的生长特性.上海海洋大学学报,2016,25(1):25-33]
[23]Guo H Y,Zhang Y,Tang W Q.Pigmentation stages and body proportions of Anguilla japonica glass eels at the Yangtze River Estuary[J].Acta Hydrobiologica Sinica,2015,39(1):197-202[郭弘艺,张亚,唐文乔,等.长江口日本鳗鲡幼体色素发育时相及其体型变化.水生生物学报,2015,39(1):197-202]
[24]Hu W D.Research on early life history of Anguilla japonica temmink et schlegel recruitment in Yangtze Estuary[D].Shanghai Ocean University.2012[胡达吾.长江口日本鳗鲡(Anguilla Japonica Temminck et Schlegel)补充群体早期生活史研究.上海海洋大学.2012]
[25]Han Y S,Tzeng W N,Liao I C.Gonadotropin inducedsynchronous changes of morphology and gonadal development in the Japanese eel Anguilla japonica[J].Journal of Fisheries Society of Taiwan,2007,33(4):333-343
[26]Lin D,Lin H R,Huang Y H,et al.Studies on the breeding biology of the eel(Anguilla japonica Temminck Schlegel)[J].Acta Hydrobiologica Sinica,1977,1(2):177-190[林鼎,林浩然,黄奕华,等.鳗鲡繁殖生物学研究--Ⅰ.下海鳗鲡雌雄性状差异和鉴别.水生生物学报,1977,1(2):177-190]
[27]Pankhurst N.Relation of visual changes to the onset of sexual maturation in the European eel Anguilla anguilla(L.)[J].Journal of Fish Biology,1982,21(2):127-140
[28]Xie Z L,Guo H Y,Tang W Q,et al.Age structure and growth characteristics at seaward migrating periods of Anguilla japonica in the Yangtze River Estuary[J].Journal of Fisheries of China,2010,34(2):245-254[谢正丽,郭弘艺,唐文乔,等.长江口降海洄游鳗鲡的年龄结构与生长特征.水产学报,2010,34(2):245-254]
[29]Acou A,Boury P,Laffaille P,et al.Towards a standardized characterization of the potentially migrating silver European eel(Anguilla anguilla,L.)[J].Archiv für Hydrobiologie,2005,164(2):237-255
[30]Pankhurst N,Lythgoe J.Structure and colour of the integument of the European eel Anguilla anguilla(L.)[J].Journal of Fish Biology,1982,21(3):279-296
[31]Lokman P M,Vermeulen G J,Lambert J G,et al.Gonad histology and plasma steroid profiles in wild New Zealand freshwater eels(Anguilla dieffenbachii and A.australis)before and at the onset of the natural spawning migration.I.Females[J].Fish Physiology and Biochemistry,1998,19(4):325-338
[32]Cottrill R D,McKinley R S,Kraak G D.An examination of utilizing external measures to identify sexually maturing female American eels,Anguilla rostrata,in the St.Lawrence River[J].Environmental Biology of Fishes,2002,65:271-287
[33]Tsukamoto K,Chow S,Otake T,et al.Oceanic spawning ecology of freshwater eels in the western North Pacific[J].Nature communications,2011,1174(2):179-187
[34]Davey A,Jellyman D.Sex determination in freshwater eels and management options for manipulation of sex[J].Reviews in Fish Biology and Fisheries,2005,15:37-52
[2]Tsukamoto K.Oceanic migration and spawning of anguillid eels[J].Journal of Fish Biology,2009,74(9):1833-1852
[3]Tesch F W.The Eel:Biology and Management of Anguillid Eels[M].London:Chapman and Hall.2008,9-78
[4]Tzeng W,Lin H,Wang C,et al.Differences in size and growth rates of male and female migrating Japanese eels in Pearl River,China[J].Journal of Fish Biology,2000,57(5):1245-1253
[5]Durif C,Dufour S,Elie P.The silvering process of Anguilla anguilla:a new classification from the yellow resident to the silver migrating stage[J].Journal of FishBiology,2005,66(4):1025-1043
[6]Tanaka,H.Progression in artificial seedling production of Japanese eel Anguilla japonica[J].Fisheries Science,2015,81(1):11-19
[7]Okamura A,Yamada Y,Yokouchi K,et al.A silvering index for the Japanese eel Anguilla japonica[J].Environmental Biology of Fishes,2007,80(1):77-89
[8]Han Y S,Liao I C,Huang Y S,et al.Synchronous changes of morphology and gonadal development of silvering Japanese eel Anguilla japonica[J].Aquaculture,2003,219(1):783-796
[9]Han Y S,Tzeng W N,Huang Y S,et al.Silvering in the eel:changes in morphology,body fat content,and gonadal development[J].Journal of Taiwan Fisheries Research,2001,9(1):119-127
[10]Han Y,Tzeng W,Huang Y,et al.The silvering of the Japanese eel Anguilla japonica:season,age,size and fat[J].Journal of Taiwan Fisheries Research,2000,8(1):37-45
[11]Ijiri S,Kayaba T,Takeda N,et al.Pretreatment reproductive stage and oocyte development induced by salmon pituitary homogenate in the Japanese eel Anguilla japonica[J].Fisheries Science,1998,64(4):531-537
[12]Liao I,Chang S.Induced spawning and larval rearing of Japanese eel,Anguilla japonica in Taiwan[J].Journal of Taiwan Fisheries Research,2001,9(1):97-108
[13]Tsukamoto K,Kuroki M.Eels and Humans[M].Springer.2014,117-128
[14]Liu K,Duan J R,Xu D P,et al.Studies on distribution characteristics and catching indexes fluctuation in fishing season of elvers of Japanese eel in the Yangtze River Estuary[J].Journal of Shanghai Ocean University,2010,19(6):814-821[刘凯,段金荣,徐东坡,等.长江口日本鳗鲡苗汛特征及捕捞量时空变动.上海海洋大学学报,2010,19(6):814-821]
[15]Shuai F M,Li Z Q,Liu G W,et al.Resource status of Japanese eel(Anguilla japonica)in the Pearl River Estuary[J].South China Fisheries Science,2015,11(02):85-89[帅方敏,李智泉,刘国文,等.珠江口日本鳗鲡种苗资源状况研究.南方水产科学,2015,11(02):85-89]
[16]Guo H,Zhang X,Zhang Y,et al.Effects of environmental variables on recruitment of Anguilla japonica glass eels in the Yangtze Estuary,China[J].Fisheries Science,2017,83(3):333-341
[17]Zhang X,Xu P,Xu G P,et al.Analysis of Genetic Structure of China East Sea Anguilla japonica by AFLP[J].Chinese Journal of Ecology,2010,(1):82-86[张辛,许璞,许广平,等.中国东海日本鳗鲡种群遗传结构的AFLP分析.水生态学杂志,2010,(1):82-86]
[18]Peng X X,Huang B,Duan L P,et al.Characterization,expression pattern and promoter activity analysis of interferon-gamma in Japanese eel,Anguilla japonica[J].Acta Hydrobiologica Sinica,2017,41(3):589-602[彭喜霞,黄贝,段利朋,等.日本鳗鲡IFN-γ基因的鉴定、表达模式及启动子活性分析.水生生物学报,2017,41(3):589-602]
[19]Li C Y,Huang B,Xiong J,et al.Molecular cloning and characterization of TLR21 gene from Japanese eel,Anguilla japonica[J].Acta Hydrobiologica Sinica,2017,41(2):296-305[李春艳,黄贝,熊静,等.日本鳗鲡TLR21基因的鉴定、免疫应答与启动子分析.水生生物学报,2017,41(2):296-305]
[20]Guo H Y,Zheng Y,Tang W Q,et al.Behavioral migration diversity of the Yangtze River Japanese Eel,Anguilla japonica,based on otolith Sr/Ca ratios[J].Zoological Research,2011,32(4):442-450
[21]Guo H Y,Wei K,Tang W Q,et al.Developmental stages and migratory routes of larvae Japanese eel from southeast coastal estuaries of China[J].Journal of Fisheries of China,2012,36(12):1793-1801[郭弘艺,魏凯,唐文乔,等.中国东南沿海日本鳗鲡幼体的发育时相及其迁徙路径分析.水产学报,2012,36(12):1793-1801]
[22]Wang D H,Gong X L,Bao B L,et al.The growth characteristics of catadromous Japanese eels(Anguilla japonica)from the Yangtze River Estuary,China[J].Journal of Shanghai Ocean University,2016,25(1):25-33[汪德海,龚小玲,鲍宝龙,等.长江口降海洄游日本鳗鲡的生长特性.上海海洋大学学报,2016,25(1):25-33]
[23]Guo H Y,Zhang Y,Tang W Q.Pigmentation stages and body proportions of Anguilla japonica glass eels at the Yangtze River Estuary[J].Acta Hydrobiologica Sinica,2015,39(1):197-202[郭弘艺,张亚,唐文乔,等.长江口日本鳗鲡幼体色素发育时相及其体型变化.水生生物学报,2015,39(1):197-202]
[24]Hu W D.Research on early life history of Anguilla japonica temmink et schlegel recruitment in Yangtze Estuary[D].Shanghai Ocean University.2012[胡达吾.长江口日本鳗鲡(Anguilla Japonica Temminck et Schlegel)补充群体早期生活史研究.上海海洋大学.2012]
[25]Han Y S,Tzeng W N,Liao I C.Gonadotropin inducedsynchronous changes of morphology and gonadal development in the Japanese eel Anguilla japonica[J].Journal of Fisheries Society of Taiwan,2007,33(4):333-343
[26]Lin D,Lin H R,Huang Y H,et al.Studies on the breeding biology of the eel(Anguilla japonica Temminck Schlegel)[J].Acta Hydrobiologica Sinica,1977,1(2):177-190[林鼎,林浩然,黄奕华,等.鳗鲡繁殖生物学研究--Ⅰ.下海鳗鲡雌雄性状差异和鉴别.水生生物学报,1977,1(2):177-190]
[27]Pankhurst N.Relation of visual changes to the onset of sexual maturation in the European eel Anguilla anguilla(L.)[J].Journal of Fish Biology,1982,21(2):127-140
[28]Xie Z L,Guo H Y,Tang W Q,et al.Age structure and growth characteristics at seaward migrating periods of Anguilla japonica in the Yangtze River Estuary[J].Journal of Fisheries of China,2010,34(2):245-254[谢正丽,郭弘艺,唐文乔,等.长江口降海洄游鳗鲡的年龄结构与生长特征.水产学报,2010,34(2):245-254]
[29]Acou A,Boury P,Laffaille P,et al.Towards a standardized characterization of the potentially migrating silver European eel(Anguilla anguilla,L.)[J].Archiv für Hydrobiologie,2005,164(2):237-255
[30]Pankhurst N,Lythgoe J.Structure and colour of the integument of the European eel Anguilla anguilla(L.)[J].Journal of Fish Biology,1982,21(3):279-296
[31]Lokman P M,Vermeulen G J,Lambert J G,et al.Gonad histology and plasma steroid profiles in wild New Zealand freshwater eels(Anguilla dieffenbachii and A.australis)before and at the onset of the natural spawning migration.I.Females[J].Fish Physiology and Biochemistry,1998,19(4):325-338
[32]Cottrill R D,McKinley R S,Kraak G D.An examination of utilizing external measures to identify sexually maturing female American eels,Anguilla rostrata,in the St.Lawrence River[J].Environmental Biology of Fishes,2002,65:271-287
[33]Tsukamoto K,Chow S,Otake T,et al.Oceanic spawning ecology of freshwater eels in the western North Pacific[J].Nature communications,2011,1174(2):179-187
[34]Davey A,Jellyman D.Sex determination in freshwater eels and management options for manipulation of sex[J].Reviews in Fish Biology and Fisheries,2005,15:37-52