Application of otolith shape analysis for stock discrimination and species identification of five goby species （Perciformes： Gobiidae） in the northern Chinese coastal waters

We tested the use of otolith shape analysis to discriminate between species and stocks of five goby species( Ctenotrypauchen chinensis, Odontamblyopus lacepedii, Amblychaeturichthys hexanema, Chaeturichthys stigmatias, and Acanthogobius hasta) found in northern Chinese coastal waters. The five species were well differentiated with high overall classification success using shape indices(83.7%), elliptic Fourier coefficients(98.6%), or the combination of both methods(94.9%). However, shape analysis alone was only moderately successful at discriminating among the four stocks(Liaodong Bay, LD; Bohai Bay, BH; Huanghe(Yellow) River estuary HRE, and Jiaozhou Bay, JZ stocks) of A. hasta(50%–54%) and C. stigmatias(65.7%–75.8%). For these two species, shape analysis was moderately successful at discriminating the HRE or JZ stocks from other stocks, but failed to effectively identify the LD and BH stocks. A large number of otoliths were misclassified between the HRE and JZ stocks, which are geographically well separated. The classification success for stock discrimination was higher using elliptic Fourier coefficients alone(70.2%) or in combination with shape indices(75.8%) than using only shape indices(65.7%) in C. stigmatias whereas there was little difference among the three methods for A. hasta. Our results supported the common belief that otolith shape analysis is generally more effective for interspecific identification than intraspecific discrimination. Moreover, compared with shape indices analysis, Fourier analysis improves classification success during inter- and intra-species discrimination by otolith shape analysis, although this did not necessarily always occur in all fish species.     

Otolith shape analysis for stock discrimination of two Collichthys genus croaker(Pieces: Sciaenidae,) from the northern Chinese coast

The otolith morphology of two croaker species(C ollichthys lucidus and C ollichthys niveatus) from three areas(Liaodong Bay, LD; Huanghe(Yellow) River estuary, HRE; Jiaozhou Bay, JZ) along the northern Chinese coast were investigated for species identifi cation and stock discrimination. The otolith contour shape described by elliptic Fourier coefficients(EFC) were analysed using principal components analysis(PCA) and stepwise canonical discriminant analysis(CDA) to identify species and stocks. The two species were well dif ferentiated, with an overall classifi cation success rate of 97.8%. And variations in the otolith shapes were significant enough to discriminate among the three geographical samples of C. lucidus(67.7%) or C. niveatus(65.2%). Relatively high mis-assignment occurred between the geographically adjacent LD and HRE samples, which implied that individual mixing may exist between the two samples. This study yielded information complementary to that derived from genetic studies and provided information for assessing the stock structure of C. lucidus and C. niveatus in the Bohai Sea and the Yellow Sea.     

Comparative study of otolith and sulcus morphology for stock discrimination of yellow drum along the Chinese coast

Otolith morphology is widely used for fish stock identification.The sulcus,a structure on the medial side of the otolith,is an important feature in morphological analysis.This study was conducted to evaluate the feasibility of using sulcus morphology for stock identification and to compare its performance with commonly used otolith morphology analysis.Otoliths were collected and analyzed from three geographical groups(the Huanghe(Yellow)River estuary,HHE;the Jiaozhou Bay,JZB;and the Changjiang(Yangtze)River estuary,CJE)of yellow drum Nibea albiftora.The results show that the analysis of sulcus morphology based on shape indices(SIs),elliptic Fourier coefficients(EFc),and a combination of the two parameters identified stocks at overall classification rates of 51.0%,72.5%,and 73.2%,respectively.These classification rates are similar to those obtained using otolith morphology analysis(57.0%,73.8%,and76.5%by SIs,EFc,and their combination,respectively).The findings suggest that sulcus morphology is comparable to the commonly used otolith morphology for identifying stocks of sciaenids,such as the yellow drum.For both otolith and sulcus morphology,EFc could identify the stocks more efficiently than SIs,while the combination of SIs and EFc was even better.     

Analyses of egg size,otolith shape,and growth revealed two components of small yellow croaker in Haizhou Bay spawning stock

The geographic al variations in life history characteristic s of small yellow cro aker Larimich thys polyactis,caused by experienced different environmental conditions,have been observed in China seas.Previous studies based on spatial distribution,migration route,and body morphometrics suggested a complex stock structure.In this study,to clarify the source of a spawning stock,we investigated the reproduction strategy and inter-structure of the Haizhou Bay(HZB)spawning stock in the middle Yellow Sea from both egg survey and adult otolith increment analysis.Egg and adult samples were collected from three surveys during spawning season in 2013.Distinct spatial and temporal variations were detected in egg distribution and size,and otolith shape analy sis of adult fishes revealed two morphotypes with different increment growth using random forest cluster.The results indicate the existence of two components within the same spawning stock in HZB from different wintering grounds,and accordingly special protection should be required for this stock given the significance to maintain connectivity between adj acent subpopulations.     

Stock discrimination of spottedtail goby (Synechogobius ommaturus) in the Yellow Sea by analysis of otolith shape

Otolith shape is species specific and is an ideal marker of fish population affiliation. In this study, otolith shape of spottedtail goby Synechogobius ommaturus is used to identify stocks in different spawning locations in the Yellow Sea. The main objectives of this study are to explore the potential existence of local stocks of spottedtail goby in the Yellow Sea by analysis of otolith shape, and to investigate ambient impacts on otolith shape. Spottedtail goby was sampled in five locations in the Yellow Sea in 2007 and 2008. Otoliths are described using variables correlated to size (otolith area, perimeter, length, width, and weight) and shape (rectangularity, circularity, and 20 Fourier harmonics). Only standardized otolith variables are used so that the effect of otolith size on the shape variables could be eliminated. There is no significant difference among variables of sex, year, and side (left and right). However, the otolith shapes of the spring stocks and the autumn stocks differ significantly. Otolith shape differences are greater among locations than between years. Correct classification rate of spottedtail goby with the otolith shape at different sampling locations range from 29.7%–77.4%.     

Otolith chemical signatures of spottedtail goby Synechogobius ommaturus in coastal waters of China

This study explores the potential existence of local stocks of Synechogobius ommaturus using otolith chemical signatures. The concentrations of 10 elements (K, Ca, Na, Mg, Sr, Pb, Ba, Mn, Co, Zn) in the otoliths from eight stocks (Dandong, Dalian, Tianjin, Dongying, Weihai, Qingdao, Ganyu and Xiamen) of S. ommaturus were measured by Inductively Coupled Plasma Mass Spectrometry and regressed against otolith weight. No significant correlation between otolith weight and concentrations of Na, Mg, Ca, Sr, Co, Ba, Zn and Pb were observed. Concentrations of K and Mn were correlated with otolith weight. Consequently, the residuals of the regressions were used instead of the original concentrations in subsequent analyses. Analysis of variance (ANOVA) showed no significant difference between males and females in otolith chemical signatures. Differences were found among the locations for K, Sr, Mn, Co, Ba, Pb, but not for Ca, Na, Mg and Zn. Residuals of the regressions of elemental concentrations against otolith weight that fitted the normal distribution and homogeneity were studied by discriminant analysis. The success of the discriminant function to predict the location of S. ommaturus capture ranged from 100% for Weihai and Xiamen stocks, to only 44.4% and 62.5% for Qingdao and Dandong stocks, respectively. The average prediction success was 80.3%.     

Genetic variation in two sea cucumber （Apostichopus japonicus） stocks revealed by ISSR markers

Sea cucumber Apostichopus japonicus samples were collected in Changdao, Penglai (PL), 27 individuals, and Lingshandao, Qingdao (QD), 30 individuals, in the Shandong Peninsula, China. Ten SSR primers were used to assess the genetic variation and relationship between and within the two stocks. Respectively, for each stock, the percentage of polymorphic bands was 85.2% and 86.9%; the gene diver- sity was 0.360 5 and 0.342 8; and the Shannon’s information index was 0.515 0 and 0.499 0. At species level, the percentage of polymorphic bands was 92.2%, the total gene diversity was 0.378 9 and the Shannon’s information index was 0.550 4. The coefficient of overall genetic differentiation and the ge- netic distances between the stocks were also calculated to be 0.073 0 and 0.079 6 using the POPGENE program. Results show that the genetic diversity of the two stocks is still large but the genetic distance between the two stocks is close. A dendrogram was constructed for the 57 individuals from the two stocks, showing that the genetic structure was unitary for PL stock but complex for QD stock.     

Fluorescence discrimination and determination technique for phytoplankton composition by Coif2 wavelet packet

An in vivo fluorescence discrimination technique for phytoplankton population was developed by using Wavelet packet transform, cluster analysis and non-negative least squares. The technique was used to analyze water samples from different sea regions. For simulative mixtures, when dominant species account for 60%, 70%, 80%, 90% at the division level, the correct discrimination ratios (CDRs) are 83.0%, 99.1%, 99.7% and 99.9% with the relative contents of 58.5%, 68.4%, 77.7% and 86.3%, respectively; when the algae dominance are 60%, 70%, 80%, 90%, 100% at the genus level, the CDRs are 86.1%, 94.9%, 95.2%, 96.8% and 96.7%, respectively. For laboratory mixtures, the CDRs are 88.1% and 78.4% at the division and genus level, respectively. For field samples, the CDRs were 91.7% and 80% at the division and genus level, respectively (mesocosm experiments), and the CDRs were 100% and 66.7% at the division and genus level, respectively (Jiaozhou Bay). The fluorometric technique was used to estimate the phytoplankton community composition and relative abundance of different classes for the April 2010 cruise in the Yellow Sea with the results agreeing with those in published papers by other authors.     

2015—2020年辽东湾海冰冰情时空特征及其影响因素

受冬季强寒潮侵袭,辽东湾会出现大范围结冰现象。为了分析2015—2020年辽东湾海冰冰情的变化规律与影响因素,本文选取Sentinel-1A/B数据开展辽东湾海冰监测。首先,采用巴氏距离选择最优纹理特征组合,再利用最大似然方法实现海冰分类;然后,根据上述海冰分类结果,分析海冰冰情等级、海冰外缘线、海冰面积、海冰类型和海冰结冰概率等冰情特征的变化规律;最后,研究海水深度、海温、气温和风速与海冰冰情的关系。主要结论如下：① 采用不同纹理特征组合方法和本文方法对2020年2月1日Sentinel-1B影像进行实验,结果表明本文方法的总体分类精度和Kappa系数分别为93.16%和0.85,分类精度最高。② 11月末到12月海冰类型以初生冰为主,间有灰冰;1月到2月中上旬以灰冰为主,间有初生冰和白冰;2月下旬到3月上旬的海冰类型以灰冰和初生冰为主。辽东湾内部结冰概率存在差异,北部沿岸结冰概率高于南部,东部结冰概率高于西部。辽东湾海冰冰情受海水深度、海温和气温影响明显,受风速影响较小。     

Use of Otolith Shape for the Identification of Trumpeter Sillago （Sillago maculata） and Silver Sillago （Sillago sihama）

Otolith shape is species-specific in fish. In this study, 161 samples of Trumpeter sillago Sillago maculata and 164 of Silver sillago Sillago sihama were collected from Beibu Gulf in July 2009. The main objective of this study was to use morphological variables and Fourier harmonics to describe otolith characteristics and use discriminant analyses to separate the two species. Otoliths were measured by traditional one and two dimensional measures(otolith length, width, diameters, area, perimeter, rectangularity and circularity), as well as by Fourier analysis to capture the finer regions of the otolith. Analysis of covariance(ANCOVA)showed that there was significant correlation between morphological variables(diameter, perimeter, otolith length, otolith width, otolith area, density, harmonics 3, harmonics 4, harmonics 5, harmonics 13, harmonics 15, and harmonics 16)and body length. To minimize size effects on the morphological variables between species, only fish with a body length between 90 and 140 mm were included in the data analysis and the variables which had significant relation with body length were transformed using the residual. The result showed that the accuracy of discriminant analysis was 97. 8% and 100% for Trumpeter sillago and Silver sillago, respectively. This high accuracy indicated that otolith shape was described accurately by morphological variables and Fourier harmonics, and discriminant analysis was an effective way to identify and separate the two species.     

Estimates of autumntime benthic secondary production in Laizhou Bay and adjacent Bohai Sea waters

The whole metazoan community inhabiting Laizhou Bay and adjacent Bohai Sea waters were sampled in late autumn,2006.Secondary production estimates for macrofauna and meiofauna were made separately.Total benthic secondary production was as high as 8.38 ± 4.08 g ash-free dry weight(AFDW) m-2 a-1,which represented the autumn production level.In general,macrofaunal secondary production in Laizhou Bay was much lower than that in adjacent Bohai Sea areas.In contrast,meiofaunal secondary production in Laizhou Bay was higher than that in adjacent Bohai Sea areas.Macrofauna contributed 61% to benthic secondary production(5.09 ± 3.26 g AFDW m-2 a-1),lower than the value in previous studies in Bohai Sea.Sediment granulometric characteristics and bottom-water salinity could explain the substantial variability in the macrofauna biomass and production.Meiofaunal production was an important component of benthic production and exceeded macrofauna production under exceptional conditions,e.g.in Laizhou Bay,where macrofauna was restricted.Chlorophyll pigments(Chl-a) concentrations in sediment explained the general meiofaunal biomass and production distribution here.     

Distribution and migration of the common squidTodarodes pacificus in the Yellow Sea

Study of the distribution and migration of the common squid,Todarodes pacificus Steenstrup,basedon the index of important fishing ground(P) and fisheries statistics on the Yellow Sea and northern EastChina Sea during 1980—1991 showed that:1.Its catch in the fishing period(June to November) is 91.77% of the annual yield.The fishingground distributes over the northem and middle Yel1ow Sea and adjacent area of the Changjiang Estuary.2. It over-winters in the northem East China Sea and waters adjacent to Goto Island from De-cember to February and spawns in waters near Haijiao Is1and and west of Kyushu. The main stock mi-grates along 123°30′E to the ChangJiang Estuary, Haizhou Bay. offsea from Shidao to Qingdao,mideastern Yellow Sea, and offsea Weihai and Haiyang Island succesively for feeding after April. The sur-plus stock migrates again to the wintering ground in December.3.The favorable feeding temperature is 6-23℃(optimum of l3-20℃ in the Changjiang Estua-ry and 7-13℃ in the northern and middle Yel     

Natural mortality estimation and rational exploitation of purpleback flying squid Sthenoteuthis oualaniensis in the southern South China Sea

Based on the biological data of purpleback flying squid(Sthenoteuthis oualaniensis)collected by light falling-net in the southern South China Sea(SCS) during September to October 2012 and March to April 2013,growth and mortality of 'Medium' and 'Dwarf' forms of squid are derived using the Powell-Wetherall,ELEFAN methods and length-converted catch curves(FiSAT package).Given a lack of commercial exploitation,we assume total mortality to be due entirely to natural mortality.We estimate these squid have fast growth,with growth coefficients(k) ranging from 1.42 to 2.39,and high natural mortality(M),with estimates ranging from 1.61 to 2.92.To sustainably exploit these squid stocks,yield per recruitment based on growth and natural mortality was determined using the Beverton-Holt dynamic pool model.We demonstrate squid stocks could sustain high fishing mortality and low ages at first capture,with an optimal fishing mortality 3.0,with the optimal age at first capture increased to 0.4-0.6 years when fishing mortality approached optimal levels.On the basis of our analyses and estimates of stock biomass,we believe considerable potential exists to expand the squid fishery into the open SCS,relieving fishing pressure on coastal waters.     

Otolith Microstructure Analysis Reveals Different Growth Histories of Japanese Sardine (Sardinops melanostictus) in the Oyashio Waters

After decades of low year classes,the stock of Japanese sardine(Sardinops melanostictus)has begun to recover since the mid-2000s.The hatch dates and otolith growth rates of age-0 juvenile sardine,which were collected in the subarctic Oyashio waters in autumn 2018,were determined from an otolith microstructure analysis.The sardines were hatched from late January to late April,while mostly in February and March.The otolith growth rate increased continuously up to 60 d after hatching and thereafter de-creased.The revealed growth rate in a crucial growth period is faster than that reported for juvenile sardines collected in the 1990s,which is coincided with the recent recovery trend of the sardine stock.Two groups with different hatch dates,growth histories,and migration routes were identified using unsupervised random forest clustering analysis.They were considered inshore and offshore migration individuals in accordance with recent researches.In the offshore group,a high proportion of sardine juveniles hatched late and grew faster in the Kuroshio-Oyashio transitional waters,a finding consistent with the hypothesis of growth-rate-dependent re-cruitment.This finding on the population composition and growth rate of juvenile sardine in the Oyashio waters can be a basis for an improved prediction of their survival and provides us with valuable information on the recruitment processes of this stock during the period of stock recovery.     

南海北部花斑蛇鲻生长死亡参数估计及开捕规格

将南海北部花斑蛇鲻分成南海北部大陆架和北部湾两个不同海域群体 ,计算花斑蛇鲻的生长与死亡参数。得到的VonBertalanffy生长方程的相关参数为 :南海北部大陆架L∞ =4 5.5cm ,K =0 .2 8,t0 =- 0 .4 6 0 ;北部湾L∞ =4 0 .0cm ,K =0 .30 ,t0 =- 0 .4 43。计算自然死亡系数得南海北部大陆架为 0 .6 3;北部湾为 0 .6 7;捕捞死亡系数南海北部大陆架为 0 .79,北部湾为 1.11。据等渔获量曲线建议南海北部大陆架花斑蛇鲻开捕体长由 13.3cm增加至 2 0 .0cm ,同时 ,捕捞死亡系数可由当前的 0 .79放宽至 1.0 ;北部湾花斑蛇鲻开捕体长由 13.5cm增加至 19.0cm的同时 ,捕捞死亡系数可由当前的 1.11放宽至 1.5。     

Biogenic silicate accumulation in sediments, Jiaozhou Bay

1 INTRODUCTION Silicate, or silicic acid (H4SiO4), is a very im- portant nutrient in the ocean. Unlike other major nu- trients such as phosphate and nitrate or ammonium, which are needed by almost all marine plankton, silicate is an essential chemical req…     

华贵栉孔扇贝两种壳色群体生长和消化酶活力比较

以华贵栉孔扇贝桔黄和紫褐壳色个体为亲本建立两个壳色群体,从壳长、壳高、壳宽和体重几方面进行生长比较,并对两个群体做了淀粉酶和纤维素酶活力比较。结果表明:桔黄壳色群体的平均壳长、平均壳高、平均壳宽和平均体重显著大于紫褐壳色群体(P<0.05)。在24℃、27℃、30℃和33℃条件下,桔黄壳色群体的淀粉酶和纤维素酶活力显著高于紫褐壳色群体(P<0.05);不同壳色群体生长与其淀粉酶和纤维素酶活力有关。     

Population identification of red-fin pargo,Parargyrops edita Tanaka,in Taiwan strait and Beibu Gulf

This paper deals with population identification ofParargyrops edita Tanaka. Samples of spawning stocks were collected from Niushan-Penghu, Minnan-Taiwan shoal (Southern Fujian-Taiwan shoal) and Beibu Gulf during the spawning period 1981–1982. Morphological characters, both meristic and morphometric, are counted and measured respectively. The stock concept and intraspecific categories have been discussed. Some meristic characters as the number of left or right ventral fin spine, right ventral fin rays and abdominal vertebrae of this fish may be constant, others as the numbers of left or right pectoral fin rays and gill-rakers may have obvious geographical variation. Morphological characters have not attained the level of subspecific distinctness, no sub-species could be found among these stocks by means of coefficient of difference (C.D.). Basing upon the comparative analysis ofM _diff, the authors consider that stocks of Minnan-Taiwan shoal and Niushan-Penghu belong to the same local population, Taiwan Strait local population. By means of the discriminant function analysis and linear relationship analysis, statistical differences will be found to exist in meristic characters between the stock of Minnan-Taiwan shoal and that of Niushan-Penghu, so that the two are virtually different stocks or subpopulations. The stock of Beibu Gulf belongs to another called the Beibu Gulf local population. These two local populations are of allopatric distribution and show statistically significant difference between themselves. Among these stocks, the Minnan-Taiwan shoal stock is strongly influenced by the much more complicated environmental conditions of the mixed boundary region of the subtropical Sino-Japanese Subregion in the north and the tropical Indo-Malayan Subregion in the south. Thus its coefficient of variability (C.V.) is greater than those of the other two in the mean values of various meristic characters. This paper was published in Chinese inOceanologia et Limnologia Sinica 14 (6): 511–520.