T his study compared and evaluated the efficiency of two otolith shape descriptors(i.e., the elliptic Fourier transform(EFT) and discrete wavelet transform(DWT)) and morphometrics for stock discrimination. To accompli...T his study compared and evaluated the efficiency of two otolith shape descriptors(i.e., the elliptic Fourier transform(EFT) and discrete wavelet transform(DWT)) and morphometrics for stock discrimination. To accomplish this, sample fish from three stocks of yellow croaker L arimichthys polyactis along the Chinese coast(LDB stock from the Liaodong Bay of the Bohai Sea, JZB stock from the Jiaozhou Bay of the Yellow Sea and CJE stock from the Changjiang River estuary of the East China Sea) were used for otolith morphology analyses. The results showed that morphometrics produced an overall classification success rate of 70.8% in contrast with success rates of 80.0% or 82.0% obtained using EFT or DWT, respectively. This suggests that the two shape descriptors comparably discriminated among the stocks and performed more efficiently than morphometrics. During data adjustment and acquisition, some size variables were excluded from the subsequent discriminant analysis for stock discrimination because they were statistically "inef fective," which could reduce the efficiency of morphometrics and lead to relatively low overall classification success. Both EFT and DWT retain the contour coefficients and thus provide a detailed description of otolith shape, which could improve discriminatory efficiency compared with morphometrics.展开更多
This study analyzed and compared variations of the sulcus and otolith outlines of three geographic stocks(Huanghe(Yellow)River estuary(HHE),Jiaozhou Bay(JZB),and Changjiang(Yangtze)River estuary(CJE))of white croaker ...This study analyzed and compared variations of the sulcus and otolith outlines of three geographic stocks(Huanghe(Yellow)River estuary(HHE),Jiaozhou Bay(JZB),and Changjiang(Yangtze)River estuary(CJE))of white croaker Pennahia argentata in northern Chinese coastal waters.The sulcus and otolith outline analyses via elliptical Fourier transform(EFT,i.e.,outline analysis)achieved an overall classifi cation rate of 80.4%and 87.2%,respectively.Based on a combination of sulcus and otolith shape indices(SIs)and two derivative ratios,a moderate discriminatory effi ciency of 64.7%was obtained.The results indicate that sulcus outline analysis could be used alone to discriminate white croaker stocks,and that both sulcus and otolith outline analyses discriminated the fi sh stocks at a higher classifi cation rate than the shape indices.The sulcus outline analysis provided complementary information to the whole otolith outline analysis for stock discrimination.Both the sulcus and otolith outline analyses effi ciently discriminated between the most geographically separated CJE and HHE stocks,indicating that they could be considered discrete stocks for fi shery management.展开更多
Removal of the length ef fect in otolith shape analysis for stock identification using length scaling is an important issue; however, few studies have attempted to investigate the ef fectiveness or weakness of this me...Removal of the length ef fect in otolith shape analysis for stock identification using length scaling is an important issue; however, few studies have attempted to investigate the ef fectiveness or weakness of this methodology in application. The aim of this study was to evaluate whether commonly used size scaling methods and normalized elliptic Fourier descriptors(NEFDs) could ef fectively remove the size ef fect of fish in stock discrimination. To achieve this goal, length groups from two known geographical stocks of yellow croaker, L arimichthys polyactis, along the Chinese coast(five groups from the Changjiang River estuary of the East China Sea and three groups from the Bohai Sea) were subjected to otolith shape analysis. The results indicated that the variation of otolith shape caused by intra-stock fish length might exceed that due to inter-stock geographical separation, even when otolith shape variables are standardized with length scaling methods. This variation could easily result in misleading stock discrimination through otolith shape analysis. Therefore, conclusions about fish stock structure should be carefully drawn from otolith shape analysis because the observed discrimination may primarily be due to length ef fects, rather than dif ferences among stocks. The application of multiple methods, such as otoliths shape analysis combined with elemental fingering, tagging or genetic analysis, is recommended for sock identification.展开更多
基金Supported by the National Key Basic Research Program of China(973 Program)(No.2015CB453302)the NSFC-Shandong Joint Fund for Marine Science Research Centre(No.U1606404)the Aoshan Science and Technology Innovation Project(No.2015ASKJ02-04)
文摘T his study compared and evaluated the efficiency of two otolith shape descriptors(i.e., the elliptic Fourier transform(EFT) and discrete wavelet transform(DWT)) and morphometrics for stock discrimination. To accomplish this, sample fish from three stocks of yellow croaker L arimichthys polyactis along the Chinese coast(LDB stock from the Liaodong Bay of the Bohai Sea, JZB stock from the Jiaozhou Bay of the Yellow Sea and CJE stock from the Changjiang River estuary of the East China Sea) were used for otolith morphology analyses. The results showed that morphometrics produced an overall classification success rate of 70.8% in contrast with success rates of 80.0% or 82.0% obtained using EFT or DWT, respectively. This suggests that the two shape descriptors comparably discriminated among the stocks and performed more efficiently than morphometrics. During data adjustment and acquisition, some size variables were excluded from the subsequent discriminant analysis for stock discrimination because they were statistically "inef fective," which could reduce the efficiency of morphometrics and lead to relatively low overall classification success. Both EFT and DWT retain the contour coefficients and thus provide a detailed description of otolith shape, which could improve discriminatory efficiency compared with morphometrics.
基金Supported by the National Natural Science Foundation of China(NSFC)under the Programs Science Fund for Creative Research Groups(Nos.40821004,41121064)。
文摘This study analyzed and compared variations of the sulcus and otolith outlines of three geographic stocks(Huanghe(Yellow)River estuary(HHE),Jiaozhou Bay(JZB),and Changjiang(Yangtze)River estuary(CJE))of white croaker Pennahia argentata in northern Chinese coastal waters.The sulcus and otolith outline analyses via elliptical Fourier transform(EFT,i.e.,outline analysis)achieved an overall classifi cation rate of 80.4%and 87.2%,respectively.Based on a combination of sulcus and otolith shape indices(SIs)and two derivative ratios,a moderate discriminatory effi ciency of 64.7%was obtained.The results indicate that sulcus outline analysis could be used alone to discriminate white croaker stocks,and that both sulcus and otolith outline analyses discriminated the fi sh stocks at a higher classifi cation rate than the shape indices.The sulcus outline analysis provided complementary information to the whole otolith outline analysis for stock discrimination.Both the sulcus and otolith outline analyses effi ciently discriminated between the most geographically separated CJE and HHE stocks,indicating that they could be considered discrete stocks for fi shery management.
基金Supported by the National Basic Research Program of China(973 Program)(No.2015CB453302)the NSFC-Shandong Joint Fund for Marine Science Research Centre(No.U1606404)the Aoshan Science and Technology Innovation Project(No.2015ASKJ02-04)
文摘Removal of the length ef fect in otolith shape analysis for stock identification using length scaling is an important issue; however, few studies have attempted to investigate the ef fectiveness or weakness of this methodology in application. The aim of this study was to evaluate whether commonly used size scaling methods and normalized elliptic Fourier descriptors(NEFDs) could ef fectively remove the size ef fect of fish in stock discrimination. To achieve this goal, length groups from two known geographical stocks of yellow croaker, L arimichthys polyactis, along the Chinese coast(five groups from the Changjiang River estuary of the East China Sea and three groups from the Bohai Sea) were subjected to otolith shape analysis. The results indicated that the variation of otolith shape caused by intra-stock fish length might exceed that due to inter-stock geographical separation, even when otolith shape variables are standardized with length scaling methods. This variation could easily result in misleading stock discrimination through otolith shape analysis. Therefore, conclusions about fish stock structure should be carefully drawn from otolith shape analysis because the observed discrimination may primarily be due to length ef fects, rather than dif ferences among stocks. The application of multiple methods, such as otoliths shape analysis combined with elemental fingering, tagging or genetic analysis, is recommended for sock identification.
