Application of Otolith Outline Analysis for Stock Differentiation of the Azov–Black Sea Anchovy Engraulis encrasicolus (Engraulidae)

Date

2026-08-01

Author

Chesalin, M.V.
Nikolsky, V.N.
Akkuş, Gizem
Gücü, Ali Cemal

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Abstract: The Black Sea anchovy Engraulis encrasicolus ponticus is the principal target species of commercial fisheries in Türkiye, whereas the Azov anchovy E. e. maeoticus represents an important fishery resource for the Russian Federation in the Azov and Black seas. Because the ranges of these subspecies (or populations) partially overlap, their misidentification and the resulting inaccuracies in catch statistics complicate fisheries management. To differentiate stocks of Azov and Black Sea anchovy, we applied an otolith shape analysis approach based on elliptic Fourier descriptors combined with multivariate statistical methods and analyzed otoliths from 1502 fish obtained from 18 samples collected during 2014–2020. Otoliths of juveniles less than 9 cm in total length differed significantly from those of adults, whereas no sexual dimorphism in otolith shape was detected among adult fish. Exploratory multivariate analyses, including principal component and cluster analyses, showed that all examined otoliths formed two distinct clusters corresponding to the Azov and Black Sea morphotypes. Otoliths of the Azov anchovy were characterized by greater dorsoventral width, whereas those of the Black Sea anchovy had a deeper excisura between the rostrum and antirostrum, as well as a more pronounced rostrum. Linear discriminant analysis based on Fourier shape descriptors correctly assigned 80% of otoliths to the two morphotypes. These results demonstrate that otolith shape analysis is an effective tool for differentiating stocks of Azov and Black Sea anchovy.

Subject Keywords

Azov anchovy, Black Sea, Black Sea anchovy, elliptic Fourier analysis, otolith, Sea of Azov, shape analysis, stock discrimination

URI

https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=105048218708&origin=inward
https://hdl.handle.net/11511/120832

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Graduate School of Marine Sciences, Article