Metazoan parasites as biological tags for stock discrimination of whitemouth croaker Micropogonias furnieri.

Examination of 248 adult specimens of whitemouth croaker Micropogonias furnieri from five localities along the Brazilian coast revealed 8735 parasites belonging to 41 metazoan species. Samples from Ceará to Bahia and Rio de Janeiro to Santa Catarina showed a high level of correct assignation (92 and 87%, respectively) and cross assignation (i.e. almost all specimens misidentified in Ceará were assigned to Bahia and almost all specimens misidentified in Bahia were classified as Ceará), so samples were pooled in the northern and south-eastern samples, and Rio Grande do Sul was considered a southern area. Eight parasite species were characteristic of the northern localities, five species were found just in the area associated with south-eastern localities and two species were characteristic of the southern area providing first evidence of stock discreteness. The multivariate discriminant analysis successfully discriminated three groups of localities associated with three stocks of M. furnieri in Brazil: a northern stock associated with Ceará and Bahia, a south-eastern stock related to Rio de Janeiro and Santa Catarina and a southern stock in the area of Rio Grande do Sul, which could be considered as the northern limit of the stock associated with the Common Fishing Zone of Uruguay and Argentina.