Parasites of Argentine hake in the Argentine Sea: population and infracommunity structure as evidence for host stock discrimination
The use of parasites as biological tags allowed the identification of three stocks of Argentine hake Merluccius hubbsi in the south‐west Atlantic. A total of 344 fish caught in the Argentine‐Uruguayan Common Fishing Zone, San Matías Gulf, San Jorge Gulf and Patagonian Shelf, were examined for parasites and 26 species were found. Univariate analysis on both parasite populations and infracommunity descriptors, as well as a discriminant analysis, allowed the identification of three separate stocks, one composed of hake from the Argentine‐Uruguayan Common Fishing Zone, a second by fish from San Matías Gulf and a third comprising samples from both San Jorge Gulf and the Patagonian Shelf. Northern samples were characterized by low values of prevalence for most parasite species, with the exception of Corynosoma australe and Grillotia sp. 1. Among Patagonian hake, Anisakis simplex showed similar values of prevalence in all zones, fish from San Matías Gulf were characterized by Kudoa rosenbuschi, Grillotia sp. 1 and Contracaecum sp. Among all compared areas, San Jorge Gulf and the Patagonian Shelf were the most similar, sharing most of their biological indicators (Grillotia sp. 2, Pseudophyllidea sp. 1 plerocerci and Hysterothylacium aduncum); therefore, the hypothesis on the presence of a separate stock in San Jorge Gulf could not be confirmed. Varying environmental conditions and their influence on the distribution of both zooplankton and other hosts involved in the life‐cycles of parasites could be determinant factors for the differences observed among hake stocks.
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