Parasites of Argentine hake in the Argentine Sea: population and infracommunity structure as evidence for host stock discrimination

Abstract

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.

Kudoa alliaria in flesh of Argentinian hoki Macruronus magellanicus (Gadiformes; Merlucciidae)

“…different sequences may represent multiple alleles of the same gene). It is important to identify genetically distinct parasite populations and species, especially where parasites are used for identification of fish stocks (Sardella & Timi 2004). Severity of infection, susceptibility of hosts, and distribution may vary between species.…”

Solapamiento trofico entre el lobo marino de un pelo Otaria flavescens y la pesqueria de arrastre demersal del golfo San Matias, Patagonia, Argentina

“…Desde hace más de tres décadas se desarrolla una pesquería dirigida al complejo de especies demersales y demersal-pelágicas. De acuerdo a sus propiedades oceanográficas y biológicas, se ha sugerido que algunas de las especies forman unidades demográficas diferentes a las existentes en la Plataforma Continental Argentina, como es el caso de la merluza común Merluccius hubbsi, principal especie blanco de la pesquería (Di Giácomo et al, 1993;Sardella & Timi, 2004;González et al, 2007). Esta condición de sistema semi-cerrado del golfo San Matías podría generar escenarios particulares para la interacción entre la flota pesquera de arrastre demersal que opera en el golfo y algunos predadores tope del ecosistema.…”

The mesoparasitic copepod Trifur tortuosus Wilson, 1917 (Pennellidae): Redescription with notes on its congeners

“…Additional specimens from previous studies on Argentine hake, M. hubbsi (cf. Sardella and Timi 2004), Brazilian sandperch, P. brasilianus (cf. Timi et al 2008) were also studied.…”