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Variations in the measures of argentine hake (Merlucius hubbsi) rings otoliths during their first-year: evidence for stocks separation?
G.J. Torres, W. Norbis and M.I. Lorenzo

Measures of pelagic, demersal and first-year rings of otoliths belonging to two length groups of Argentine hake (Merluccius hubbsi) from the oceanic front of the de la Plata River (Argentine - Uruguayan Common Fishing Zone - AUCFZ) were analyzed. One group (individuals smaller than 25 cm) belonged to the nursery area of the northern sector (34º30’-36º00’S). The other group (individuals larger than 40 cm) belonged to the population that can migrate (northward and southward of the AUCFZ) and therefore could be found in most of the species distribution area. The variables which corresponded to the first length group (individuals smaller than 25 cm) presented higher mean values and less dispersion for each otolith ring measured (pelagic, demersal and first-year) than the second length group (individuals larger than 40 cm). These differences are significant (p<0.05). Linear and quadratic discriminant functions were also significant (p<0.05). Several differences between the stocks support the hypothesis of stocks separation between different zones within the species distribution area. These differences include: otoliths rings measurements; different latitudinal temperature; different spawing periods, different spawning areas and the different lenght of maturity start.

Keywords: Argentine hake, Merluccius hubbsi, otoliths, stocks separation.
Contents of this volume Sci. Mar. 60(2-3) : 331-338 Back PDF
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