Systematics, distribution and ecology of commercially important paralichthyid flounders occurring in Argentinean-Uruguayan waters (Paralichthys, Paralichthyidae): an overview

Species of Paralichthys Girard are the most important flatfishes to commercial fisheries in nearshore waters of Argentina and Uruguay. Recent commercial catches increased from 3000 tonnes (t) in 1984 to 11000 t in 1995, representing more than $65 million in export income for 1995. Although their commercial importance has long been recognized, paralichthyid flounders in this region are not well studied, either from a systematic or an ecological viewpoint. Six nominal species have been reported from Argentinean and Uruguayan waters: Paralichthys bicyclophorus, P. brasiliensis, P. isosceles, P. orbignyanus, P. patagonicus and P. simulans. However, species descriptions are often vague and incomplete, and reported distributions are dubious. Variations in scale morphology, meristic and morphometric characters were used to differentiate among the Paralichthys species co-occurring in this area. Of six species previously reported from this region, only three, P. isosceles, P. orbignyanus and P. patagonicus, are valid. P. bicyclophorus is regarded as a junior synonym of P. patagonicus; P. simulans is a junior synonym of P. orbignyanus; while P. brasiliensis, although reported from coastal waters of Argentina and Uruguay for many years, does not occur there. Paralichthys spp. were collected on the continental shelf and in estuaries in the south Atlantic between 34–55°S. P. orbignyanus and P. patagonicus inhabit marine and estuarine locations and extend as far south as 43°S. The former is a shallow-water, euryhaline species occurring to about 20 m. In contrast, P. patagonicus has higher densities between 36–40°S at 70–100 m depth. P. isosceles occurs mainly on the inner continental shelf between 43–45°S at 70–100 m depth, and reaches its southern limit at about 47°S.