Feeding ecology of Urophycis brasiliensis on the Uruguayan coast of the Río de la Plata estuary
2007
Acuña Plavan, A. | Sellanes, J. | Rodriguez, L. (Luis) | Burone, L.
The Brazilian codling (Urophycis brasiliensis) is the target of an important artisanal fishery in Uruguay. In the present study we analysed the feeding habits of this species over a 2-year cycle. The samples were obtained from landings of the artisanal fishery at two sites on the Uruguayan coast: one representing a transitional habitat between estuarine and marine conditions (Piriápolis), the other representing a typical marine ecosystem (La Paloma). Different approaches were considered (Index of Relative Importance, IRI; graphical methods and multivariate techniques of cluster analysis and Principal Component Analysis). The ontogenetic changes in the diet were also assessed. Stomach contents of 870 individuals were analysed and a total of 24 prey species identified. The shirmp Artemesia longinaris has the highest IRI (89.9%) score followed by Cynoscion guatucupa (IRI = 4.3%). Molluscs were only marginally represented (IRI < 0.01%). Both the graphical method of Cortés and the method of Amundsen indicate the specialization of Brazilian codling to A. longinaris. However, a trend to a generalist diet evolves in bigger fishes, which also consume fishes in important quantities, mainly C. guatucupa. Moreover, opportunism is occasionally present both seasonally and spatially, and responds to variations of the availability of prey items throughout its distribution. U. brasiliensis predation plays an important role in the trophic dynamics of the SW Atlantic ecosystem. It is dependent on shrimp for feeding, a reason for an integrated management of coastal habitat and fisheries of both resources. The dependence of Brazilian codling, mainly when it is small, on shrimp calls for an integrated management of both the coastal habitat and fisheries.
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