| Resumo: |
In the Argentine Sea (SW Atlantic), particularly in the Bonaerense Coastal Zone there are two frontal zones, the waterfront area of the Rio de la Plata and the southern area of the province called El Rincón. The fauna of the Bonaerense Coastal Area has its own characteristics and in the case of fish is defined by dominant species, as is the whole of Sciaenidae family composed of seven species: white mouth croaker (Micropogonias furnieri), striped weakfish (Cynoscion guatucupa), king weakfish (Macrodon ancylodon), black drum (Pogonias cromis), Argentine croaker (Umbrina canosai), drum (Paralonchurus brasiliensis) and southern kingfish (Menticirrhus americanus). In the present work is discussed in a comparative way various aspects of the reproductive cycle and also what are the mechanisms that determine the adoption of different reproduction forms of these species. The research covers the description of the reproductive process from the point of view of differentiation and its relationship with environmental variables and estimates of reproductive parameters such as size at first maturity, fecundity and spawning frequency. In the Buenos Aires coastal area it was observed that sciaenids adopt different reproductive tactics depending on environmental characteristics of spawning areas. It is possible to group the species into three groups: Estuarine spawner associated with the bottom salinity front, are the species that spawn mainly in the inner area of the estuary in line with the bottom salinity front (iM. furnieri, P. cromis/i and iM. ancylodon/i); Estuarine spawner not associated with the bottom salinity front, the spawning of these species are mainly located in the middle of the estuary in brackish waters with salinities ranging between 25 and 30 psu (Paralonchurus brasiliensis and iM. americanus/i); Marine spawner, the spawning are located always in salt water (values above 30 psu) in outer zone of the Río de la Plata estuary and El Rincón (C. guatucupa, U. canosai and M.furnieri in the area of El Rincón).
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