Varia??o espacial e temporal de bagres marinhos (Siluriformes, Ariidae) na Baía de Sepetiba, Rio de Janeiro

摘要

Marine catfishes (Ariidae) are abundant fishery resource in the Sepetiba Bay, Rio de Janeiro State (Lat. 22o54?-23o04?S; Long. 43o34?-44o10?W), that is considered an important rearing area to a great number of juvenile fish. Artisanal fisheries are important economic activity in the region. Spatial and seasonal distribution and relative abundance of marine catfish, based on the number and weight of fish catched per sample (Catch per Unit Effort = CPUE) were assessed based on 151 otter trawl sampling in seven sampling sites in the Sepetiba Bay, between July 1993 and June 1996. For spatial comparisons, the study area was devised in an inner zone, located in the inner Bay and an outer zone, near to the sea limit. Environmental parameters of surface and bottom water temperature and salinity, transparency and depth were recorded at each sampling. A spatial variation pattern, assessed by multivariate methods, is shown with higher depths and transparencies in the outer bay and lower in the inner bay, while salinity seems to decrease slightly toward the inner bay. Only temperature showed seasonal variation. Five marine catfish species were recorded in the following order of decreasing numerical abundance: Genidens genidens (Valenciennes, 1839), Cathorops spixii (Agassiz, 1829) Sciadeichthys luniscutis (Valenciennes, 1840), Netuma barba (Lacepéde, 1803) and Bagre marinus (Mitchill, 1814).The top four abundant marine catfish occur in higher abundance in the inner Bay, with indication of spatial separation within this area. G. genidens was abundant over all sampling sites in the inner Bay, while C. spixii showed a narrower distribution in this area. N. barba concentrated near to Guandú River estuary, and S. luniscutis showed an ample distribution over all the Bay. Seasonally was not marked for all species. Strategies of spatial separation may be explaining the coexistence of marine catfish in high abundance in the Sepetiba Bay, which is used as fish rearing area mainly due the low depths and transparencies, favorable conditions to their early life cycle development.