Length-weight relationship and condition factor of Micropogonias furnieri (Desmarest) (Perciformes, Sciaenidae) in the Sepetiba Bay, Rio de Janeiro State, Brazil

The length-weight relationship and spatial, temporal and ontogenetic changes in the condition factor of Micropogonias furnieri (Desmarest, 1823) were analyzed, from samples collected between October 1998 and September 1999, in the Sepetiba Bay, a coastal area with a wide communication with the sea (22º54'-23º04'S, 43º34'-44º10'W) at Southeast Brazil. The aim was to supply basic information on the form of growth of the population of M. furnieri that uses the bay, as well as to assess changes in the fish condition. Most fish were young and subadults. The length-weight equation, based on 2499 unsexed individuals, was Wt = 0.009095 * Lt2.99, where Wt is the total weight (g) and Lt is the total length (cm). The regression constant and the regression coefficient presented significant inverse relationship (p < 0.01), indicating that the regression coefficient from the length-weight relationship is not a good parameter for characterizing different populations, because its strong association between one another. The best condition was recorded in October/November and April, and the worst, between January and March. Spatially, the best condition was observed in the inner bay zone, where most fish were young-of-the-year, and in the outer zone where predominate larger sized fish, indicating that individuals of intermediary size could be allocating large amount of energy for growth, presenting, consequently, lowest condition. Isometry was detected for M. furnieri populations at Sepetiba Bay, and variations in physiologic condition could be associated to feeding availability, mainly in the inner zone, where the harsh water quality would not be constrained for development of this species.