Time-space distribution of Micropogonias furnieri(Perciformes, Sciaenidae) in a tropical estuary in Southeastern Brazil

Abstract

The whitemouth croaker, Micropogonias furnieri, is a commercially very important marine fish along its occurrence area that uses estuaries early in its life. In order to describe the time-space distribution of M. furnieri in Guanabara Bay, southeastern Brazil, bottom otter trawlings were carried out every fifteen days between July 2005 and June 2007. The monthly variation of the relative abundance of M. furnieri was checked from catch per unit of effort (CPUE), and the size structure of the caught species, in time and space, was analyzed from histograms with length (TL) classes with an interval of 0.5 cm. The Kruskal-Wallis test was employed to test the hypothesis that sampling sites were occupied by groups of equal mean of TL. The whitemouth croaker was present in all sampling sites throughout the year and juveniles were the most abundant population stratum. Statistically significant differences (p<0.05) in length classes between different sampling sites were found. While smaller individuals had a higher frequency in the upper and middle estuary, and some sampling sites at the lower estuary, larger individuals were found mainly in the lower estuary. Recruitment peaks occurred in late Fall, Winter and Spring, indicating a long period of reproduction. Guanabara Bay has an important role as marine nursery and growth area for M. furnieri, with the physiography of the estuary being one of the most relevant factors in the space distribution of the species.