Opsanus beta: AN INVASIVE FISH SPECIES IN THE SANTOS ESTUARY, BRAZIL

A non-indigenous fish species, Opsanus beta, was found during an ichthyofauna sampling program in Santos Estuary. Common on the west coast of Florida and the Caribbean, the most probable source of this occurrence is due to water ballast from the ships. The 140 specimens reported (18 to 323 mm TL; 8 to 442 g WT) were caught in fish baited traps (215.28 +/- 5.95 mm TL; 207.36 +/- 16.42 g WT; 25.7% of the total caught), otter-trawls (213.97 +/- 5.87 mm TL and 194.92 +/- 11.31 g; 54.3%) and gillnets (226.93 +/- 5.40 mm TL and 218.14 +/- 17.01 g; 20.0%). Of 81 specimens sexed, 43.6% of females (n = 55) and 92.0% of males (n = 24) have mature gonads. Santos estuarine areas are very similar to the O. beta original environment, and allied to the absence of natural predators, and its environmental plasticity, projecting it as a well adapted species in region, which must be viewed as a potential serious implication to other Brazilian estuarine systems.