Morphometric variation in pink shrimp populations at Rio de Janeiro coast (SE Brazil): are they really similar in closer areas?

Farfantepenaeus brasiliensis and F. paulensis are the most exploited shrimps of SE-S Brazilian coast. Our aim was to verify if adjacent nursery areas with different environmental condition (Sepetiba and Guanabara bays, SE Brazil) influence on shrimp populations (eg, CPUE) and body shapes. Samplings were carried out during 12 months in those bays ca. 85 Km far from each other. Carapace length (CL), total body length (TL), wet weight, abdomen size and TL/CL ratio were used to analyze variations in shape through regressions. In general, F. brasiliensis was 4 to 6 times more abundant than F. paulensis. The sex ratio differed from 1:1 in F. brasiliensis in both bays, with dominance of females, largest catches occur in autumn. However, differences in size and morphology were found between bays, mainly regarding the TL/CL ratio. Shrimps in Sepetiba Bay have higher TL/CL showing a more "elongated shape" (larger abdomen) when compared to those from Guanabara Bay. Results suggest the existence of an estuary vs shrimp morphology relationship which results in differences in body shape even in spatially close areas. TL/CL ratio has proven useful for assessing shrimp populations differences and might be tested for tracking the origin of adult shrimps stocks at the coast.